Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: txtune on September 25, 2020, 01:35:58 pm
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I have a ASR-120 model tube amp that I am considering restoring. I have found schematics and rebuild kits online, with the exceptions of the transformers. Maybe the transformers are still good, but they look kind of rough.
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Post schematic
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Post schematic
See attached.
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Maybe the transformers are still good, but they look kind of rough.
Those transformers look fine to me. They could use a little polishing up, but I bet they are all fine.
The output tubes are very similar to 6V6s so output transformers would be the same. You have voltages given for the power transformer, so if you need a replacement, just get one that will fit the footprint and provide the same voltages.
I would not even consider new transformers before doing a power on evaluation. Once more, I bet they are all fine.
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The output tubes are very similar to 6V6s so output transformers would be the same. You have voltages given for the power transformer, so if you need a replacement, just get one that will fit the footprint and provide the same voltages.
I would not even consider new transformers before doing a power on evaluation. Once more, I bet they are all fine.
Would you kindly point me in the right direction on how to evaluate these transformers? Thank you.
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I'd pull the PA tubes, OHM from tube socket pin 3 to "other" tube socket pin 3, should be ~~220ohms (no speakers)
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I'd pull the PA tubes, OHM from tube socket pin 3 to "other" tube socket pin 3, should be ~~220ohms (no speakers)
And then pull the rectifier tube and measure the AC voltage on all secondary windings.
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> schematic
Cropped:
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Thank, thank you
:thumbsup:
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Agree there is no reason to fret about the OTs. Yet.
It is not mil-spec, sure to last 50 years in a sandstorm in the arctic. Early 1950s S-Cs used enclosed OTs but clearly the Stereo Craze forced them down-market to "kitchen radio transformers" (larger, but still semi-open construction). I have cheap iron that old and older in my Kent and Philco, and they play fine today.
*ME*, I would take it out on the driveway with a long cord, hide my eyes, plug it right in. People will say "that's dangerous and bad for the gear!!" Well, gee, buy new gear if you don't like blowing-up and fixing stuff.
(https://memegenerator.net/img/instances/76524898/if-we-could-blow-up-more-stuff-we-could-put-everyone-back-to-work-fixing-it.jpg)
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I'd pull the PA tubes, OHM from tube socket pin 3 to "other" tube socket pin 3, should be ~~220ohms (no speakers)
Just to clarify, you would pull the 7408 tubes and OHM between pin 3 on two of the 7408 tube sockets at a time? This is done with no power to the unit right? I feel like I am about to get tomatoes thrown at me. :icon_biggrin:
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*ME*, I would take it out on the driveway with a long cord, hide my eyes, plug it right in. People will say "that's dangerous and bad for the gear!!" Well, gee, buy new gear if you don't like blowing-up and fixing stuff.
(https://memegenerator.net/img/instances/76524898/if-we-could-blow-up-more-stuff-we-could-put-everyone-back-to-work-fixing-it.jpg)
That is kind of my style, what would you do next... if nothing catches fire? What about if something does catch fire? Would you then replace only the burnt portion and start from the top?
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YES, No power, and yes, do it twice. Then as Sluckey said, pull Rec tube, THEN power up n check Power supply secondary voltage AC
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YES, No power, and yes, do it twice. Then as Sluckey said, pull Rec tube, THEN power up n check Power supply secondary voltage AC
Ok. Should the two 7408 on the L side and R side should have ~220ohms between them on pin 3?
Is there any reason I could not pull all tubes first? Check the L and R 7408 sockets, between pins 3 on each socket, then power up and check the supply secondary voltage AC?
I am going to do this at my shop on Monday where, at the very least, somebody can call 911 if I get lit up... though I will use appropriate PPE.
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not sure the confusion, there are 4 tubes and 2 OT, left side has 2 tube 1 OT, same for Right. so pull ALL 4 PLUS rectifier tube, make 2 measurements 1 for L side, pin 3 to pin 3. 1 for R side, pin3 to pin3. NO power just ohms
THEN apply power and measure Volts AC on the secondary side of Power transformer
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not sure the confusion, there are 4 tubes and 2 OT, left side has 2 tube 1 OT, same for Right. so pull ALL 4 PLUS rectifier tube, make 2 measurements 1 for L side, pin 3 to pin 3. 1 for R side, pin3 to pin3. NO power just ohms
THEN apply power and measure Volts AC on the secondary side of Power transformer
That is what I was proposing in my last thread. Of the total 7 tubes on the unit I do not know which one is the rectifier tube though. Is it the tube next to the power transformer?
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look at the documentation you provided, it spells out all the tubes, V13 is the rectifier
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Thanks shooter you have been super helpful!
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I'd pull the PA tubes, OHM from tube socket pin 3 to "other" tube socket pin 3, should be ~~220ohms (no speakers)
And then pull the rectifier tube and measure the AC voltage on all secondary windings.
I just got around to this today, work has been busy. When I OHM from pin 3 to 3 I am getting 237 on one side and 240 on the other. I checked with two different multimeters, both of them gave the same reading. Would that be considered ok? Is the secondary side of the power transformer the black and red wires, in the schematic, that are shown connecting to the rectifier tube socket, labeled 320VAC?
Thanks
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237 on 1 side and 240 on the other side sounds pretty good to me. They're not always that close.
You will have 4 wires connected to the rectifier socket from the power transformer. 2 of them should be yellow for the 5 volt heater, although they're not always yellow. The other 2 are the secondary high voltage winding. There should be a ground wire from the power transformer to the chassis for the high voltage winding. If you check with the multimeter between the high voltage windings, you should get some amount of resistance. If you check from each of the high voltage wires to the chassis, you should get approximately half the resistance from each wire on the high voltage side to ground.
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237 on 1 side and 240 on the other side sounds pretty good to me. They're not always that close.
You will have 4 wires connected to the rectifier socket from the power transformer. 2 of them should be yellow for the 5 volt heater, although they're not always yellow. The other 2 are the secondary high voltage winding. There should be a ground wire from the power transformer to the chassis for the high voltage winding. If you check with the multimeter between the high voltage windings, you should get some amount of resistance. If you check from each of the high voltage wires to the chassis, you should get approximately half the resistance from each wire on the high voltage side to ground.
I get 130 between the two secondary side wires, and 67 and 62 between ground and each of the secondary wires. Should I now plug in and check for AC voltage? On those wires? If so, what should I expect to see? thx
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1st, what is the MAX AC volts your meter can read?
I would measure each leg to ground 1st
so gator clip the black lead to chassis
gator clip red lead to either red wire
power up, get reading
power down, discharge caps
repeat for 2nd red wire
post volts
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EIA 352 is Magnetic Windings Co., Easton, PA
maybe a stereo low-power (30W) SUNN type amp with a split chassis for preamp? you could rewire for use with 6AN8 or 6U8, as as those are lower cost and easier to source than 7199.
for monurol use, strap OT's in series and you should be able to drive a 4Ω to 8Ω load, or strap a 8Ω speaker and a 16Ω speaker in parallel for 5.33Ω
--pete
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1st, what is the MAX AC volts your meter can read?
I would measure each leg to ground 1st
so gator clip the black lead to chassis
gator clip red lead to either red wire
power up, get reading
power down, discharge caps
repeat for 2nd red wire
post volts
Max voltage on the meter is 1000
It did not show any voltage on either of the red leads going to the rectifier tube socket.
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my bad, missed this, that DL alluded to
either cut the 2 wires that go to 6 and 9 EDIT: and twist n solder, or solder a jumper across 6-9
then measure volts AC red to red since your meter can handle it
If it seems good ( maybe 400-600vac)
being careful measure green to green (filament)
and Yellow to yellow
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Nothing on red to red after I soldered 6 and 9 together.
EDIT: You are talking about the red wires I have circled AND the 6 & 9 pins from the modular plug that I have circled, correct?
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yep;
verify the fuse is good
what's the black chunky thing on right - accessory plug?
i'm sketching up an eliminate rat's version
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here's a hot wire "fix" IF... the fuse is blown
IF the fuse is not blown;
measure VAC from each brown wire to chassis ground to verify there's stuff coming in
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yep;
verify the fuse is good
what's the black chunky thing on right - accessory plug?
i'm sketching up an eliminate rat's version
Glad to hear this, I really thought I had to be doing something wrong.
Black chunky thing is indeed an accessory plug for the radio or the turntable, cannot remember which.
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here's a hot wire "fix" IF... the fuse is blown
IF the fuse is not blown;
measure VAC from each brown wire to chassis ground to verify there's stuff coming in
Continuity was intermittent on the fuse, not sure I have seen that before. I plan to make some modifications to this device anyways, so I will go ahead and install the hotwire 'fix'. I cut the two wires you circled, then reconnect them based on your diagram, correct? Just checking that the brown and black in your diagram are the two that you circled. Thank you.
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yes the ones you cut, power wire (brown) feeds fuse, tranny wire (black) feeds the tranny
decide where you want your power switch, drill n mount it. decide where you want a fuse, drill and mount it.
hook up like diagram, use a 3 prong power cord, connect the green wire somewhere close to where it comes in. I typically drill a hole and bolt it down near the power in
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Could I use a pop out breaker like this (https://www.alliedelec.com/product/te-connectivity/w58-xb1a4a-2/70199386/) in place of the slow blow fuse?
Also, if I am replacing the power cord... where should I connect the incoming white/neutral wire? Should I cut the wires (circled in green) loose and tie the incoming white to the black?
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yes and yes
fuse/breaker the black, the white goes like you indicated
you "might" get nuisance trips from the breaker vs a slo-blo, so if you're planning on maskin up hitting the gig trail, fuse might be better, at home in boxers the breaker should be fine
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yes and yes
fuse/breaker the black, the white goes like you indicated
you "might" get nuisance trips from the breaker vs a slo-blo, so if you're planning on maskin up hitting the gig trail, fuse might be better, at home in boxers the breaker should be fine
The 'other' white wire, right above the green circle in my markup, can I cut that out completely? I may use that cutout in the frame for a power entry module.
Boxers and breakers it is. :laugh:
I went ahead and bought this (https://www.ebay.com/itm/Stromberg-Carlson-ASR-120-ASR220-restoration-kit-service-recap-capacitor-rebuild/164155403954?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) restoration kit on fleabay... perhaps from someone on this forum.
My overall plan is to be able to input a radio or TT (via RCA) and output to some bookshelf speakers. I have zero idea how to get there, but I am going to give it my best. :help:
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I colored out all the wires you can delete.
strip down the terminal strip AFTER you have enough original pic's to be happy
NOTE ANY wire that comes from the tube OR the PT (power transformer)
once it's all shiney clean, draw up "your vision" for best use of the nice clean ready to use terminal strip
draw it schematically 1st, then layout 2nd, you'll be listenin to bookshelf music soon
I'll do some sketchin, but I didn't retain any early stuff so I gotta go back for 2nd's
edit: attachment :BangHead:
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Wow, thanks shooter! :worthy1:
I will take many photos before, during, and after. Would you recommend I first install the 'hotwire' and get a reading from the secondary side of the PT? Or should I just start removing wires and get it down to bare bones, then start building back from there?
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depends;
if it smokes are you gonna stay with it and throw parts at it til music comes out?
If so, i'd get the 1st load of junk out, "start the process"
If NOT, hot-wire with duck-tape n gatorclips, make sparks :icon_biggrin:
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depends;
if it smokes are you gonna stay with it and throw parts at it til music comes out?
If so, i'd get the 1st load of junk out, "start the process"
If NOT, hot-wire with duck-tape n gatorclips, make sparks :icon_biggrin:
Ok, so I wanted to try it out first to make sure I got voltage off the secondary side of the PT. It occured to me that the old style power cord on this unit could be plugged in either way... meaning I could remove the plug from the wall and turn it 180 degrees and plug it back in. The way I was plugging it in caused the brown wire, circled in red, to be the incoming 120VAC. So I put the hotwire, breaker, and switch, in right there. Then I tied the other brown and black together and turned it on, which resulted in 716VAC on the two red wires connected to the RT socket. Now then, when I go to hook it up in the permanent configuration... does it matter which of those black wires I use for the neutral and which I use for the incoming hot wire from the wall?
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Nope, but I believe there is a CT red/yel, where THAT wire goes is important, should be connected to ground.
so do you get ~ 6.3vac across the filaments (green-green)? does the lamp light?
are the tubes still in? IF so do the filaments glow in all 5(?) tubes?
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Nope, but I believe there is a CT red/yel, where THAT wire goes is important, should be connected to ground.
so do you get ~ 6.3vac across the filaments (green-green)? does the lamp light?
are the tubes still in? IF so do the filaments glow in all 5(?) tubes?
CT = Center tap? I see the red/yellow wire you talking about. It goes to the bottom of the round metal housing near the RT. Orange arrow pointing to it.
I will go test the across the green wires.
I have the tubes, I will try them and see what happens.
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so do you get ~ 6.3vac across the filaments (green-green)?
I was getting right around 7vac
does the lamp light?
The small lamp does not light.
are the tubes still in? IF so do the filaments glow in all 5(?) tubes?
I put the RT and the four large tubes back in and all of them lit up!
What's next? The smaller transformers and tube sockets?
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nope
staying with power
take all tubes out except the rectifier, put that in
look at the schematic, to the right of the rec tube "looks" like C52?
put the red lead on the + side of cap, the black lead on chassis ground
power up and measure Volts DC! leave it on maybe 3-5 minutes watching the meter like a mother hen, keep your nose n eyes working for ANY sign of "she's gonna blow"
If you make it that far, we might have music soon, so hunt down your favorite junk speakers
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Would you be so kind as to point out the + side of the cap in one of these pictures?
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> does it matter which of those black wires I use for the neutral and which I use for the incoming hot wire from the wall?
No. Not a bit. If it does, you have a bad connection "sometimes".
Since you have seen 700VAC come out, I strongly suggest you find a FRESH gig-worthy power cord with a ground pin/wire and do-up the 120VAC wiring properly.
> point out the + side of the cap
99.44% of the time, the "can" of a can-cap is negative, the lugs in the middle are positives.
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Use your schematic to "follow" along;
start at the rec tube, find the pin that "feeds" the DC "power rail" (the "line" with voltages going "up")
you can measure (ohm NO power)the resistors as you go and verify with schematic, anything within 25% is good for now :)
once you're happy you have the correct point, THEN you can switch to VDC connect meter and watch, closely
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Since you have seen 700VAC come out, I strongly suggest you find a FRESH gig-worthy power cord with a ground pin/wire and do-up the 120VAC wiring properly.
Yes, I agree.
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Use your schematic to "follow" along;
start at the rec tube, find the pin that "feeds" the DC "power rail" (the "line" with voltages going "up")
you can measure (ohm NO power)the resistors as you go and verify with schematic, anything within 25% is good for now :)
once you're happy you have the correct point, THEN you can switch to VDC connect meter and watch, closely
I took these photos yesterday before I read your latest post, which I am quoting here. The vdc leveled out at 450 on the pin, pictured below, that I chose at random.
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monitor it for the 3-5 minutes, look for sudden drops or surges, slow bleeds. If it stays basically "centered" then you're good for now.
look at the schematic, upper right in blue
NO POWER, ohm that resistor to make sure it's close to stated value.
IF close, black lead to chassis, red lead probes each of the 4 socket's (tube side), each tube should ohm ~ the same as the resistor. look at the schematic, trace that circuit so you get the correct tube pin to ohm.
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monitor it for the 3-5 minutes, look for sudden drops or surges, slow bleeds. If it stays basically "centered" then you're good for now.
look at the schematic, upper right in blue
NO POWER, ohm that resistor to make sure it's close to stated value.
IF close, black lead to chassis, red lead probes each of the 4 socket's (tube side), each tube should ohm ~ the same as the resistor. look at the schematic, trace that circuit so you get the correct tube pin to ohm.
The one I circled in orange? I got 150 on it.
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assuming that's the correct 150ohm;
look at the schematic;
one side of the 150 should go to ground
the other side should go to all 4 PA tube's cathodes
Verify by following wires, use meter to ohm ALL 4 PA tube cathode pins to ground (ohm at tube side of socket)
once that's done find yourself a stereo jack 3mm 1/8", 1/4",RCA, whatever you want to use to plug your music source into. also scrounge up 2 caps, .1 - .01uf.
did your voltage stay about constant during the 5 minute test?
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did your voltage stay about constant during the 5 minute test?
The voltage stayed constant at around 450vdc for five minutes.
I will check this more thoroughly tomorrow, it's been a busy week. Thanks for your patience!
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:m17
I spent 10yrs with '90's teens, patience is a must :icon_biggrin:
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:m17
I spent 10yrs with '90's teens, patience is a must :icon_biggrin:
Hey, I was a '90's' teen ... this should be a walk in the park for you! :laugh:
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:laugh:
I can spot 'em a mile away, NOW, you do your part and you're shakin window's :icon_biggrin:
think about "the look", it will be a big part of the stereo. Once it's playing some good grunge, although Nelli (sp?) is playin in my head currently
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:laugh:
I can spot 'em a mile away, NOW, you do your part and you're shakin window's :icon_biggrin:
think about "the look", it will be a big part of the stereo. Once it's playing some good grunge, although Nelli (sp?) is playin in my head currently
I am probably going to have to learn how to solder as well. :dontknow:
As soon as I hear some music come out, I will probably go ahead and strip it down to refinish the frame. Should I be looking for any hard to get parts? Tubes, sockets, etc?
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let's get music or noise 1st.
If you don't have a good soldering equipment, start there. hunt up some junk pcbs, old junk chassis, things that can be burnt up as you learn NOT to burn up. maybe hunt up an 'ol guy that's in your area that can solder, buy him a 6 pack, or a 1/4 oz, learn 1st hand :icon_biggrin:
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let's get music or noise 1st.
If you don't have a good soldering equipment, start there. hunt up some junk pcbs, old junk chassis, things that can be burnt up as you learn NOT to burn up. maybe hunt up an 'ol guy that's in your area that can solder, buy him a 6 pack, or a 1/4 oz, learn 1st hand :icon_biggrin:
lol ... I think I have some ideas. I know some older traffic signal techs.
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Ok. I circled the wrong cap item last time. Take a look at these images, same image actually... one is marked up the other is not. I got ~150 on the device I circled. Then I marked the wires that I OHM'd, chassis ground to pin on socket, and I got 157 or 158 on all four of them.
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:thumbsup:
Since you are new at this, I would highly recommend getting the input power "set", holes drilled, chassis cut, stuff. High voltage is nothing to "play" with. wires, switches, fuses, all dangling is a recipe for disastrous outcomes.
buy, find, or re-purpose an EIA connector, mount it where the original 2 pronger is. I'm calling that the "back" of the chassis. Doug has both eia and power cords at his store
https://hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=FusesCords&ORDER_ID=743790629 (https://hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=FusesCords&ORDER_ID=743790629)
I would mount my power switch and breaker there also. pita having to reach in back to power on/off but taking it to the front gets way to close to the preamp IMO.
maybe others have a better option, maybe you do. The point is, make it safe to continue.
a power on light is also REAL handy, yours indicates one but my guess is was mounted on the "other chassis"
Doug also has something that will work off the filaments just like your schematic indicates
https://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&template&thispage=Lamps&ORDER_ID=!ORDERID! (https://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&template&thispage=Lamps&ORDER_ID=!ORDERID!)
the fender 6.3 volt, socket, and bezel. figure out where you want that mounted.
those parts will give you a good start on soldering, so find someone, make a day of it.
remember the turtle always wins.
take the schematic, some blank paper, your favorite crayon, and draw up all the connections and parts i've listed above, how "you're" gonna connect them to the original
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Ok. I suppose it's time to take this down to bare metal and clean it anyhow. I have taken quite a few photos from nearly every angle, I am sure I missed something.
If I do want to connect the stereo input (RCA jacks) and output (speaker wire connections) ... where do those connect?
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If you haven't already started;
re-working the power to be safe can all be done on the "back", no need to strip it all down yet to get music.
I would mount the RCA jacks in "front", there a 2 small tubes, your driver tubes, the RCA's will connect to them, you want short wires 6" or less if possible. (see the orange square on attachment, that's IN) Also note I put 2 .1uf caps "in-line" They may not be needed, but if you plug something In that has DC volts on it, you will be happy they're there
the speaker out's come off the 2 identical looking transformers, the problem there, your AC In will take up some of the "back", you want the speaker wire away from the AC IN, can still be on the back, you just have to think things through so you have a clean layout instead of a spaghetti bowl of wires.
When you DO tear it down, DOCUMENT, and learn the "terms" (your original documents have something like C42 in a circle pointing to a component. It also has a parts list that references "C42" and gives a discription)
study those sheets til you see circles when you close your eyes, you've quit eating, can't sleep because you're so focused on learning this amp :icon_biggrin:
example that 150 ohm resistor is the cathode resistor, your notes should say something like "yellow wire from cathode resistor" always specify where the wire went. leave all the wires on the board, disconnect at sockets, switches, etc, AND LABEL them.
since you're not soldering yet, clip the wires within a 1/4" of where they're soldered to. then your 1st soldering job will be to remove that 1/4" wire and clean up all the connections, sockets, etc.
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Thanks shooter. Let me chew on all of this and get back to you.
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to windy to fly so sketched up a cleaner schematic (CHECK for errors, edit in .sch :)
EDIT missed a resistor :BangHead:
AND bypass cap
_2 should be correct
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to windy to fly so sketched up a cleaner schematic (CHECK for errors, edit in .sch :)
EDIT missed a resistor :BangHead:
What type of aircraft? My Dad had a '66 V35 Bonanza, that was an awesome machine.
Do you use a specific software to create schematics?
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:laugh:
I'm learning to fly sUAV's, hoping to get my commercial licence in the spring, but studying maps and rules and and..... is NOT much fun.
some of us here use expessSCH, it's free, pretty intuitive, I've been using it since it came out in 3.5" floppies :icon_biggrin:
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:laugh:
I'm learning to fly sUAV's, hoping to get my commercial licence in the spring, but studying maps and rules and and..... is NOT much fun.
some of us here use expessSCH, it's free, pretty intuitive, I've been using it since it came out in 3.5" floppies :icon_biggrin:
Ah! I have a Phantom 3 Pro ... you are probably flying something much more complex. The technology is amazing in that arena.
I have another, multi-part, question for you. The schematic says to use Belden 8530 or 8524 wire.
1) Would you suggest stranded or solid?
2) Is the cloth insulation a thing of the past?
3) My local electronics dealer (Allied Electronics) only sells this wire in 100' reels. I would like to get several colors, but that will windup costing me a fortune. Any suggestions for a 'kit' of small reels, rated at 1000V? Or should I bit the bullet and get a couple colors from Allied?
Thanks!
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Click the link below this message for all the wire you need. Sold by the foot.
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Ah! I have a Phantom 3 Pro
:laugh:
not there, yet
I just have 2 Hubsan 501SS, FPV, way more fun breaking a $150 drone than a $2,000 one :icon_biggrin:
hopefully will be flying the P 4 pro + advantage(?) soon. having a fixed, low-quality camera is cheezy, except it really works well to get "the sense of flight" using FPV
OK, wire;
Sluckey pointed you to where
my personal preference is 22-24 GA Teflon stranded for everything but filaments, and inputs.
filaments I like solid core ~18 ga, in's I typically use RG174 but you gotta have GOOD solder chops so you don't melt the center coating into the shield
some use cloth wire, I've used it, I find it best to put shrink tube at both ends for an "aesthetic" look, but that's extra steps so I quit using it
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:laugh:
not there, yet
I just have 2 Hubsan 501SS, FPV, way more fun breaking a $150 drone than a $2,000 one :icon_biggrin:
hopefully will be flying the P 4 pro + advantage(?) soon. having a fixed, low-quality camera is cheezy, except it really works well to get "the sense of flight" using FPV
The phantom has been extremely 'forgiving'. I have crashed it twice at the deer lease, one was more of a crash landing... the other one was full on, full speed, drone-meets-tree. If there was a tiny crew on board, they would have walked away both times. I replaced the props and back up she went. I have video if you care to yell at your screen and laugh all at the same time. Perhaps I can send that through a PM.
I have not flown in awhile, I need to brush up on the current rules and regs.
OK, wire;
Sluckey pointed you to where
my personal preference is 22-24 GA Teflon stranded for everything but filaments, and inputs.
filaments I like solid core ~18 ga, in's I typically use RG174 but you gotta have GOOD solder chops so you don't melt the center coating into the shield
some use cloth wire, I've used it, I find it best to put shrink tube at both ends for an "aesthetic" look, but that's extra steps so I quit using it
I have zero solder chops. I bought a decent solder station yesterday, which made me feel like the person buying a good guitar with no idea how to play it. With that being said, can I use 22GA Teflon on everything?? Or should I use 18GA on the ins and filaments, just a different type?
I will give it the old college try before I pack it up and mail it to you. j/k I will order some wire now, the restoration kit won't be here until mid-week next week.
I added a PEM to the 'back' of the frame. I will put the breaker (for now) and the on/off switch in as soon as I get time. I bought some a couple of fuse holders with the same panel mount hole diameter as the breaker, so I can put a fuse in the finished product.
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:l2:
I have plenty of my own crash vid's!
re-read my post, tells what i use for filaments. inputs, if they are < 6" and not near any strong signals the small wire works fine.
find a broke boombox, start de-soldering stuff, then when it's clean and pretty, solder stuff back, couple hundred times should make you pretty good.
does your station do both suck solder and solder? If not you need a solder sucker, some solder wick. DO NOT start with eco-friendly lead-less solder, buy the good stuff. pick up some flux, look for the tube/syringe dispenser fine tip stuff.
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find a broke boombox, start de-soldering stuff, then when it's clean and pretty, solder stuff back, couple hundred times should make you pretty good.
does your station do both suck solder and solder? If not you need a solder sucker, some solder wick. DO NOT start with eco-friendly lead-less solder, buy the good stuff. pick up some flux, look for the tube/syringe dispenser fine tip stuff.
The solder station is a Weller Includes: WE1 with WEP70 and PH70.
I bought a separate desolder station on amazon, it has a built in vaccum. Should be here today or Monday.
I also ordered some Chemtronics 80-3-10.
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I have not given up on this, very busy lately. I hope to work get back to it soon.
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:laugh:
I haven't deleted the file i started either :icon_biggrin:
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I have the PEM, fuse holder, and on/off switch installed in the frame.
I started to de-solder the connections of wires that I removed already. The de-solder vacuum tool makes easy work of it, I assume much easier than soldering will be. I *think* I can handle soldering to the 'tabs' that have the holes in them. The ones that I removed solder from had the wires through the holes and bent back around the tab, then covered in solder.
With any luck I will be able to solder the PEM, fuse holder, power switch together and get it energized again so we can proceed to the next step.
Thanks again!
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the wires through the holes and bent back around the tab, then covered in solder.
You want a good mechanical bond before you solder, solder isn't a great conductor. Pay attention to those solder joints you're un-soldering, yours should be that good or better.
spent some time watching YT vid on "basic soldering"
no, i'm not gonna look for any :icon_biggrin:
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Here is my first attempt at soldering. I know it's not pretty, but will it work for now?
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More pics.
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not bad for 1st timer :icon_biggrin:
look at the white wire, you can see 2 "hairs" protruding, nbd there, but if it's a tube socket that "could" be enough to touch the next pin with 2 hairs.
the red wire on switch, looks pretty cold, almost like it's glued. flux will help, also, "pre tinning" the copper by applying solder just to the tab, then clean off excess, add wire and solder. when you see the solder start to flow, set off the 2 second timer in your head, so; flow, 1 thousand 1, 1 thousand 2, OFF with solder 1st then iron
you'll be ready for NASA soon :icon_biggrin:
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In a certain country you might be promoted to sweat shop supervisor by now with work like that :icon_biggrin:
Your doing a nice job on that relic. You know people pay extra for relic these days :l2: Don't polish it too much.
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Ok, I thought you guys/gals were going to give me a lot more crap than that! I will redo the switch solder, then try firing it up.
IF it does not catch fire when I turn it on, what is the next step?
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That green wire just may save your life one day... ***IF*** it has a proper secure connection to chassis. I would use a ring lug on the wire and bolt it to the chassis using a kep nut.
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good catch!
Once you fix the ground, I would suggest printing out the schematic I drew and "highlight" each wire you "changed", that should "lead" you to the rectifier tube AC side (NO power required :) AND it should make sense, if not ask.
You can figure out your RCA's, mount them and use the schematic to figure out what 2 wires will connect to them. also figure out where to mount a couple caps like I have in the schematic (they might be just for testing, or they may stay), also NO power required :icon_biggrin:
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That green wire just may save your life one day... ***IF*** it has a proper secure connection to chassis. I would use a ring lug on the wire and bolt it to the chassis using a kep nut.
Got it, I will do that tomorrow as well. Thanks!
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I repaired the ground issue per sluckey's advice, bolt and keps nut, fired it up and the fuse blew. Turns out I had the new power switch wired incorrectly... I had to get the fancy illuminated one... :smiley: I took the switch back out, removed the solder and wire, tested it, and soldered new wire leads on it.
Anyhow, since I am cleaning up my wiring a bit... would it be best practice to land the power supply AC neutral, switch lamp neutral, and power transformer neutral all in one place? That's how I had it and it was not pretty. Just wondering if I should land all three together on an empty terminal strip tab?
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I just connect everything to the switch. Nice and neat. Look at this pdf...
http://sluckeyamps.com/dual_lite/dual_lite.pdf
And here's an actual pic...
http://sluckeyamps.com/dual_lite/big_guts.jpg
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I just connect everything to the switch. Nice and neat. Look at this
Wow! That is slick. I really like the 'nice and neat' look. :worthy1: Have you been at this awhile?
I have a long ways to go, hopefully you kind folks have as much patience as I do determination.
There is a seller on ebay who auctions off one very nice amp every couple of weeks, mostly single ended 45 triode amps with Tamura transformers. One of you may very well know who that person is, or be that person. The overall 'simplicity' of his builds falls into the same category of nice and neat like your work.
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If you want to get good, study Sluckey's page, those are the "standards" you want to shoot for.
There's a member in your state that has produced some great "original works" schematics and amps.
so IF you put in the effort, you can't help but get better.
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Interesting. Do you know where in TX that member is located?
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good catch!
Once you fix the ground, I would suggest printing out the schematic I drew and "highlight" each wire you "changed", that should "lead" you to the rectifier tube AC side (NO power required :) AND it should make sense, if not ask.
You can figure out your RCA's, mount them and use the schematic to figure out what 2 wires will connect to them. also figure out where to mount a couple caps like I have in the schematic (they might be just for testing, or they may stay), also NO power required :icon_biggrin:
Unfortunately I am at a dead end. I am looking around for other folks who have restored this amp with a 'how to' guide. I will let you know how it goes.
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once you have a way to connect an audio source and speakers, the initial testing says it should play, then maybe figure out what it looks like :icon_biggrin:
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once you have a way to connect an audio source and speakers, the initial testing says it should play, then maybe figure out what it looks like :icon_biggrin:
I got the speaker terminals on, just used some cheap ones for now... I will use some good ones on the final. I planed to connect the RCA today, but realized I did not have all the proper caps and resistors... hence the earlier post. Fingers crossed I will get music to play out of this old amp tomorrow.
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once you have a way to connect an audio source and speakers, the initial testing says it should play, then maybe figure out what it looks like :icon_biggrin:
Finally got around to adding some inputs. As I mentioned in the 'cap' post, I found a blog online where someone (actually two people) were both rebuilding this exact model. The individual writing the blog took possession of the amp with some mods already done, though he plans to do much more. First two pictures are from blog.
I was running out of time this evening and finished up with a only a few minutes to connect it to some speakers. All I got was a constant hum, after the tubes warmed up, so clearly something ain't right. The speakers are tiny little samsung rear surround speakers from who knows where... I hated to plug this into anything nice... but I need to get something better than those. Could it be those speakers are not the right impedance for this amp? Or do you see something obviously wrong with my contraption? I forgot to get good pictures of the speaker hookup, but they are connected just as his are. I plan to use some better ones later, so I did not mount these.
EDIT: I see what I did, man it was a long day. :BangHead: What are those tabs on the RCA inputs actually for?
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I bet the one with the yellow caps does not work. :dontknow:
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:think1: :think1:
I started to delete my post, but decided to let it stand.
What are the little tabs on the RCA inputs actually for?
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They are ground tabs. Your yellow caps should be connected to the center pin on those phono jacks.
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Thanks Sluckey. I hope to get down there tomorrow and fix that. Did anything else jump out at you as 'danger' or 'won't work like that?'
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My only concern is that you are completely out of your element with this stuff. Just as I would be under the hood of my 2018 Highlander.
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My only concern is that you are completely out of your element with this stuff. Just as I would be under the hood of my 2018 Highlander.
I cannot argue with that assessment.
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Got the inputs connected to the center pins. I went ahead and connected some bookshelf size Klipsch speakers. Music came out!
The AM/FM tuner I am using for input only has line out volume control on the 3.5 headphone out. I found a 3.5 to dual rca and connected that in order to control volume. It is playing audio out of both left and right speakers, but there a loud humming noise coming from both speakers.
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That's progress. :thumbsup:
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That's progress. :thumbsup:
Thanks! It's not pretty.
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to windy to fly so sketched up a cleaner schematic (CHECK for errors, edit in .sch :)
EDIT missed a resistor :BangHead:
AND bypass cap
_2 should be correct
Shooter - Coming back around to this. While I still do not fully grasp all of the diagrammatic symbols, I am starting to make some basic sense of it. Starting with the cropped portion of your 'Stromboli' diagram, see attached
I am following power coming in from the wall plug, through the fuse and switch, then it goes through a transformer (I assume the power transformer) and I see the the resistors labeled R58 R459 (I think this is R59) R60 ... in between those resistors are lines with (I assume) voltage labeled 320 300 275 which run down to A B C caps labeled C62 (I think these are C52A B and C from the original schematic)
What happened to C52D? The 50u 25V cap in your schematic? Is it no longer necessary in the new configuration?
What would change for the new JJ cap that I am going to use?
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The JJ is a 40 20 20 20
so the 40 become "A", 20 becomes B, 20 becomes C
the "last" 20, i'd leave in case you get a little hum, that cap can be paralleled with A,B, or C to maybe knock down possible hum
Use your "kit's" caps for the PA cathodes, i didn't look at schematic, guessing 1 for each side, so use 2 equal value.
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Ok, I just poured over the photos I have taken and the schematics, side by side, focusing on the connections between the can cap, rectifier tube, power transformer, and all the resistors in that mix... it started making some sense.
When the JJ cap arrives I will keep you posted as it goes together.
Thanks again!
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See also Post #61 in the other thread:
"...if you decide to use the JJ cap, note that it has four capacitor sections: 40uf, 20uf, 20uf, and 20uf, all at 500v, right?
You need three high-voltage caps, with the original being specified as 40uf 450v, 30uf 350v, 15uf 350v.
There is also a 50uf 25v cap specified on the schematic and parts list - that could be replaced with the Nichicon 47uf 100v mentioned above (from your kit).
So my recommendation would be to use your new JJ cap in the following way to best meet the need: wire up two of the 20uf sections in parallel.
This will make your JJ cap have 40uf at 500v (to replace C52A, 40uf 450v on the schematic in the parts list), 20+20 = 40uf at 500v (to replace C52B, 30uf at 350v on the schematic in the parts list), and 20uf at 500v (to replace C52C, 15uf at 350v on the schematic in the parts list). This will meet or exceed all of the specs of the original power supply filter caps in the can. Finally, to replace C52D from the parts list, you can use that small Nichicon 47uf 100v, that came in your kit. That can be handled separately; we can come back to it later.
There are other ways to proceed, but this is my advice right now anyway."
Here is the same recommendation again, in list form:
C52A was originally in the parts list as 40uf 450v --> replace it with 40uf 500v in the JJ can
C52B was originally in the parts list as 30uf at 350v --> replace it with 20+20 wired parallel for 40uf at 500v in the JJ can
C52C was originally in the parts list as 15uf at 350v --> replace it with 20uf in the JJ can
C52D was originally in the parts list as 50uf at 50v --> replace it with that small Nichicon from your kit, 47uf at 100v
If you choose to follow this advice of wiring two of the 20uf can cap sections in parallel, let us know. We'll tell you how when it arrives and you tell us the letter codes on the terminals. It only requires a wire connection in the right place.
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We'll tell you how when it arrives and you tell us the letter codes on the terminals. It only requires a wire connection in the right place.
Thanks. I just checked the tracking and it still shows postage was printed on the 9th, but it's not in USPS system yet. It was late on Monday when I ordered, plus they were closed on Wed. I bet it gets here next Monday or Tuesday. I will keep this post going with updates when it arrives. Thx
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I did manage to get this old cap can apart and cleaned out, without destroying it completely.
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I enlarged the opening in the chassis where the old cap can was, the JJ is ready to go in. I hope to work on it tomorrow during the day... but that always depends on my regular work load (the kind that pays the bills).
Looking back over both suggestions, from Shooter and Joel, I have a few questions.
The JJ is a 40 20 20 20
so the 40 become "A", 20 becomes B, 20 becomes C
the "last" 20, i'd leave in case you get a little hum, that cap can be paralleled with A,B, or C to maybe knock down possible hum
This would give me the following, correct?
C52A - 40uf at 500v in the (JJ can)
C52B - 20uf at 500v in the (JJ can)
C52C - 20uf at 500v in the (JJ can)
C52D - Save in case needed
Can I parallel the "last" 20 with any of the taps? Or just with one of the other two 20s?
C52A was originally in the parts list as 40uf 450v --> replace it with 40uf 500v in the JJ can
C52B was originally in the parts list as 30uf at 350v --> replace it with 20+20 wired parallel for 40uf at 500v in the JJ can
C52C was originally in the parts list as 15uf at 350v --> replace it with 20uf in the JJ can
C52D was originally in the parts list as 50uf at 50v --> replace it with that small Nichicon from your kit, 47uf at 100v
Would this give me the following?
C52A - 40uf at 500v in the (JJ can)
C52B - 40uf at 500v in the (JJ can)
C52C - 20uf at 500v in the (JJ can)
C52D - 47uf at 100v (Nichicon)
Shooter and Joel, I really appreciate you guys helping out, and Sluckey too!
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Before I go any further I have a question about grounding this cap. The old can had tabs on it that were soldered to the chassis. This one is setup a little different. Should I run a wire between the chassis ground and the negative? Or from the chassis ground to an empty terminal strip tab, then connect the cap ground to that, as well as anything else that needs a ground connection?
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Connect the red/yellow wire from the PT to the cap can negative terminal. Also connect the negative terminal to chassis ground using a short wire with a ring lug. Secure the ring lug to chassis using one of the cap bracket screws.
It's OK to rotate the cap for a more convenient connection of the wires and components if needed. Looks like that big resistor was originally connected to one of the cap can mounting lugs, but it can connect to any chassis ground if more convenient. Or just connect it to the new can negative terminal along with the two wires installed above.
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Would this give me the following?
:thumbsup:
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Connect the...
How does this look before I solder it?
Also, the resistor you were talking about is the 150ohm 10W, correct? Would the new resistor (pictured below) be a suitable replacement?
Thanks
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Get rid of those loops on the green wire. Probably only needs to be about 1" to 1.5" long. Also use a kep nut or at least a star lock washer. That green wire needs a really secure connection to the chassis.
The resistor is the same. Probably nothing wrong with the original. I'd probably just solder an extension lead onto the original. You might even consider another ring lug for the resistor, rather than soldering it directly to the cap negative terminal. Flip a coin.
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Get rid of those loops on the green wire. Probably only needs to be about 1" to 1.5" long. Also use a kep nut or at least a star lock washer. That green wire needs a really secure connection to the chassis.
The resistor is the same. Probably nothing wrong with the original. I'd probably just solder an extension lead onto the original. You might even consider another ring lug for the resistor, rather than soldering it directly to the cap negative terminal. Flip a coin.
I will get a k-nut and shorten the green wire.
Could I solder the green wire on that lug, then run the green back to an empty on the terminal strip? If so, I could land the resistor and the black/yellow on the terminal strip as well.
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There are lots of ways you can do it but when you're done, the cap can negative terminal, red/yellow PT wire, and that 150Ω resistor must all have good electrical/mechanical contact with the chassis, preferably all at the same chassis point.
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...good electrical/mechanical contact with the chassis, preferably all at the same chassis point.
That makes sense, more connections is more potential failure points.
I may attach the red/yellow on the negative terminal... I was hoping the new 150ohm resistor would reach the terminal strip, no joy on that. Or perhaps wait another day (or two) for the terminal strips to show up in the mail and install a new one. That would help unclutter the area a bit.
Speaking of the existing terminal strip...
The two yellow wires and one red/black wire used to connect to the tuner chassis plug, which I removed.
How would you deal with wires, coming from the PT, which are no longer being used?
Also, is the circular resistor in the center of the terminal strip C63A/B?
Is that a left over component from the wall plug/fuse setup that is no longer in use?
The last attachment is an earlier photo that I marked up for reference to this post.
Thanks
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Don't mess with anything that you don't have to. Those unused PT wires ain't hurtin' anything.
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Don't mess with anything that you don't have to. Those unused PT wires ain't hurtin' anything.
Ok, I will leave them where they are. Can I remove the disk shaped cap in the middle?
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Are you asking for my permission?
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Are you asking for my permission?
hahaha ... no, more like your opinion, both would be nice! :icon_biggrin:
Two posts back I asked about the circular resistor in the center of the terminal strip. Is it C63 from schematic? Is it left over component from the wall plug/fuse setup that is no longer in use?
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I believe it's already out of the circuit since you changed the AC primary side. It "didn't" fail when we did initial 2 prong tests so for now just leave it. once you're jamin to the stereo, then you can decide how to clean up the leftovers
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Sounds good. I will remove the green wire 'jumper' between the cap can and terminal strip and connect the red/yellow to the cap can along with the 150ohm resistor and chassis ground. If that is all I need connected to the negative terminal on the can, I believe it is, then I will solder it and start figuring out how to connect the rest of the wires/caps/resistors back into place.
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.......Can I remove the disk shaped cap in the middle?
Muntzing (https://en.wikipedia.org/wiki/Muntzing)
Reach into a live TV chassis, snip out a part. If the TV keeps working, you did not need that part, and you can scold the designer who drew it in.
https://www.electronicdesign.com/technologies/boards/article/21771148/whats-all-this-muntzing-stuff-anyhow
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Muntzing... Hahaha! Thanks for the memory.
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Muntzing
Thanks for sharing, I love history nuggets! I was rooting for him until I read the line " The repairmen were happy to get all this repeat business, but eventually the customers figured out that a low initial cost was not necessarily the best investment ..." Does that mean he was snipping a bunch of non-frivolous parts?
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I did not get a chance to finish up today. The pictures below is where I left off.
The marked up photo depicts where I believe the 2200ohm 5W resistor should be placed and where I believe the 100ohm 10W should be reconnected.
The circle around the wire and two resistors is where I am a bit confused. They had been connected to the cap can at 'C52D' which was 50u | 25v.
ETA: The line from the 100ohm should be coming from the other side of the resistor...
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time to learn schematics!
make your pics match up with these pics.
your blue line points to where the R was originally, and still is, soldered, are you wanting to unsolder and move to cap?
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Just connect the two 47Ω resistors and the yellow wire to an unused lug on that empty terminal strip. You should have a single cap that needs to connect parallel with that big brown 150Ω resistor. Negative lead goes to chassis ground.
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your blue line points to where the R was originally, and still is, soldered, are you wanting to unsolder and move to cap?
No, my bad. See attached, this is where I believe the 100ohm R should connect.
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No, my bad. See attached, this is where I believe the 100ohm R should connect.
No it doesn't. You better study your pics and get it right. Otherwise, you may just blow up something. You are missing a big 2.2K/5W resistor. Where is it?
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No it doesn't. You better study your pics and get it right. Otherwise, you may just blow up something. You are missing a big 2.2K/5W resistor. Where is it?
I drew it into the last picture attached to post #125.
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OK. Now see the cap terminal with the two red transformer wires on it? The free end of that 100Ω/10W has to connect to the same terminal.
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OK. Now see the cap terminal with the two red transformer wires on it? The free end of that 100Ω/10W has to connect to the same terminal.
Like this? With the blue being the 2.2k 5W
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yes
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yes
Thanks. I will post a photo tomorrow when I get it all connected, but before I solder any of it together.
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something seems off
the 2 OT CT (reds) should be at the same point as the 100, 2.2k, and cap :dontknow:
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something seems off
the 2 OT CT (reds) should be at the same point as the 100, 2.2k, and cap :dontknow:
Yes, that's what he is showing. His blue blob is a 2.2K/5W. That half watt 2.2K comes after the big 2.2K.
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something seems off
His blue blob...
I will have an updated photo soon.
Any suggestions on a simple program to make schematics on my PC? I am running ubuntu based linux... I can run *some* windows programs on it, but prefer a native linux program when available.
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That half watt 2.2K
Thanks, the other one didn't have color codes :icon_biggrin:
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suggest some shrink wrap on the 100 ohm, the lead is long bare and close to places it shouldn't touch
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That half watt 2.2K
Thanks, the other one didn't have color codes :icon_biggrin:
Didn't need color codes. It was writ right on it. In big numbers. :icon_biggrin:
BTW, txtune, can't you make your new wiring look like this? Much neater IMO.
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suggest some shrink wrap on the 100 ohm, the lead is long bare and close to places it shouldn't touch
Yes, I am going to shrink wrap the long leads on several of these before I solder them on.
BTW, txtune, can't you make your new wiring look like this? Much neater IMO.
Let me verify my connection points are correct first, then I will clean it up. :new1:
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Do the photos in my previous post look correct, so far as connection points are concerned?
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Connections are correct, but jumper terminal U and O together. And reroute those wires to be close to the chassis, nor running on top of any resistors.
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Connections are correct, but jumper terminal U and O together. And reroute those wires to be close to the chassis, nor running on top of any resistors.
Got it. Let me work on this 'punch list'.
Jumper cap can terminals U and O together with short piece of wire.
Run existing wires beneath resistors, closer to chassis.
Install heat shrink on long resistor leads that are in close proximity to any other metal surface.
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Pic...
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Pic...
Wow, thanks Sluckey! That is about as clear cut as it gets. I thought I would finish up on Friday, but the phone starting ringing and I got caught up with work.
What software did you use to create that?
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Visio
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Pic...
See attached photos. What is suitable method to attach the 47uf cap leads to the 150ohm resistor leads? Short pieces of wire??
I will add some heat shrink to the 150 resistor as well.
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I'd put the cap like this. I also recommend to remove the big brown resistor from the cap can, put a ring lug on the end and bolt it to the chassis using the same screw that the green wire is attached. Even better, solder a green wire to the end of the brown resistor lead and put one ring lug on both, then solder the other end of the green wire to the cap can. Much neater IMO.
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Much neater IMO.
Will do, what about the yel/blk coming from the PT? Put a lug on it and bolt it down too?
Glad I invested in the solder sucker gun!
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Ain't no yel/blk coming from the PT.
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Ain't no yel/blk coming from the PT.
Red/yellow is what I meant to say. Put a lug on it and place it under the keps nut with the green wire and brown resistor lead?
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Many ways to skin a cat.
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Many ways to skin a cat.
Got it, I will go ahead and land the red/yel at the chassis ground with the others. Try to keep them as consolidated as possible.
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Crimp ring lugs are fine but I prefer these solder lugs...
https://www.tubesandmore.com/products/solder-lug-6-or-8-hole-locking
http://sluckeyamps.com/hammond/closeup.jpg
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Crimp ring lugs are fine but I prefer these solder lugs...
https://www.tubesandmore.com/products/solder-lug-6-or-8-hole-locking
http://sluckeyamps.com/hammond/closeup.jpg
I have some of those, that would look much better. I will redo this in the morning.
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Looks good as is.
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I'm obviously a bit late to the party, but as I just redesigned a Stromberg Carlson, I thought I'd throw in my 2cents worth.
Using the original transformers and chassis, I redesigned the unit as a simple stereo SE amp, almost like a pair of Champs, with a 12AX7 in the preamp stage followed by a TB Princeton style tone stack, followed by a 12AT7 PI. Then, with the JJ6V6S power tube for each amp, I had 7 tubes total, including the 5U4 rectifier. I also added a simple balance control just before the power tubes. Then I added a bluetooth input for stereo audio.
I found it worked quite nicely, but I couldn't get rid of distortion in the speakers. After much head-scratching, I changed the old alnico speakers for some old Eminence ceramics, and the distortion disappeared - almost. (I like alnico, but the older magnets apparently loose their zip, and the result was distorted sound.)
Trouble-shooting the distortion: The OTs measured different passive impedances, and each side sounded different, so I knew they were no longer a balanced pair (if they ever were:). So I screwed around with replacing them, first one side, then the other. I used Hammond 125CSE trannies from Tubes and More. They were much less expensive than Ultralinear audio trannies, and while they may be designed for an instrument amp, the specs are good. When I replaced the weaker of the original OTs, the sound improved on that side, so much so that I then realized that the side using the remaining original tranny still had distortion. So in went a second 125CSE, and the thing is now really singing. And very loud for a small amp. JJ6V6S has a max dissipation of 14w, and I have it biased down a little to around ten watts per side. It's really thumping.
I love re-using old gear, but I must have rebuilt that amp a dozen times, trying to clean up the sound. Lesson learned.
I have found something interesting about SE stereo amps, which also has me guessing. It is easy to exchange the OT leads on a mono SE amp when we get NFB howl. But I have found - having rebuilt this amp so often - that one side is usually okay, but the other side howls. The problem that arises is that I cannot change the howling tranny's leads without incurring stereo phase cancelling. I have been unable to find anything online that deals with this issue. I guess it doesn't pop up too often, but if anyone can help me out, I'd be one happy camper.
Best to all, and Happy Thanksgiving.
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The problem that arises is that I cannot change the howling tranny's leads without incurring stereo phase cancelling. I have been unable to find anything online that deals with this issue. I guess it doesn't pop up too often, but if anyone can help me out, I'd be one happy camper.
Flip the two wires at one speaker cab.
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Looks good as is.
Thanks Sluckey, I may redo the green wire... I don't like how it's pulling away from ring lug. So long as the attachments look good, I will clean it up and solder it in place and see what happens when I turn it on.
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Flip the two wires at one speaker cab.
[/quote]
OMG. As simple as that. Thank you Sluckey!
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...I just redesigned a Stromberg Carlson...
Do you have any photos you can share? I am interested to see other ASR-120s.
Have you seen this blog?
https://origaminightlamp.blogspot.com/2020/04/stromberg-carlson-asr-120-stereo-tube.html
https://origaminightlamp.blogspot.com/2020/05/stromberg-carlson-asr-120-stereo-tube.html
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Looks good as is.
See attached. Last look before I fire it up. Does everything look correct? I know it's not neat...
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Thanks for the blog link, txtune. Very interesting.
I will put some photos together at some point; documenting my builds is probably my least fav part of the process, but it has to be done for learning purposes. And so I don't forget what I did:). But what I ended up with looks nothing like that clean machine in the blog. Your work looks fairly neat, as far as I can tell.
I usually fire up an amp for the first time using a variac style transformer, bringing it up to about 70vac for a few minutes. Then, if nothing smokes or crackles and pops, or hums too loudly, I'll bring it up to 120vac before checking voltages.
Good luck with it!
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Your work looks fairly neat, as far as I can tell.
Are you sure you are looking at my work. :w2: :laugh:
Thanks! I look forward to comparing notes and photos.
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now the hard part, which song to play 1st :icon_biggrin:
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now the hard part, which song to play 1st :icon_biggrin:
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No more humming noise! Also, no fire or smoke!! :icon_biggrin:
The sound is extremely flat. This time around I had it connected to some larger speakers, Klipsch Heresy model to be exact... not sure if that could be an issue.
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all the EQ has to be done "up front", i would start there.
does it get loud? left and right side ~~~ =? one side "flatter" than the other?
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all the EQ has to be done "up front", i would start there.
Up front??
does it get loud? left and right side ~~~ =? one side "flatter" than the other?
It will get loud. Both sides are equally flat.
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No more humming noise! Also, no fire or smoke!! :icon_biggrin:
The sound is extremely flat. This time around I had it connected to some larger speakers, Klipsch Heresy model to be exact... not sure if that could be an issue.
I'd say you're done. It's supposed to sound flat. It's only a power amp. You need a stereo preamp to add the good stuff.
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3/4 my music is digital, computer stored n played. took me some time tweaking the music player to get the EQ the way I liked. Even after that I wasn't happy with bass, so I split the signal and fed mono to a SS bass amp driving my Altaic Lansing 15". my Klipsch bookshelf's run the stereo n we're all happy :icon_biggrin:
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Does this tuner from the ASR120 have the preamp built into it?
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Does this tuner from the ASR120 have the preamp built into it?
most likely
EDIT... Let me clarify. There is no preamp on that SR-130 tuner chassis. The tuner has a high enough output to go through a passive tone control to drive the ASR-120 power amp. And the phono input to the tuner is also high output/poor quality ceramic pickup that's also able to go through the passive tone controls to drive the power amp.
Do you have the tuner chassis? If so and you want to use it you will have to rewind back to the point where you removed that multi-pin plug and wires. The tuner was powered by the power amp. IMO, you are way past the point of no return. I sure ain't up to any rewind. I would forget about that tuner and look for another tuner/preamp that can plug into the RCA jacks you installed.
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Reviewing all your pics and I just spotted an error you made long time ago when you were installing the RCA jacks and input caps. You put 470Ω (yel-vio-brn) resistors on the original input jack. Those resistors should be 470K (yel-vio-yel)
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look at page 1 reply #41, the "extra credit section"
you'll see 2 black arrows for IN, the plug on right is the OUT to the PA section you have.
you'll have to "untangle" the rotary switches, i did my time with them while you were eating Cap'n crunch n watching sesame street :icon_biggrin:
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i did my time with them while you were eating Cap'n crunch n watching sesame street :icon_biggrin:
:laugh: :l2:
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Reviewing all your pics and I just spotted an error you made long time ago when you were installing the RCA jacks and input caps. You put 470Ω (yel-vio-brn) resistors on the original input jack. Those resistors should be 470K (yel-vio-yel)
The two in these pictures?
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I would forget about that tuner and look for another tuner/preamp that can plug into the RCA jacks you installed.
I thought about it some more and came to the same conclusion. This project is enough for me as is.
After connecting a very basic pre-amp to the RCA jacks, the treble must be turned to 25% and bass to 100% for the music to sound 'normal'.
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then you're there, the dial goes to 10, it sounds normal, what more do you want :icon_biggrin:
i'm using the non-tone control version of your pre to drive my 20yr old powered computer speakers.
do an experiment;
connect your meter, set to VAC, across one speaker
find an annoyingly long "held note" and loop it, or just hit play over n over
try and "ballpark" an average reading while that's playing max volume use just your amp, no pre
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Put the correct resistors on the input jack and you may like it better. Most likely be louder too.
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Put the correct resistors on the input jack and you may like it better. Most likely be louder too.
Will do. Thanks for pointing this out!
I am not sure what that connection point was for, where the resistors and caps connect... it's not being used on the top of the chassis any longer. I was thinking a small terminal strip, would be a cleaner place to land those wires, caps, resistors... it would also free up that opening in the chassis for something else down the road.
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then you're there, the dial goes to 10, it sounds normal, what more do you want :icon_biggrin:
heh ... I will put the meter on it and let you know what I find. What am I looking for?
I still have the caps left from the 'kit' I purchased early on. They replace the six 400v film caps on the board toward the front. Is that an 'eyelet' board? What would be a suitable replacement material to rebuild that board completely? Could I use a turret board??
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I am not sure what that connection point was for, where the resistors and caps connect... it's not being used on the top of the chassis any longer.
The audio output from the SR-130 tuner connected to that 3 pin socket.
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since you don't have a scope or sig-gen, we're cheating.
if you take the Vac value, square it, then divide by 8 = very approximated power out measurement
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The audio output from the SR-130 tuner connected to that 3 pin socket.
If I moved everything to a small terminal strip, per the attached drawing, could I do away with that 3 pin socket?
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Can be simpler?
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Can be simpler?
Nice! I left out one wire though, the white wire coming from the 'board' ... it is tied together with the chassis ground and the ends of the resistors. See attached.
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Don't forget the cap and resistor must connect to pin 7. Solder the white wire directly to that bent up chassis tang.
EDIT... THE RESISTOR VALUE IS 470k.
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EDIT... THE RESISTOR VALUE IS 470k.
Updated drawing.
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Don't forget the cap and resistor must connect to pin 7. Solder the white wire directly to that bent up chassis tang.
EDIT... THE RESISTOR VALUE IS 470k.
It sounds a LOT better with the correct resistor. Thanks!
I really want to redo the circuit board. Would you use a turret board and start over?
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I'd get some mineral spirits, denatured alcohol, and a variety of small brushes, ie, tooth brush, acid brush, 1" paint brush, etc. and clean it. That's all.
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I'd get some mineral spirits, denatured alcohol, and a variety of small brushes, ie, tooth brush, acid brush, 1" paint brush, etc. and clean it. That's all.
Would you not replace the caps?
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I would not.
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....Would you use a turret board and start over?
No.
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I'd get some mineral spirits, denatured alcohol, and a variety of small brushes, ie, tooth brush, acid brush, 1" paint brush, etc. and clean it. That's all.
What is the best description of the board on this amp? Is it simply referred to as the 'circuit board'? What material would you guess it is made of?
The amp ran all day today, connected only to the FM tuner and a pair of Heresey speakers. All of the Stromberg Carlson tubes are still working, as best I can tell. The tubes may not be 'original' from when my grandfather purchased the stereo in the 1950s, but they are all SC brand.
I get where you are coming from - 'don't fix something that ain't broke'. So I won't... I would like to clean up the wiring a bit and will try to gently clean that board off without removing it.
What is the goo that has run across the circuit board and, also, what is the wax looking substance that appears to be 'growing' on some of the wires like mold?
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...All of the Stromberg Carlson tubes are still working, as best I can tell. The tubes may not be 'original' from when my grandfather purchased the stereo in the 1950s, but they are all SC brand. ....
Stromberg Carlson never sold tubes over the counter, certainly in the period this amp was made. Those were installed at the factory. They were not made by S-C: every hi-fi maker contracted with the big 5 tube makers for own-logo tubes.
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That's all the more impressive if these tubes are original.
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Glad you're clicking along, I landed in your state, it's FRIGGIN colder than MI!!! the upside I landed in a place time forgot, no cell/WIFI for 30miles in ANY direction!! :icon_biggrin:
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Glad you're clicking along, I landed in your state, it's FRIGGIN colder than MI!!! the upside I landed in a place time forgot, no cell/WIFI for 30miles in ANY direction!! :icon_biggrin:
Yep, my weather station is reading 44 degrees at this moment. If you don't like the weather in Texas, wait five minutes and it will change. :icon_biggrin:
Did you drive? What part of the state are you in? Be safe!
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Is that amp working yet!
Garner SP for 2 weeks, well 1 now. 7miles from Leaky, 37miles from Uvalde
it's sunny and 72 so I'm happy, the 32 at night is fine, i'm asleep in a 10 degree bag :icon_biggrin:
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Is that amp working yet!
Garner SP for 2 weeks, well 1 now. 7miles from Leaky, 37miles from Uvalde
it's sunny and 72 so I'm happy, the 32 at night is fine, i'm asleep in a 10 degree bag :icon_biggrin:
Yes, it's been working for several weeks. I would like to add a volume control to it at some point.
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Did you clean that board and cruddy wires?
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Did you clean that board and cruddy wires?
I got the cleaning supplies today. I also plan to tidy up the wiring I originally installed.
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Did you clean that board and cruddy wires?
I decided to create a layout before I get into the board cleaning, see attached. Still working on it, about halfway through the board.
In the case that something breaks, what would be a good way to rebuild this board? -OR- If you had to rebuild this board from scratch how would you do it?
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Is that amp working yet!
Garner SP for 2 weeks, well 1 now. 7miles from Leaky, 37miles from Uvalde
it's sunny and 72 so I'm happy, the 32 at night is fine, i'm asleep in a 10 degree bag :icon_biggrin:
i used to tear through those parts on my speed triple and falco in the triple digits - some nice twisties in that area. garner state park is beautiful. enjoy your visit.
--pete
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I believe the board is correct in this layout.
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enjoy your visit.
Thanks Pete, I did, and If I had my rally car, I woulda, but with the redneck camper, it's all I could do to keep it upright at 75mph :icon_biggrin:
so did you get volume added yet or are you still playing with computer graphics :angel
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I believe the board is correct in this layout.
What are your plans for the bottom side of the board?