Help! I built a 5f2A and I have no sound... Newb.

[silat]

I built a 5f2A in a Russian ammo can and I have no sound . If I give pics can someone help me to get this thing going? When you see the pics you will know I have no technical knowledge but I am doing this to try to learn. Everybody has to start somewhere right? I built One other amp but I was just a monkey following pictures for the banana prize ( 5e3 tweed deluxe). Please walk through this if you would and  talk to me as someone with no knowledge. I will have to give pics upon request or find another way to do it.

I would appreciate any and all help in and all help.

Thank you!

[silat]

As you can see it is sloppy but I hope to get better.

[silat]

Here are some more. I did hook it up to a speaker and made sure there was a load on it I also checked it with a load limiter light and found out I had the preamp tube wired up wrong and had to change it.

[Willabe]

Hi and welcome silat!

Well (and I say this with respect to you to help and not to be harsh) it's hard to see with the way the wires are flying in the air with extra length also on some/many of them.

From what I see, you need to work on 2 things to start with;

1. Your lead dress. Lead dress is how you run your wires in the chassis. Some/many of the wires going from the eyelet board to the tube sockets usually are 'dressed'/laid down to the chassis. You want some extra wire so their not tight but not too much extra. Sensitive grid wires need to be away from heater and higher current/voltage signal wires so they don't amplify their noise or introduce parasitic oscillation.

2. You need to work on your soldering skills.

Everybody comes to the table at 1st the same, with little or no skills and understanding of these things. We ALL learn these things as we go.

Here's a few links to look at from Slucky's web site to see some Great examples of excellent lead dress and soldering joints.   

Study their work it will help you get a place to start at.

http://home.comcast.net/~seluckey/amps/VAC15/ac15.htm

http://home.comcast.net/~seluckey/amps/revibe/revibe.htm

http://home.comcast.net/~seluckey/amps/warbler/warbler.htm

Here's a couple links of our host Doug's work, excellent as well.

http://el34world.com/Hoffman/images/IN-54.jpg

http://el34world.com/projects/ReVibeRack1.htm

There are many more great examples here all over this forum, these 2 guys work was just easy for me to find.


                   Brad        

[eleventeen]

You get nothing, zero, out of the output jack? No hum, no tube noise, even with no instrument plugged in?


The tubes light up?


Do you have any sort of meter to measure voltages?


Have you taken a schematic and with colored pencil, made sure you have each and every connection made, one-by-one? And....IF you have a meter, made sure that your eyes weren't fooling you by testing each and every connection with your ohmmeter or better, your "beep" continuity function?




You're not giving us much to go on.

[silat]

Thank you to both Brad and eleventeen for taking the time to answer my post and being honest. Hit me with everything you got... I am not a baby and the lessons are hard to learned sometimes. All the tubes light up.I do have a meter. I burnt my first one up checking voltages so i a little apprehensive. I had some really high voltages in the 700 range and then found out my preamp was wired wrong I had them moved one pin wrong on every pin. and that seemed to bring voltages down to the 500's. Another thing that has me stumped is it seems like my capacitors are draining on their own. I still trying to learn  about the schematics symbols. I went over to uncle dougs youtube videos and they help but I have a lot to learn.

[silat]

You know, I actually had this thing looking a lot better than the pictures show when I first did it..My wife even commented that I did a really neat job; but after changing all the wrong wires and mind you I do have some really extra long wires,  after it does not work and you keep changing stuff I stopped caring about my dress. But that is no excuse.

[eleventeen]

Something is really flaming (no pun intended, but not entirely kidding) wrong if you have 700 freeking volts. That's a solid double of what you should be seeing in any sort of Champ. If you fed your 350 volt caps 700 volts, they are virtually certain to be fried---and thus they might very well drain on their own---because they are shorted out cooked on the inside! Surprised that didn't blow your fuse with extreme prejudice. (which leads to the question---why didn't it?)


Lead dress is important when it comes to chasing hum out of a build (or never having it in the first place) but obviously no amount of nicely routed wire is gonna fix incorrectly hooked-up wires/parts. 


In very general terms, what we would want you to do is to:


1: Very with near metaphysical accuracy that every wire is connected to the right place before applying power.
2: Build and plug the thing into a "light-bulb limiter" (search the forum) for first turn-on test---but it seems like you are past that.
3: With the 5Y3 removed, verify that the other tubes light up.
4: With the 5Y3 installed and your meter clipped on to either pin 2 or pin 8 of the 5Y3, see that you get no more than about 350 volts DC.


And even more generally...are you sure you are counting & identifying the tube pins right? As viewed from the underside, clockwise from the gap on the 9-pin and clockwise from the key on the octals. (If you get to ask irritating questions, we do too  )



c

[Willabe]

Link to Slucky's web page with the light bulb limiter;

http://home.comcast.net/~seluckey/amps/misc/Amp_Scrapbook.pdf


                Brad     

[silat]

I built a light bulb limiter from sluckey's page already and have used it. It is what alerted me to the fact  that I had the pre amp wired one over wrong. I plug it now I get no light on the limiter unless I touch something wrong with  my meter pobe.... With the 5Y3 removed both the 6V6 and the preamp tube light up. With my meter I have nothing on pin 8. I have 2.4 volts ac on pin 2.  I tried to make sure I traced down the numbering correct on the other pins. They should be correct. 

[eleventeen]

"With the 5Y3 removed both the 6V6 and the preamp tube light up. With my meter I have nothing on pin 8. I have 2.4 volts ac on pin 2."


Taking out the 5Y3 disables any sort of rectification = the making of DC within the amp. We do this so that in the initial stages of checkout we are not applying what SHOULD be 320 volts or so (DC!) to things that may be miswired, but we can see if the other tubes light up. So this is a "freebie". That's the thinking. Other than the 120 VAC we are at that point applying to the power transformer, we are not powering "anything" in the amp more than the "tiny" 6.3 volts needed to light up the non-rectifier tubes....AND the 5 volts AC the 5Y3 >>SOCKET<< (with no tube installed in it) 5 volts AC, to pins 2 and 8. AND: big AC volts to the 5Y3 plates, pins 4 & 6. But with no tube installed, those Big AC volts go nowhere. Still...you should confirm they go to pins 4 & 6; visually, and at your stage of learning, probably with your meter as well.


So it is blessedly normal for you to see ~~2.5 volts AC on your 5Y3 socket


>>IF and only if there is a 5 volt center tap---which I kind of doubt unless you say there is one<< so that is yet another mystery.


But: It's entirely non-normal for whatever you see on pin 2 to >>NOT<< be on pin 8 of the 5Y3.


If you find 2.5 volts AC on pin 2 of the 5Y3 socket, why are you not seeing EXACTLY the same 2.5 volts AC on pin 8? You should.


Do you have a CT on your 5 volt winding? That's somewhat unusual on little power trannies; not impossible, but rare. 

[silat]

No. Here is a copy of the PT and it shows 5 volts 4 amps.

[Willabe]

Lead dress is important when it comes to chasing hum out of a build (or never having it in the first place) but obviously no amount of nicely routed wire is gonna fix incorrectly hooked-up wires/parts.

Yes (and again I say this with respect to our new member) but I couldn't see where the wires were coming from or going too. I was hopping to maybe see something that was wired incorrectly.


               Brad     

[John]

Looking at the schem, it does show a CT on the rect. winding.


Here's what I'd if it was me. Pull the tube like 11teen said.  Disconnect the wire from pin 8 on your 5y3 socket that goes to your output tranny. (By now you're getting good at de-soldering!) Measure your ac voltage, going from pin 4 to ground, and pin 6 to ground, making sure you have your meter set on AC. Then measure the voltage *across* pins 2&8. Across 2&8 it should be about 5 volts a.c. I'm wondering about that CT, whether it's giving you  higher voltages, although the schem says it's to be there. Anyway, 11teen's right, no way should you be getting 500 volts DC at pin 8 with your rect. tube in. Naturally, make sure you've got the yellow wires on 2&8, and the red wires on 4&6, and the red/yellow stripe wire going to ground.


Trouble shooting is my weakness, I'll be the first to admit, so when building anything, I install the PT, measure voltages, install the OT, measure voltage, etc. Otherwise I spend hours catching what I did wrong if I wait till it's all built. Good luck, you'll find the problem!

[John]

Hey, just looked again. That red/yellow stripe wire. That's probably your CT. Is that connected to chassis ground, or just to the terminal on that tag strip?

[John]

Just looked at your PT file from Mojo. IF I'm reading it right, with your CT grounded, it sure is possible you could be getting 700 rectified volts. With it not grounded, you're still looking at roughly 462 (330*1.4) unloaded. I'm sorry, I forget exactly the way PRR explained it, but with a 330-0-330 PT, which you apparently have, if the CT is grounded you have much higher voltage. Anyway, throwing things out there as I think of them, hopefully they help a little.


Of course, none of that explains why you have no sound.  I'm betting on a signal wire that's grounded out, or something like that. Miswired pot maybe. Many things can happen during a build.

[silat]

Hello John! The red /yellow is connected to the tag strip it is  not grounded.

Thank you for getting in on this.

[eleventeen]

Whoa. The CT is on the >>HV<< winding, not the 5 volt winding. And it (the HVCT) needs to be there. And it needs to be grounded.


Still unanswered is the question of how you can get 2.5 volts on one end of the heater winding. One answer: You are powering the tranny's 240 volt primary from your 120 volt line. No good.



There is no way to get 700 volts DC out of that transformer without a voltage doubler or a birdge rectifier, either would have to be built on purpose, with silicon diodes, so it's safe to say that isn't there. I don't see a way you could accidentally get 700 VDC from that tranny. So, now we have to consider measurement error. 


With a 5Y3 grounded-center-tap rectified lashed up to a 330-0-330 tranny, you should get 1.4 * 330 (or if you prefer, .7 * 660) less the drop across the 5Y3, maybe 40-60 volts. So the filtered, no-load DC should be about 410 volts +/-. 

[eleventeen]

The R / Y center tap >>MUST MUST MUST<< connect to ground, the rectifier has no return without it. That's a magnificent explanation of why you have no sound.


But when you connect that R/Y to ground, you will be playing with the big boys, meaning, you'll be supplying the circuit with B+ in the neighborhood of 400 volts. Be sure your wiring is right! So get the lightbulb limiter and if you've put a 15 amp fuse in the fuseholder "just to test things out...."....get a MUCH lower value fuse on there, probably 1 amp.

[John]

There is no way to get 700 volts DC out of that transformer without a voltage doubler or a birdge rectifier, either would have to be built on purpose,

I got it backwards, thanks!

[silat]

Ok Thank you all much. I did what you said. I grounded the Y/Red and my lightbulb Limiter takes a good while to light up but it lights  a faint glow after about 45 seconds maybe longer but  I still have no sound . I have not checked the voltages but I have not blown the fuse.

[HotBluePlates]

Ok Thank you all much. I did what you said. I grounded the Y/Red and my lightbulb Limiter takes a good while to light up but it lights  a faint glow after about 45 seconds maybe longer but  I still have no sound . I have not checked the voltages but I have not blown the fuse.

Cool. Now measure voltages on all tube pins and post.

[silat]

5y3 pin 4 -276  pin 6-276 pin 2 -696 pin 4- 696

6V6 pin 2-2.4 pin my voltages are to high and burnt my meter up I had it VAC.

[Willabe]

pin 2 -696 pin 4- 696

That's WAY too high, somethings very wrong.   

Are you sure you have the PT's primary wired up right? Only 2 wires should be hooked up. If in the US should be the Black and the White for 117/120vac from the wall.

my voltages are to high and burnt my meter up I had it VAC.

Maybe, maybe not. A lot of meters actually have an internal fuse, if yours does you might get lucky.


                    Brad     

[silat]

I now have permanent black dot in the middle of my meter. I just do not understand how and why they are that high.

Yeah I have the black from the pt going to the fuse and the white from plug going to the back of the fuse I have the white from the Pt going to the power switch  and the Black from the plug going to the other Lug of the switch. The green is grounded.
My Meter does have internal fuses.

[silat]

The meter is a Craftsmen tools I just purchased so I think I can get another if Sears still holds the great guarantee they have on their tools. To all you Limeys out there they are big retail store that is pretty good on tools. But I do need to find what the problem is as I will destroy all of my meters. I thought I was crazy and reading my meter wrong but it cannot be because I am destroying meters on the VAC setting.

[PRR]

> no way to get 700 volts DC out of that transformer without a voltage doubler or a birdge rectifier

Ground one *end* of the 330V-0V-330V, hang one diode on the other *end*, you get half-wave at over 600V.

This implies *multiple* wiring mistakes.

There is also the possibility (some parts of the world) of a 120V primary on a 240V wall outlet.

> Verify with near metaphysical accuracy that every wire is connected to the right place before applying power.

+1. No fooling-- wrong connections can be BIG trouble.

Double voltage is FOUR times the power to EVERYTHING in there, so a lot of possible damage.

[eleventeen]

It wasn't clear to me that you might be in a 220/240 volt country where you are building this. I just assumed you were 120, sorry.


You really, really have to be careful you aren't powering a 120/240 volt transformer with 220/240 volts. Your HV will produce very high volts should that be the case. You *might* have burned out the heaters on your tubes if you fed them double-voltage, but who knows. You *could* potentially cause an arc-over on the HV secondary because it's meant for 660 volts, not 1320. Things start to get a little sparky over 1 kv, and transformer startup surge would be a wonderful time for such arcing to occur. Now you have a carbonized path established inside the tranny, perhaps an insulation failure, and you are done. Unfixable, pretty much. 


The SECOND best way to do this is to refer to the mfr schematic and use his color code. Why only second best? Because one in 10,000 transformers just might have the wrong color wires relative to how they are called out on the part dwg. Yes, astronomically rare, but it happens. The BEST way is to power up the tranny and measure the HEATER volts using alligator clips to keep your meter leads connected to the wires under test, keeping any other wires taped up or otherwise insulated and away from the action. That way you are dealing with either 6.3 volts or 5 volts (AC, of course) and not what could be meter-blowing volts on your HV. Is this silly? 10 seconds versus blowing up your meter? Or blowing out your tube heaters, even turning the thing on for a preliminary test part-way through a build?


I have never seen it as an absolute rule, but I would bet that 99% of tube amp builders will turn on a partially completed build when the heaters are wired (they are most often wired first because they are either UNDER other wires, or, in the case of a Fender, "up in the air". Most builders will wire up their heaters first, and when done, they power up the build and minimally, confirm the tube at the farthest end of the string lights up.


If you're powering a 120/240 volt transformer from 120 VAC, it's not quite as big a deal. You can't get double-volts out of it. On 240 volts, you have to be double, triple careful. You make these kinds of tests at the beginning because it removes any need of having to think or worry about it later.

[silat]

I am in the US and i was  pretty sure I was only looking at 120 VAC. My house is a little old maybe the early 80's.

Thanks to all of you who responded. I am waiting on my other meter now and I will confirm I have everything wired correctly which I thought I did before but obviously did not. I now know I need to be more meticulous in tracing it out.

[silat]

It's alive! It sounds like hammered goat crap. I think I had a death cap wired to my PT on the fuse acting like a doubler. Now i have taken that off it works but all the way up it is faint and distorted very bad. Voltages are still to high so that is not the problem. At least I have sound now. I still have to trace the problem.

[silat]

It is clean and loud now. No hums or noises. I had my speaker jack wired wrong.I have no tone control interaction whatsoever.

[Willabe]

Hey, that's great!   

Tone control sounds like it's a wiring error, you'll find it.

But what is the B+ now?


                 Brad     

[Platefire]

You've apparently got it wired wrong. If you not familiar with reading schematics, you probably can follow the
5F2A layout better. The 5F2A tweed tone stack in kinda like sticking a 500pf silver mica bright cap between the input and output terms of your volume for a treble boost---only difference is the amount of signal treble boosted  through the 500pf is controlled by a 1 meg pot which is fed back to your volume pot output term that then goes to your second stage of the 12AX7 and then to power tube. Of course you also got the .0047 cap to tone pot ground term to chassis ground that's part of your tone control. So the 5F2a tone stack/pot is just a controlled treble cap jumper between you input and output terms of the volume. For me it's easier to think of it that way---may help you too. Get it wired right and it will work fine. Platefire

[silat]

5y3 268 pin4, 268 pin6, pin 2+4 3.9

[Willabe]

5y3 268 pin4, 268 pin6, pin 2+4 3.9

I think you mean pin 2+8? Should be ~5vac.

But what is pin 8 VDC? That's your rectified and filtered B+.

   
                         Brad     
 

[silat]

Yeah sorry you are right 2+8. Pin 8 is 314

[eleventeen]

"Pin 8 is 314"


Right on the money.

[silat]

Thanks to everyone who helped. I appreciate very much! Now I need to work the bugs out. I am tone freak and i am not happy with the no tone interaction. what does it take to really tweek some freaky tone?

[eleventeen]

Well first, get it working "normal" "right". It's pretty tough to not have that particular tone arrangement work. You kind of have one wire in and one wire out.


If your VOLUME control works but the TONE does not, it can be nothing else than the tone pot and the caps that "surround" or "flank" it---in schematic terms. More likely the .005 cap on the left isn't making a good ground connection. Maybe, if you have made the ground connections on the caps to the cans of the controls, you've made bad connections there and the ground connections that are needed to make the tone control work aren't happening. That would be my guess. But that control, those 2 caps, that's where your problem resides, guess or no guess.


 


You can either try to remake those connections on the cans of the pots, [best] or, if your soldering iron doesn't have the oomph needed to make good connections (which is why those connections may not be so good in the first place)  run those supposed-to-be grounds over to the ground terminal on your input jack. The negative of the electrolytic caps probably seems more physically convenient but my suggestion would be "don't go there". Possible hum issue.


*IF* you are going to rely upon the cans of the controls for your grounds---those are REAL circuit connections...they have to be sound. Depending upon how muscular your soldering iron is, you may have to heat up the can a lot. Before doing so, it's generally advisable if not required to file off a pea-sized area of shiny metal to make your solder connection on. You have to be sure you are making a good solder connection there---it has to have filletted-out edges, washed-out edges, it cannot be a "blob". Blobs are NG, those are not valid solder connections.


Anyway...where you connect the .005 to the pot can on the tone control, you may have to apply heat to the thing more (eg; for a longer period of time) than would be healthy to apply to the .005 cap.  Solution: Make that properly flowed solder connection to the pot can WITHOUT the .005 involved, then, reheat and get the lead of the .005 in there.

[silat]

Thank you eleventeen! Yes I understand about soldering because I am plumber by trade. A soldering iron is little different than my torch. I am not much of an electrician though. I do think the connection to the pot might be the problem though.

[eleventeen]

It's *also* possible that if you tried to make the .005 uf-to-can connection and had to heat it too long you cooked that cap.


In electronics, many many times we "tin" the parts we wish to bring together in a solder connection---the bigger the eventual connection, the more we may want to do this. If you do plumbing, you can't do this because your typical 1/2" or 3/4" copper pipe will no longer fit into a "T" or an elbow once it is tinned. Yes, you can fit already-solder-coated pipe into a fitting but only if you reheat both of them---and that is awkward without a good way to hold the fitting under heat. With copper pipe, you clean the daylights out of it, coat with flux, and make the whole connection at the same time, for the most part. One shot. That of course doesn't apply if we are bringing a few wires into a terminal lug. There we can tin and still get the wires through the lug. Once that's done, when we finally *do* make the "all-in" connection, the flux inside the solder doesn't have to do any deoxidizing work (it still has a mild wetting function) and all we have to do is to get the solder to flow. The net result is if we're making a connection with 4-5 wires going to it, we are heating the joint less, it's more likely to "take", and the joint looks better because the wire insulation melts or shrinks back less.

[PRR]

Also Plumber's Flux is much more aggressive than Rosin.

Possession of "acid" flux around a computer factory (back when computers were hand-soldered) was grounds for instant dismissal. The joints work today, and maybe to the customer's place, and then the fine wires rot-through. This is very costly for everybody, bad attitudes all around. Even a suspicion a guy might have used acid flux would get him pink-slipped, him and his toolbox escorted to the gate. Not such a problem with the thick pipes (even tubing) used for plumbing.

[silat]

I can admit that when I first started soldering electric components in amps I was wondering about flux to clean the connections.  I soon learned it did not need it and the solder would flow just fine with plenty of heat or capillary action to the two points being joined. Tinning before helps to ensure no problems.

[eleventeen]

But PRR makes a very important point...acid flux as used in plumbing is a most serious no-no in electronics---just in case you were pondering it. The correct takeaway from plumbing is that for electronic soldering, if something you wish to include in a solder joint isn't already tinned  (most R and C leads are) if it's not bright and shiny it can STILL be oxidized enough to cause trouble from excess finger-handling or being 20+ years old. If you happen to go in a direction that includes using older parts, salvaged or surplus, occasionally they can be maddening to make good connections to. *Never* hurts to pre-tin just about anything.

[silat]

No I was not pondering it. when I first started which was a year ago I was thinking that was what I needed until I looked further into it. I really need to be careful with what i say here. things can be misunderstood real easy.

I mean no disrespect either.

Thank you!

[PRR]

"For electronics solder" normally has rosin flux built in, "flux core".

Fresh parts usually solder-up with the flux-core.

Older parts often need some tarnish removal. Pocket-knife is traditional. Also sandpaper. Fine wire-brush can be useful, though like your BBQ grille you need to get all the stray brush-wires off afterward.