Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on December 30, 2013, 07:17:24 pm
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I have this monster of a Marshall bass amp that has no filament voltage. No B+ as well. I am checking to see that it is wired for 120 A/C.
The pilot light is working. Can someone explain the toridal power transformers to me? I have the schematic. No color code wiring scheme to go by
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In general, a torioid is no different than a conventional tranny, just a different form factor based upon the superior magnetic properties of the toroid. The pilot, to me, looks like it runs off the filament voltage so that's sort of odd. With power off, just check continuity across windings as you would on any other suspect tranny. Does it look like it was messed with? (I'm just asking questions to jog your thinking)
Somewhat puzzled as to why you would suspect a different primary voltage. Did it not work at some point here in the US? Think someone changed it?
That sucker is a welder.
If the primary fuse is good, I would check any interconnect ribbon cables and the like.
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Well the amp was shipped from England and bought as not working. It is factory marked 220 VAC on the main input panel. Most of the connectors seem very loose (wiggly). Could be my imagination. It look very clean as new and un messed with. Fuse was blown when it came in. All screens and grid r's good
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That sucker is a welder.
In my experience with welders, I have seen a lot of problems associated with the input links set incorrectly, or loose.....even from guys who swear that they know what they are doing....
Since you have issues coming out of both xfmrs,,,B+ and filament (confirm that after replacing fuses),,,,, I want to believe that your problem IS on the primary side
I cant tell from the schematic if the pilot light would still work if T (thermostat) was tripped
I'm just a scrub R+R guy, but I did stare at the schematic for a 1/2 hour :huh:......(long enough to notice the 12AU7 PPI CF driver tube :icon_biggrin:)
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What does RL1 do?
I'm suspecting that it de-energizes the HT PT until a speaker is plugged in.
That does not explain no tube heat.
I still don't see any pilot light.
Links are vital!! While 117V on a 230V connection won't blow-up, there's ways to put those links that will short-out the power line.
You should find 117VAC *across* R2 when just plugged-in, across C6 when turned-on, and across C5 when HT is engaged (which needs RL1 pulled-in).
If it is "overheated", there is 117VAC *across* T (thermostat). These things can go bad (open). Also their lugs can lose contact. (Hacked a lot of these when I used to live with Mr Coffee.)
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I still don't see any pilot light.
Is this it PRR?
Page 1 bottom left....seems to be in the heater path
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I will get back on this tommorrow. I'll check those voltages at the reference points given PRR.
I got food posioned by a fish sandwich. Yuk
Cant stay away from the amp/ Oh well. Here goes:
120VAC @ R2 1 Meg resistor 1.675 VAC across other side of R2 1 Meg
120VAC @ C6 when turned on / 1.725 VAC @ other end of C6
C5 3.92 VAC when Standby engaged. 1.495 VAC on other side of C5
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120VAC @ C6 when turned on / 1.725 VAC @ other end of C6
I think you should be seeing the same 120VAC at C5 that you see at C6 with the standby switch engaged.....maybe jumper/bypass RL1b?
I would also check IR1, which I believe to be a thermistor (current limiting)......should measure approx. 2.5ohms on it's own (?)
PRR, I'm just throwing this stuff out there in an attempt to learn, with your guidance.....please bear with me plexi, I think I'm doing Ok....if nothing else, my "help" should make for a good laugh.......
good luck sir, it's off to the NYE celebration with my wife :help: :icon_biggrin:
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IR2 thermistor is good and i have 120VAC on both sides of it
1R1 thermistor 3.80VAC and across 3.11VAC
Continued:
W2-W3-W4-W7 all have 120VAC on them
W6 has 3.56VAC when standby switched on / RL1B i am looking at now
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1R1 thermistor 3.80VAC and across 3.11VAC
wait for PRR to confirm/ deny....but I'll put this out there
If my value of 2.5 ohms for that thermistor is close to correct, then you are passing approx. 1.2 amps through IR1? (@3.11VAC drop)
:think1:
I'm still tying to figure out where W26 , W27 connect.... :dontknow:
RL1a (coming off of W26 @ TR1) is our coil for RL1 (b).....right?
(maybe a bad TR1?)
If you bypassed RL1b contacts you would get 120VAC through IR1 to C5,,,,,and therefore have your B+
Are you checking preamp tubes (DC) or power tubes (AC) for filament voltages?.....(switch your meter?)
sorry plexi, just random thoughts while I wait for my wife to "get ready" :rolleyes:
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Oh no, all random thoughts are more than welcome. Thats where we have to start anyway. Your a big help in me confirming the transformers health. I have thought about jumping W7 RLB1 (120VAC) over to W6. But i need to see some heater filament voltage first i believe. I think i have to have RLB1 voltage over to W6 to make the heater filament voltage complete and working. Look at W14 & W17.
I have 3.20 filament voltage at W17. I now need to see 3.2VAC +- on the W14 terminal. That would happen if i jump RL1B W7 to W6.
But i want to wait yet for more input before i fly blind and try this. What if RLB1 is shorted or something. I dont want to make matters any worse.
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More random thoughts....
- RL1 is a simple make/break relay.....with 60V fed through coil RL1a,,,, RL1b should close and complete our 120VAC to W6 (we agree).......
- W26 is just a shared ground path and W27 is our supply V for that relay, and I have to assume that it is fed off of the xfmr that isn't controlled by the relay.......so you should see 60V(ish) (if TR1 is OK) @ that coil (RL1a) with mains switch engaged
-That coil needs a path to ground to work ...... the next thing I would look at is the shorting jack speaker connectors, which serve as the path to ground in that speaker switching circuit PRR mentioned earlier...........right?
- Without a speaker plugged in(or a faulty jack / contacts), the coil won't energize
- If you jumper RL1b contacts, you will just be bypassing the 'speaker plugged in' protection circuit (and see if the amp works)
- At that point you should know either relay coil / contacts is bad, speaker jack is faulty, or TR1 is bad........heck, you might be able to just switch speaker outs and solve the mystery .....just try plugging into the other speaker jack
Good luck sir, and Happy New Year!
I'm glad to have the chance to get these thoughts out (while everyone else is enjoying the holiday), and possibly be corrected or confirmed, and possibly learn something.
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I don't like to go back and edit posts...but there is something I would like to let PRR know so he doesn't think I am a knucklehead.....so instead of editing the post to "make myself right", I'll just explain....
In post #5 I pointed out the pilot light....but I only found it right after PRR said he didn't see it either...sooooo, of course it wouldn't be lit if T was open........I should have written that then
I feel better now
Except, I'm still upset that there is no designation for where W26 (or W27) originates....I hate missing puzzle pieces ...can you trace it out physically and tell me where it goes?
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> I hate missing puzzle pieces
I hate the whole dang drawing. MUCH too messy and broken-up.
I also do not like builds which have more connectors than parts. Both for clarity, and because connectors go bad a LOT. IMHO this is a build-only design, not repairable (not any sane way).
I think you are doing better than me.
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I think you are doing better than me.
:laugh: Well there ya go SG, your doing good.
I was looking at it too, very messy and very chopped up alright.
Brad :icon_biggrin:
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I think you are doing better than me.
:laugh: Well there ya go SG, your doing good
Yeah,,, I guess :think1:,,,I kinda wish he woulda said that last year....it's gonna be hard to top that in 2014 :icon_biggrin:
So plex,,, check the speaker jack switching contacts, and verify 60V @ RL1a with the mains switch engaged and a speaker plugged in
I wouldn't hesitate to jump out RL1b.....typical relay failure is either bad coil or points stuck closed
If you're 100% sure that you've got the input jumper links correct, there should be nothing scary about it.........to test further, of course
I would be much less likely to believe that the xfmr is bad, unless somebody did something really stoopid
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I kinda wish he woulda said that last year....it's gonna be hard to top that in 2014 :icon_biggrin:
:laugh:
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I think you are doing better than me.
:laugh: Well there ya go SG, your doing good
Yeah,,, I guess :think1:,,,I kinda wish he woulda said that last year....it's gonna be hard to top that in 2014 :icon_biggrin:
So plex,,, check the speaker jack switching contacts, and verify 60V @ RL1a with the mains switch engaged and a speaker plugged in
I wouldn't hesitate to jump out RL1b.....typical relay failure is either bad coil or points stuck closed
If you're 100% sure that you've got the input jumper links correct, there should be nothing scary about it.........to test further, of course
I would be much less likely to believe that the xfmr is bad, unless somebody did something really stoopid
Ok i will verify the 60V @ RL1A with the mains on and speaker plugged in tommorrow. I have it off my bench right now.
Man this thing is heavy!
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Ok i have it back on the bench. Back in a few minutes------------
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RL1b is now jumped and C5 has 120 VAC with standby engaged
No A/C voltage at RL1a / D5 or TR1 with speakers connected
I do have -27.46 VDC at these points though :think1:
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How about filament or B+ voltages?
No A/C voltage at RL1a / D5 or TR1 with speakers connected
Should be DC there....and 27.46 is a good sign
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No filament voltage on W14. Only on W17 to power tubes pin 2
No preamp filament voltages at all
No B+ volltage. Just 100VAC from the RL1b jump with standby on
And i thought the TSL 2000 was the worst design of all time. At least the TSL has a schematic you could read
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No filament voltage on W14. Only on W17 to power tubes pin 2
No preamp filament voltages at all
No B+ volltage. Just 100VAC from the RL1b jump with standby on
OUCH......now I'm in trouble... :sad2:
Input links, input links, input links.......that's all I got
I just don't want to believe the xfmr is bad :huh:
What do you get if you measure AC volts from W17 to W14?
What do you get across IR1 now?
Check F1 fuse on secondary, labeled T6.3A....
If you read the part I erased you'd know I'm obviously distracted by the Flyers game.....sorry about that one :undecided:
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I just don't want to believe the xfmr is bad
Me neither!
What do you get if you measure AC volts from W17 to W14?
3.200 VAC
What do you get across IR1 now?
1.65VAC & 20.20VDC
Both thermistors are good @ 2.0 ohms and are passing current
Maybe marshall has a service schematic? It looks like this schematic is one big puzzle.
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Can you assure me that the input links are perfect?,,,so I can stop obsessing about them,,,sorry to ask again
Now that you're seeing 120VAC @ C5, it has to get through the correct links to make the magic happen on the secondary.....
I'm afraid that if they are set right, and were still scratching our heads,,,,this may be bigger than me
Maybe marshall has a service schematic? It looks like this schematic is one big puzzle.
Yeah.......unfortunately I don't see anything on the net
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What AC volt reading do you get from:
W15 to W16?
W15 to W23?
W16 to W23?
W6 to W7?
W12 to W13?
I hate failing.....If I had it in front of me it would be tough to walk away.... :BangHead:
If the links are right and you've got 120VAC through to C5 and C6, the secondary AC voltages "should be' fairly obvious
Good luck man,,,,I feel for you :sad:
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Can you assure me that the input links are perfect?
No! Thats why i wanted to check the wiring to make certain that it is wired for 120VAC instead of 220VAC EURO
I check the fan on low and high speeds. It seems to rotate very slowly on low speed. Like i almost have to give it a push with my finger to get it going. High speed is faster but doesnt blow any hardcore wind or sound like it is hauling azz
I shouldnt assume this but it did come from England and so i need to confirm the voltage mains wiring. This is going to be a long haul
Be right back with those voltage readings/
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With Standby Engaged/
W15 to W16 - 119VAC
W15 to W23 - 119VAC
W16 to W23 - 0VAC - 3.20VDC
W6 to W7 - 0VAC - or VDC
W12 to W13 - .045VAC
No i know what you mean. Sometimes the obvious slides right by me. All your thinking has been a big help :worthy1:
The schematic is almost Greek to me
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Can you assure me that the input links are perfect?
No! Thats why i wanted to check the wiring to make certain that it is wired for 120VAC instead of 220VAC EURO
I check the fan on low and high speeds. It seems to rotate very slowly on low speed. Like i almost have to give it a push with my finger to get it going. High speed is faster but doesnt blow any hardcore wind or sound like it is hauling azz
I shouldnt assume this but it did come from England and so i need to confirm the voltage mains wiring. This is going to be a long haul
Be right back with those voltage readings/
Yup,,, this all points to those jumper links being incorrectly set....
The fan spinning slowly means it's not getting full voltage...the missing voltages, low voltages, relay not energizing......all makes sense
What do the links look like? (pics?)...I've searched for pics but cant find any, and no help from Marshall either
I'm pretty confident that if we get that straightened out, it's gonna do it :icon_biggrin:
The schematic is very similar to what I see in welding machines, so it doesn't bother me that much......those links have caused perfectly intelligent grown men to blow up perfectly good $3000 welding machines........that's why I keep going back to that......I'd be thrilled to know I actually helped you figure this out :thumbsup:
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Just in case you're still having trouble seeing it,,,here's the connections that you need to verify
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Checking now/
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Ok all links are confirmed and wired correctly! Interesting and curious possabilities!
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zzzzzzzzzzzzzzzzzzzzz...... :offtheair:
I'm hoping to wake to news of your success.....
it will take the sting off of 6 fresh inches of snow and a Flyers loss
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No! Thats why i wanted to check the wiring to make certain that it is wired for 120VAC instead of 220VAC EURO
Sorry man,,,I don't know why I thought we were past that......I had assumed that we had originally found it set for 220VAC and at some point you had switched the links around to be correct for 120VAC :dontknow:
Ok all links are confirmed and wired correctly! Interesting and curious possabilities!
Does that mean that they were wrong and you now changed them and got them right?
Or were they set right all along?
Kinda like an Abbott and Costello skit at this point :l2:
Abbott & Costello: "Two Tens for a Five" (http://www.youtube.com/watch?v=f7pMYHn-1yA#)
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No they were set right all along. I just got confused looking at all the links. There are so many links. There are some that have the same link numbers on the power supply capacitor board as the back board attached to the rear of the chassis where all the links connect. Im all linked out. I'll get some pics up later today.
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"Here, here's 2 tens gime back my 5."
:l2:
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No they were set right all along. I just got confused looking at all the links.
Well, that blows.....that was the only hope I had :embarrassed:
I don't think there's any good explanation for why were not seeing proper secondary voltages,,,,,except bad xfmr (s)
I would triple check those links, and then triple check them again,,,,,,but that's just because I have a problem.....I don't believe what my eyes tell me sometimes :huh:
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I don't believe what my eyes tell me sometimes
Isnt that the truth.
I will go back and look at it later. I know it's linked to the links of the link that goes to the links that link the links to the links that link the whole dam thing up* :l2:
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I know it's linked to the links of the link that goes to the links that link the links to the links that link the whole dam thing up* :l2:
:l2:
Your a brave man and I believe you'll fix it but man what a pain.
Brad :w2:
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Your a brave man and I believe you'll fix it but man what a pain
I dont know about that Willabe. Im getting tired of amps made of left over parts
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Im getting tired of amps made of left over parts
:laugh:
Yeah I don't blame you, I don't think I'd want to poke around in there.
But we've all seen you fix a (good?) number of PCB amps among other amps that were strange also as in finding some weird problem. You always fix it in the end though.
Brad :icon_biggrin:
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Thanks Brad. We have no other choice but to live and learn in this business. What the heck it's fun to (i think?)
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What the heck it's fun to (i think?)
I was having fun, until I realized I wasn't going to WIN :sad2:
I'd still love to see pics of the monster that got me......
I'll hang em up on my wall to remind myself that I'm not as smart as I thought I was.......(my wife is right,,,again)
AND...
If I crack open an amp and there's a PC board in it,,,,close it up, give it back, and get back to doing something constructive with turrets :icon_biggrin:
LIFE'S TOO SHORT
If you must continue on......I'd probably mark and disconnect all secondary connections and check voltages that way....
It's the only way to confirm the xfmr is bad.......... ( :dontknow: ,,,,those toroids are pretty robust).....maybe a short on the link board?
:BangHead:
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...I'd probably mark and disconnect all secondary connections and check voltages that way....
It's the only way to confirm the xfmr is bad.......... ( :dontknow: ,,,,those toroids are pretty robust).....maybe a short on the link board?
+1
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I have this monster of a Marshall bass amp that has no filament voltage.
Do you still have no filament voltage?
If so, use this drawing to fix it.
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I have this monster of a Marshall bass amp that has no filament voltage.
Do you still have no filament voltage?
If so, use this drawing to fix it.
Fantasticola Steve. No i have no filamnet voltage yet. Been doing satuday house work and should i say it (laundry)
Will get on it very soon and report back with my findings. Thanks again all of you. Maybe i should throw the marshall in the washer too?
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Maybe i should throw the marshall in the washer too?
:laugh:
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Threw in washer. Results
W22 & W19 = 94 VAC
W18 & W20 = 0 VAC
W12 = 3.20VAC
W13 = O VAC
TR2 is good
I stood up an noticed heat coming from the top of the chassis. I touched the small toridal transformer and it burnt me. It and the surrounding wires to and from it were so hot i could not even touch them for a second. I am surprised it is not on fire. I use a small fuse block with fuse to bypass the thermal switch. It gets the panel out of my way at the same time. Bad Transformer?
What is the big TT function and what is the smaller TT function. I know i can look and see but im lazy :w2: :icon_biggrin:
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I know i can look and see but im lazy
Well, in that case, maybe you should just throw it in the washer. :sad:
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I know i can look and see but im lazy
Well, in that case, maybe you should just throw it in the washer. :sad:
:think1: I know. Ha! It is the transformer that supplies the mains voltage for the power supply and heaters. Man it's been over an hour and it is still hot to the touch. I removed the mounting bolt nut pulled it off the chassis. I have not removed the wires yet until i get good pic's. I hope the new one has the same color coded wires. Have to call a place in Norwich England Monday. I will try Patrick @ MM first
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I touched the small toridal transformer and it burnt me. It and the surrounding wires to and from it were so hot i could not even touch them for a second. I am surprised it is not on fire..
That's like a big clue. Worth mentioning at the beginning of the thread.
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Well i had the chassis on it's side and the transformers were at the top of the chassis. I was sitting and checking the board itself. It wasnt until this afternoon that i stood up and felt heat hit my forehead as i leaned over the top of the chassis. Thats when i touched the transformer and chassis. Why didnt the mains fuse blow? Why didnt my lamp dimmer draw down? :dontknow:
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Threw in washer. Results
W22 & W19 = 94 VAC
W18 & W20 = 0 VAC
W12 = 3.20VAC
W13 = O VAC
TR2 is good
You should have 120VAC BETWEEN W22 and W19. If not, check links 7 and 10.
You should have 120VAC BETWEEN W18 and W20. If not, check link 11.
You should have 6.3VAC BETWEEN W12 and W13 only if primary voltages are OK and transformer is good.
Your cold transformer probably does not have 120VAC applied to the primary windings due to interlock relay or STBY switch or improper links. It may be normal for the other transformer to be hot. There's a lot of heater current flowing.
The 65760 transformer is for the heaters and other low voltages.
The 65765 transformer is for high voltages.
I would not call the transformers bad until you have measured 120VAC across the primaries.
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These are the voltages take between (across) each lead. Not from ground
The transformer was hotter than a power tube biased very hot. The chassis as well. Ive never seen a chassis get that hot. I do thank you for all your info and help.
W22 & W19 = 94 VAC
W18 & W20 = 0 VAC
W12 = 3.20VAC
W13 = O VAC
TR2 is good
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These are the voltages take between (across) each lead. Not from ground
The transformer was hotter than a power tube biased very hot. The chassis as well. Ive never seen a chassis get that hot. I do thank you for all your info and help.
W22 & W19 = 94 VAC
W18 & W20 = 0 VAC
W12 = 3.20VAC
W13 = O VAC
TR2 is good
You say TR2 is good. I ask, "What are you calling TR2?"
Your two readings for W12 and W13 'indicate' you are measuring in respect to something else. If you measure between W12 and W13 you only get one reading. BTW, W13 is connected to ground.
W22 & W19 = 94 VAC... This should be 120VAC coming from the power cord. However, W22 must pass thru IR2. I'm guessing that IR2 may be a thermistor that is higher resistance when cold and lower resistance when hot. This would prevent high inrush of current at initial turn on, kinda like a 'soft start'. IR2 may explain why there is only 94 VAC between W22 and W19. IR2 may need to be replaced. For testing purposes, you can put a jumper across IR2.
W18 & W20 = 0 VAC... This should also be 120VAC coming from the power cord. Since you have 94VAC across W22 and W19, you should also have 94VAC across W18 and W20. Unless LINK 11 is not properly connected or you have a broken wire. It should be really easy to find out why you have zero volts across W18 and W20.
I would pull F1 and F2 fuses while troubleshooting the filament circuit. Just measure the unloaded filament voltage across W12 and W13.
At this point you just need to get 120VAC from the power cord all the way to W18 and W20. If you do that, the filament voltage may come up to 6.3VAC.
I'd like to see a hi rez pic showing the line voltage selection LINKs(1 thru 12) for the two transformers.
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You say TR2 is good. I ask, "What are you calling TR2?"
TR1 & TR2 are thermistors that limit the in rushing current. Both TR1 & TR2 read 2 ohms and have good continuity across them with no wires on the board.
Thats what i was checking yeterday with heater filament voltage being only on W12 only. And i expected to see 100VAC + on W18 & W20 which would have in turn shown filament voltage on W13. Link 11 and all other links on the board show continuity as to there layout (traces) with no wires attached.
Let me put the transformer back on the chassis and wire it up and i will check the voltages again on W18 & W20. I tell ya all these spade connectors on the board all have to be re-soldered. There all pretty wiggly. Let be pull the back board off the chassis and see what the solder connections under the board look like. My continuity checking may be showing good only becuse i am putting preasure on each terminal as i test them
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Ok i pulled the board from the chassis and found a trace @ W13 & W16 smoked at W16 solder trace. Trace broken and cracked. No continuity. Going over more of the boards pics now to see if there are any other funny looking joints. I will get back to the mains power transformer after i get this boards issues sorted out.
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Back Circuit Board pic's. I dont see any other solder cracks or broke traces. Going to re-solder them all good/
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TR1 & TR2 are thermistors that limit the in rushing current. Both TR1 & TR2 read 2 ohms and have good continuity across them with no wires on the board.
There is no TR1 or TR2 on the schematic provided. However, there is an IR1 and IR2. Is that what you are calling TR1 and TR2? If not, please show me a TR1 and TR2 on the schematic.
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Ok i pulled the board from the chassis and found a trace @ W13 & W16 smoked at W16 solder trace. Trace broken and cracked. No continuity.
Both of those connectors are for the HT transformer. They have nothing to do with the LT/Filament transformer. Put your shotgun down and put your thinking cap on and do some logical troubleshooting.
I'm trying to get you to divide and conquer. Fix the filament circuit first. First, you should be able to take that cleaned up drawing I posted and find out why there's zero volts across W18 and W20. Second, you should also be able to find out why there is only 94VAC across W22 and W19. I can't see it taking more than about 5 minutes to clear those two issues. When you clear these two issues, you should have 6.3VAC filament voltage between W12 and W13, unless the LT transformer is bad.
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I'm trying to get you to divide and conquer.
This is how I work my way through the most difficult schematics.....beak the print down into smaller, more digestable pieces......I just didn't know how to explain it as well as sluckey has :sad:
Now that he has joined us, I have obviously bowed out (hopefully, gracefully)....
There's no reason for me to add to your confusion ........he's got it handled better than I could ever hope to, and I will follow along and learn what I can....
His methods are rock solid and if you continue giving him answers, I have all the confidence in the world that you WILL fix that thing
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Hey, stick around. I'm just trying to point plexi in a particular direction. Once he locks on I'm likely to sit back and let him run.
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Yes im sorry. I have been calling IR1 & IR2 / TR1 & TR2. Im thinking thermistors and they have stuck in my head as TR1 / TR2. I will rewire the mains transformer tommorrow after i finish re-soldering and putting the board back in place. Can i just test the power transformer itself on the bench right now or would it be better for it to be in place on the board?
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Hey, stick around. I'm just trying to point plexi in a particular direction. Once he locks on I'm likely to sit back and let him run.
Thanks for the "vote of confidence" sir (I'll take the liberty of taking it that way :icon_biggrin:).....
if you tell me to stick around, I'll do it................
That schematic was starting to get to me too, and I never wanted to pretend that I could definitely fix it from here...
I learned the value of a great picture tutorial when you came aboard (reply #44), and I will remember to use that technique in the future....
It looks just like the Miller/Lincoln troubleshooting I'm used to.
What's the deal with W14 and W17 appearing on the primary and secondary connections? (don't know if I've seen that before)
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Board back in chassis. Wiring mains PT up now. No i love it when Steve makes me think. Back in a bit/
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I will rewire the mains transformer tommorrow
There is no "mains" transformer. There is a HT transformer for B+. And there is a LT transformer for filaments and low voltages. The transformer that is drawn directly to the right of the mains switch is the LT transformer.
Here's how the power switches function... The mains switch applies line voltage directly to the LT primary which should bring up filaments immediately. The mains switch also sends line voltage up toward the HT primary to develop B+ voltages. But the line voltage has to pass thru interlock relay contact RL1b and then thru the standby switch before reaching the HT transformer. IOW, RL1b contacts must be closed and the standby switch must be closed before line voltage is applied to the HT primary. So, when you throw the standby switch you are actually sending line voltage to the HT transformer.
Can i just test the power transformer itself on the bench right now
Absolutely. In fact, since you have it disconnect, I highly recommend doing so. Here's what you need to do...
I'm assuming you are talking about the 65760 LT transformer. If you still don't know which transformer is which, now is a good time to learn, before testing the transformer. Refer to my simplified drawing as needed. Jumper W22 and W18 together and connect the black wire of a power cord to W22. Jumper W19 and W20 together and connect the white wire of that power cord to W19. Don't worry about the green wire in the power cord. Now turn your variac off and set the dial to zero and plug that power cord into the variac. Set your meter to read AC volts and connect the probes to W12 and W13 (6.3VAC secondary). Now turn your variac on and turn the dial up a little bit so that you have 12VAC out of the variac. The voltage on your meter should be approx. 0.63VAC. If no smoke, turn the variac dial up so that you have 120VAC out of the variac. Your meter should now read approx. 6.3VAC.
If you understand and follow the above procedure EXACTLY but don't have 6.3VAC on your meter the LT transformer is bad.
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What's the deal with W14 and W17 appearing on the primary and secondary connections?
The W14 and W17 that you see on the schematic that shows the secondary circuit are probably on a different subassembly. At least they better be!
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What's the deal with W14 and W17 appearing on the primary and secondary connections?
The W14 and W17 that you see on the schematic that shows the secondary circuit are probably on a different subassembly. At least they better be!
Yes they are different board assemblys. I am ready for more testing. Board and all connectors soldered solid and strong. Filament PT back in place and wired up/
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Here is pic with both seperate boards having W14 & W17 connections
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Yes transformer 65760 is filament transformer and the one i am taking voltages on.
I dont know what has changed from the voltages i took yesterday showing:
W22 & W19 = 94 VAC
W18 & W20 = 0 VAC
W12 = 3.20VAC
W13 = O VAC
Transformer back in amp and wired up
Voltage taken across these points tonight. Im so tired i cant think straight. Done to much today but still at it.
W2 & W5 120VAC
W22 & W19 60VAC
W18 & W20 60VAC
W12 & W13 3.230VAC
I will follow your directions in the morning and test the filament transformer. I had the transformer back in and wired up before i read your post
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W22 & W19 60VAC
W18 & W20 60VAC
W12 & W13 3.230VAC
These voltages are exactly half what they should be. I think the dual primaries are connected in series and the applied line 120VAC will split evenly across the two primaries. This can only happen if the links are wrong or the transformer wires are connected wrong. You must use links 7, 10, and 11 for 120V operation. If the proper links are installed then you have the primary wires (W17 - W22) messed up.
Since you only have 60V (half what it should be) on the primaries, the secondary is correctly showing 3.2V (half what it should be). That means the transformer is probably good. Now just get the primaries straightened out.
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Ok i am going back over the links now.
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Steve all the links are correct. I found a pic online of the wiring colors to confirm how i have this one wired. It is the same as when i got it in. Shouldnt W17 white wire have 120VAC on it? I have 60VAC.
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I agree with Sluckey, you have the primaries in series and they need to be in parallel.
Looking at the schemo in your 1st post if you look at the 3rd page, the 2 PT's in between them is a foot note box with numbers but no wire colors.
It reads; 115v: Fit Lk1, Lk4, Lk5, Lk7, Lk10, Lk11.
(Edit: I forgot Lk11, sorry.)
Problem is it shows as drawn all links hooked up, they should have shown 3 different drawings, 1 for each wall input voltage, ie, 100v, 115v and 230v.
(It's drawn with shorts too because it has all 3 link setups drawn at once, bad, bad, bad drawing!)
Because you don't know the primary color code you probable will have to disconnect ALL the primary wires on both PT's and do a resistance check to find the 0, 100 and 115 legs/taps. Then you have to follow the foot note for 115v wall voltage and ONLY make those connections.
Unless someone has a better idea that's what I would do. Unless you can find the wire color code somewhere, maybe Marshall would give it to you?
Brad :think1:
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You can't have Lk3 and Lk4 hooked up at the same time. Also you can't have Lk9 and Lk10 hooked up at the same time. :w2: :BangHead: :cussing:
Brad :laugh:
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OR you have 1 or more extra links hooked up and it's shorting out or doing something weird. There's a lot of strange possibilities with wrong links hooked up. :BangHead: :cussing:
That could be why 1 of the PT's was smoking hot.
Brad :w2:
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ONLY make those connections
Just what i have been thinking all along. Seeing the amp with all of the wires connected just didnt seem right. I mean if you are wired for 120VAC then you wouldnt have the rest of the wires for 230VAC operation connected on the board too. Im sorry if i have been giving you a hard time guys. My memory has been messing with me for the past 6 months pretty bad. I am forgetting the most simple things in an instant. Like how to spell CAT. Pull the ring skin off bologna and throw the bologna away standing there with the skin. Lol!!! Jeez*
I went to cook a corn dog and instead of cooking the corn dog i only put the mustard on the plate. But seriously i really thank all of you for the time and brain strain it takes especially trying to decipher a schematic like this with no wire color coding. The basics of the primaries shouldnt be this difficult. It's very hard to concentrate when you start following the links which also link to other terminals as well. Thats when i figured out that it does not mean a wire must connect to that terminal as well.
You can't have Lk3 and Lk4 hooked up at the same time. Also you can't have Lk9 and Lk10 hooked up at the same time
Exactly what i have been thinking. But the schematic is messing with my head. I know Steve simple diagram is the right way it should be wired up for 120VAC. But then i have to refer back to the marshall schematic to make sure that i am not linked as well to 2-3 other terminal links that tie into other wires. I have to decipher the transformer voltages and then make the connections per link for 120VAC. I'll get it eventually.
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Seeing the amp with all of the wires connected just didnt seem right. I mean if you are wired for 120VAC then you wouldnt have the rest of the wires for 230VAC operation connected on the board too.
It's very hard to concentrate when you start following the links which also link to other terminals as well. Thats when i figured out that it does not mean a wire must connect to that terminal as well.
But the schematic is messing with my head. I know Steve simple diagram is the right way it should be wired up for 120VAC. But then i have to refer back to the marshall schematic to make sure that i am not linked as well to 2-3 other terminal links that tie into other wires.
Yep, that's what's screwy with Marshalls drawing. They know better too, especially with such a big amp and with all those links! :BangHead: :cussing:
They should have made 3 separate PT drawings, 1 for each wall voltage situation, 100v, 115v and 230v.
(Look at my edit 3 posts back, I forgot Lk11.)
Brad :icon_biggrin:
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It reads; 115v: Fit Lk1, Lk4, Lk5, Lk7, Lk10.
Well, you left out LINK11. That's pretty important!
Guys, don't let these links mess you up. The schematic simply shows all possible links. BUT NONE OF THE LINKS ARE IN PLACE ON THE SCHEMATIC. It's up to you to take a pencil and color the LINKS that will be used for 115VAC. Then it should be clear. Crystal! (my best Jack voice) :icon_biggrin:
Silvergun made a drawing where he boxed in RED all the LINKS that need to be installed. If it ain't boxed in RED, don't install it! See reply #29.
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It reads; 115v: Fit Lk1, Lk4, Lk5, Lk7, Lk10.
Well, you left out LINK11. That's pretty important!
Yes thank you, I caught that and made an edit. :laugh:
The schematic simply shows all possible links. BUT NONE OF THE LINKS ARE IN PLACE ON THE SCHEMATIC.
Silvergun made a drawing where he boxed in RED all the LINKS that need to be installed. If it ain't boxed in RED, don't install it! See reply #29.
Ok, now I remember SG's boxed in red drawing, I'll go back and look at it.
Brad :icon_biggrin:
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Sluckey, I went back and looked at both your drawing and SG's and FWIW, I agree they look right.
The schematic simply shows all possible links. BUT NONE OF THE LINKS ARE IN PLACE ON THE SCHEMATIC.
Ok, I see it now, because W10-W15 and W17-W22 are not connected to the PT primaries. I still say it's a screwy way to draw it up bit I guess they did it that way because the wire connections around the links are always there, maybe even traces on the PCB?
Brad :icon_biggrin:
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:icon_biggrin: :laugh: :l2: :w2: :dontknow: :help: :sad2: :think1: :worthy1: :BangHead: :cussing: :BangHead: :worthy1: :think1: :sad2: :help: :dontknow: :w2: :l2: :laugh: :icon_biggrin: :w2: :laugh: :w2: :laugh: :w2: :laugh:
That sums it up! Never quit is what i say. The lunatic is in the amp! :laugh:
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:thumbsup:
GREAT job of getting to the bottom of it guys!!!!
I'm just a little too timid to be pushing people I don't really know.....
plexi, it was a pleasure getting to know you here, and I've learned a lot about "how to" help someone.....sorry I left out a couple key words that could've made this easier on you
If it ain't boxed in RED, don't install it!
9 words that sluckey so eloquently expressed for me :icon_biggrin:
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SILVERGUN you have been a big help. Any info is better than no info. It has been a pleasure as well here and thanks again for your input. I emailed Marshall to see if they have a voltage spec method to there colored wires in this amp. In any case i am taking a day off from this beast and will sort out the primary wiring.
Sluckey, I went back and looked at both your drawing and SG's and FWIW, I agree they look right.
The schematic simply shows all possible links. BUT NONE OF THE LINKS ARE IN PLACE ON THE SCHEMATIC.
Ok, I see it now, because W10-W15 and W17-W22 are not connected to the PT primaries. I still say it's a screwy way to draw it up bit I guess they did it that way because the wire connections around the links are always there, maybe even traces on the PCB?
Yes i was looking at the board while i was re-soldering all the push on terminals. There are traces all over under the board that are linked to the links. This amp is Bi-Polar
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I emailed Marshall to see if they have a voltage spec method to there colored wires in this amp.
Does that mean there are no identifying markings on the PT or leads, or connectors??? Nothing at all to tell you this wire connects to here???
Do the PT leads each have a separate terminal, or do the wires fit into a multi terminal connector that can only be plugged in one way?
I'd like you to pull the LT transformer and set it on the bench. Take several good pics that clearly show everything that is written on the body of the PT and the wires and the terminals.
This is probably not your case, but I have seen expensive transformers and big transmitting tubes that actually had the wire labels stamped into the insulation of the wires. Rather than seeing AWG bla bla, the writing on the wire told you where it should connect.
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No voltage info on FT other than part number. I pulled back the rubberized bottom pad but nothing there either. No markings or numbers on wire connectors. Wire gauge and 300 volt printed on wires themselves
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Connectors void of any numbers or letters, Camera battery charging. Trying to show the info on the wire itself
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What's up with the orange pics? We need to see the wire colors. Never mind for now though.
I can help you figure out which wire is which. Then you can connect them properly. It'll take longer to read the instructions than it will to actually figure it out. 30 minutes tops to get it hooked up on the bench if you understand what we will be doing. Wanna play?
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Yeah sounds good. Lets go for it. I am going to use a different camera from here out. Ready,Set,Go!
I know where the (3) Black wires connect. (2) are the filament wires to the fuse link and (1) is the (AC i believe)
I know where the (2) orange low voltage wires go
That leaves one of each: Brown / Gray / Red / White / Blue
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I'd isolate the pairs and 3x sets of the primary and secondary by resistance test.
Then to find the primary 3x set, ie, 0-100-115, do another resistance test. 100 and 115 will be closest together and 115 will be furthest from 0.
When you find the primary set you can carefully tape up the unused secondary wires and apply a low voltage to the 0-115 pair, say 1 to 10 vac to the primary and take a reading on the secondary wire pairs. That should tell you what's what.
Brad :icon_biggrin:
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Well, your pic shows (at least part of) the problem: Link 9 is connected (shouldn't be) and Links 10, 11 are not (should be). There may be others not depicted in the photo.
Cut all the f-ing links. Take bare wire and jumper 1, 4, 5, 7, 10 and 11 and no others. Then you should be good (assuming you can put the LV transformer back like it was).
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Well, your pic shows (at least part of) the problem: Link 9 is connected (shouldn't be) and Links 10, 11 are not (should be). There may be others not depicted in the photo.
Cut all the f-ing links. Take bare wire and jumper 1, 4, 5, 7, 10 and 11 and no others. Then you should be good (assuming you can put the LV transformer back like it was).
Filament transformer wires measured so far
:
Brown & Black = 1 ohm
Brown & Gray = 6 ohm
White & Red = 1ohm
White & Blue = 6 ohm
Red & Blue 6.7 ohm
Links 1-6
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Just in case you're still having trouble seeing it,,,here's the connections that you need to verify
I don't think the links do any thing as long as you only hook up the right wires where they go.
Guys, don't let these links mess you up. The schematic simply shows all possible links. BUT NONE OF THE LINKS ARE IN PLACE ON THE SCHEMATIC. It's up to you to take a pencil and color the LINKS that will be used for 115VAC. Then it should be clear. Crystal! (my best Jack voice) :icon_biggrin:
Silvergun made a drawing where he boxed in RED all the LINKS that need to be installed. If it ain't boxed in RED, don't install it! See reply #29.
Here's SG's highlighted drawing link, link pun intended. :laugh:
http://www.el34world.com/Forum/index.php?action=dlattach;topic=16480.0;attach=40709 (http://www.el34world.com/Forum/index.php?action=dlattach;topic=16480.0;attach=40709)
Brad :icon_biggrin:
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You told us several times that the links were right. They ain't. Also, of the links I can see, I'm guessing you have had a wire strap soldered in every link. If Marshall had wanted all of them connected, they would have just etched solid traces on the board. Hopefully you didn't kill the transformers. Put the transformer aside for a few minutes and fix'em now. If you don't understand about the links then take another pic showing all 12 links and I'll draw them in for you.
Here's a pic showing correct links for the few that I see...
EDIT... Added the rest of the fixed links.
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I said this earlier that the links in the schemo would cause a short. :BangHead:
HT and LT are the same so I didn't color both, short in purple, sends + to ground.
You can't have Lk3 and Lk4 hooked up at the same time. Also you can't have Lk9 and Lk10 hooked up at the same time.
Brad
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Heres the back of the board with traces going to links.
Pic #1 is Links 1-6
Pic"2 is Links 7-12
Ok i am working off your info now.
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I've just analyzed your links. Your photos show links 1, 3, 7, and 9 installed. Well, that's strapped for 230V. But you're line voltage is only 120V. That's why your filament voltage was only half what it should be.
Solder the six jumpers across the links we've been telling you to use. Look at my fixed pics. Then put the LT back in the chassis and connect the wires like they were.
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I've just analyzed your links. Your photos show links 1, 3, 7, and 9 installed. Well, that's strapped for 230V. But you're line voltage is only 120V. That's why your filament voltage was only half what it should be.
Solder the six jumpers across the links we've been telling you to use. Look at my fixed pics. Then put the LT back in the chassis and connect the wires like they were.
Ok im going to work now.
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You can't have Lk3 and Lk4 hooked up at the same time. Also you can't have Lk9 and Lk10 hooked up at the same time.
He didn't. He only had links 1, 3, 7, and 9 installed when he took those pics. That's the configuration for 230VAC operation.
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Links finished. Look at pic's. Connecting wires now back as they originally were/
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Alright! Moving forward now... :wink:
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Wired up. Ready to flip on and see filament voltage. Any other thoughts before i proceed? Bon Voyagee!
.
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Bringing up on Variac slowly/ Wont work unless i plug the AC cord to amp first/////
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119 VAC. 6.53 filament voltage. All tubes are lit up. EUREKA!
Plugged in speaker and RL1 switch is working. Stop!
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Power and Preamp tubes lit up. Have not flipped standby yet.
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He didn't. He only had links 1, 3, 7, and 9 installed when he took those pics. That's the configuration for 230VAC operation.
Yes when he took those pictures but earlier he had a PT that was smoking hot. Could be why?
Brad :dontknow:
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119 VAC. 6.53 filament voltage. All tubes are lit up. EUREKA!
PlugGed in speaker and RL1 switch is working. Stop!
Good stopping point. Now, do the world a favor. If you have a booklet of wire markers label all those transformer wires, ie, W15, W14, W12, etc. If you don't have wire markers then use a good permanent Sharpie and write the W# on the wire connector terminals.
Also, look at the wires for each transformer and tell me what color wire is on each W## terminal. I'll annotate the pdf and post it here. Might prevent some future frustration.
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Yes when he took those pictures but earlier he had a PT that was smoking hot. Could be why?
That's very likely. There's plenty of evidence that he had a jumper across every link at some time, maybe even at the same time. :huh:
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Ok will publish all the wire colors by W numbers. Wow man! You are all King Bee's in my book. I didnt understand the link like i thought i did. Ok posting info in 5 minutes/
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Yes when he took those pictures but earlier he had a PT that was smoking hot
That was when i had a jummper wire across RL1 W7 & W6
Edit:
Thermal Switch Wiring is W3 & W4
Dual (EDIT: (Orange) 10VAC low voltage wires W6 & W7
W10 - White
W11 - Red
W12 - Gray
W13 - Blue
W14 - Black
W15 - Brown
W16 - Purple
W17 - W22
W17 - White
W18 - Red
W19 - Gray
W20 - Blue
W21 - Black
W22 - Brown
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OK, I can stop worrying about that. :laugh:
I knew it would get sorted out.
I've been following the drama for days.
I do hope there are no other issuses, but they will be easier to tackle
if they show up now.
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Wowza! LOUD Monster Is Alive!
640VDC 6550 Plates
270r Screens are 320VDC
-36.3 grid voltage @ 10K grid resistors
Does that screen voltage look right?
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Screen voltage is OK.
I'M STILL WAITING ON THE REST OF THE TRANSFORMER WIRE COLORS!
So far you've only given me 6 wires for each transformer. I know there are 10 wires on the little transformer because I counted them. Don't know how many are on the big one. Give'em to me so I can go to bed.
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Ok im doing it now
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TI-65760C Filament Transformer
W12 & W13 are the (2) short black filament wires going to the power supply board
W6 & W7 are the (2) orange low voltage wires going over to the power supply board
EDITED: 1-8-2014
W17 - White
W18 - Red
W19 - Gray
W20 - Blue
W21 - Black
W22 - Brown
Total of 10 wires on the TI-65760C transformer
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W12 & W13 are the (2) black filament wires going to the power supply board
W6 & W7 are the low voltage wires going over to the power supply board
OK. Now give me the rest of the wires for the big transformer.
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Ok just a min
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TI-65765B Transformer Wires / Total (9) Wires
Thin black wire to PS board W21
Thin Orange wire to PS board W15
Thin Red wire to PS board W16
W10 = White
W11 = Red
W12 = Gray
W13 = Blue
W14 = Black
W15 = Brown
I will do all the OT and some other wire connections tommorrow and Doc the entire amp.
Might as well. Likely wont get another chance at documenting this amplifier
Thankyou millions for your genius and patience!
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I will do all the OT and some other wire connections tommorrow and Doc the entire amp. Might as well. Wont get another chance at doing this
Good idea. Here's the annotated pdf as promised. I'm done.
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Fantastic! I will post the rest to complete the last remaining W connectors.
Long story but i kept looking at the links and wondering WHY? would you have to cut and remove bussed links to change the voltage on an amp. So i kept thinking of a different wiring senario itself. 2 days ago i was thinking should i cut and or add links together to make the changes like you and SILVERGUN were pointing me to. Turns out thats exactly what you all were saying. I think wire swapping would have been a more normal approach when they made the amp.
But seriously this has been fun and painful all at the same time. This is what it's all about and what drives me.
Doug needs to install a Toll Booth for overtime charges. Saving that PDF now. Goodnight until next time*
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Long story but i kept looking at the links and wondering WHY? would you have to cut and remove bussed links to change the voltage on an amp. So i kept thinking of a different wiring senario itself. 2 days ago i was thinking should i cut and or add links together to make the changes
So are you saying that when you got the amp ALL of the likes where in place? Or was it set up for 230v with just those links in place?
Brad :think1:
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So are you saying that when you got the amp ALL of the likes where in place? Or was it set up for 230v with just those links in place?
When i got the amp the pic's i showed of the links were as i received it and it was linked for 230VAC. The later pic's from tonight (now yesterday) show the new links installed and the ones that were removed from the board. Man what a day. I did 4 amps total today. Im wiped out. This one was the real mind bender/
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There's plenty of evidence that he had a jumper across every link at some time...
Gents, I'm 99% sure Plexi didn't put jumpers in all those positions.
Given the way the leads look from the back of the board, they're bent inwards as they would if mechanically placed prior to wave soldering. I think Marshall installs all the links, then clips off the un-needed ones to set the operating voltage for the intended country of distribution.
I'm banking on the links having been set for 230v operation this entire time until he removed all and wired for 115v. And the amp magically worked once that was done, so...
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Yeah HBP thats why i wasnt understanding the link thing. There were several links that had already been cut and the ends bent over. I just didnt get the whole senario of the missing links that appeared to have been there at one time or another. Is this amp the missing link? :laugh: Hell i cant sleep now. But i am very glad and thankful for learning something new and what i may expect in the future with other amps. Edit.
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Wowza! LOUD Monster Is Alive!
:bravo1:
sluckey :director:
I think your "people skills" are getting better :icon_biggrin:
:notworthy:
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I think your "people skills" are getting better
HA! Just wait. I'll mess it up. You don't know how many times I have walked away from the computer in this thread to shake off my frustration.
Plexi50, if there's one thing to take away from this ordeal, it's this... LISTEN TO SILVERGUN!
He tried to steer you to the links early on, even colored them for you. But you didn't understand. It's OK to not understand. Especially when you're up against something you've never seen before. But instead of saying "I don't understand", you assured him the links were right. That sent us on a week long goose chase. And we would still be chasing if you had not finally taken the pics of the links.
So... LISTEN TO SILVERGUN! :wink:
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I should have pulled all the wires off the links from the start instead of peaking and looking through at the links. It may have become more obvious quicker what you all were saying. SILVERGUN you had it right all along. I see wild goose chase's in my future! Ha!
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Plexi50, if there's one thing to take away from this ordeal, it's this... LISTEN TO SILVERGUN!
Whoa, whoa, whoa, whoa, whoa......hold your horses there...
So far I've only proven that I can read a schematic. :icon_biggrin:....and draw pretty pictures
I try to limit my posts to things that I actually know something about :l2:
plexi, there is one other option to consider....
we could convert it to "auto-link" so it senses input voltage and then auto sets the links for you....kinda like this (just a snippet,,,,I don't want to give you "schematic shock")
Now you can see why I could relate to that schematic :huh:
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TI-65760C Filament Transformer
W12 & W13 are the (2) short black filament wires going to the power supply board
W6 & W7 are the (2) orange low voltage wires going over to the power supply board
EDITED: 1-8-2014
W17 - White
W18 - Red
W19 - Gray
W20 - Blue
W21 - Black
W22 - Brown
Total of 10 wires on the TI-65760C transformer
I just edited the W numbers for the TI-65760C filament transformer.
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Now you can see why I could relate to that schematic
Great eyeballs SILVERGUN. You know your stuff pretty good in my book
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I just edited the W numbers for the TI-65760C filament transformer.
Huh? Nothing changed.
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I saw this morning that both transformers has duplicate W numbers.
I Edited reply #114 as well and made a post earlier this morning
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OT Primary Top Row & W Links
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I've been following this thread right along. Plexi, way to stick with it! Sluckey, SG and everyone else who hung in with him, good on yinz! :occasion14: :occasion14:
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Thanks John! Credits go to the guys with more intel than me. Drama was mentioned. Talk about being on the edge! I was up until 1:45 a.m. this morning. It's hard to shut down after a major rush of info and making quick changes. The amp is done and sounds good. I had to retention all the 6550 sockets to keep the bottle pins in there socket. Speaking of sockets and pins these 6550 tubes have very thin pins on them. They are Marshall branded 6550's but i dont know who made them. Probably russia?