Peavey classic 30 tube amp no sound.

[guysilvermt]

Really 230? Is that standard in UK or you have to run a dedicated outlet? Ok won't turn on but for testing purposes if I want to test outside of cabinet what I. Particular is wrong with how I have it? I was thinking of proping it up between two wood legs so I could put the tubes in?

 

[guysilvermt]

The right cap is way more noticably blown.

 

[guysilvermt]

Damn I just wanted to make some noise not go into tube amp repair mode. I can't afford a professional at this time. Im decent with a soldering iron at least

 

[guysilvermt]

So with my incredibly limited understanding of analog circuits I'd say it's likely that C40 and C39 being blown could reasonably result in no sound at all from this amplifier not even static? Anyone disagree? This is actually the most complicated electrical schematic I have ever put any time into so it is basically nonsense to me though I would like to understand it. Can anyone tell me what the purpose of both these capacitors is, like what makes them a pair? Is it related to polarity?

 

[NoisyIndividual]

C39 and C40 may not be "blown" as such, they may just be leaking and need replacing.
If the fuse has not blown and the diodes are ok, then there may well be something further downstream that is not working.

So C39 and C40 may be a problem, but not the one that made a burny smell and broke the amp.

 

[guysilvermt]

Dang that's what I was worried about! It is a possibility, though I think unlikely that a metal clip that works as a thread for the bolts that holds in the board created a short that caused the damage. I noticed it was loose when I opened it up, but it wasn't anywhere near the blown caps and was close to where it came from. No fuses are blown the diodes all tested out nothing else appears burnt or is visibly damaged. The smell was not the smell I associate with a shorted circuit, in fact it didn't really smell at all just smoked a bit

 

[Barry Farmer]

I'd change C39 and 40, check the fuse - it SHOULD have blown! Lots of Volts around there - BE CAREFUL!!

 

[BIASKING]

All the electrolytic caps should be replaced. Especially all the Gray Illinois brand.
One other thing to check are the tubes. If you'll notice, the heaters are in series, so if one opens the entire path is open.
Like the old Christmas tree lights.
Also don't bend the "taco" back and forth more than once or twice or you'll be replacing all those solid jumpers. Ask me how I know...

 

[guysilvermt]

Theese are great sounding amps but the folded PCB construction is a bit of a nightmare.

Just one caveat - I think the mains transformer has a non resettable thermal fuse buried in it? Not 100% sure.
So don't be tempted to run it until you have replace both of those capacitors, rather than just snip the bad one out.

I've changed a few of these transformers, fortunately I think TAD make a replacement.

All fuses are good. Could this be the issue?

 

[NoisyIndividual]

Unplug the amp from the wall and measure between Live and Neutral or whatever you call them with the mains switch on. You should be able to read some tens of ohms of the transformer primary. The thermal fuse, if it has one, will be in series with the primary.

 

[pucho812]

All the electrolytic caps should be replaced. Especially all the Gray Illinois brand.
One other thing to check are the tubes. If you'll notice, the heaters are in series, so if one opens the entire path is open.
Like the old Christmas tree lights.
Also don't bend the "taco" back and forth more than once or twice or you'll be replacing all those solid jumpers. Ask me how I know...

I would ask how you know but I know that too

 

[BIASKING]

I would ask how you know but I know that too

I now know that you know I know... ;-)

 

[guysilvermt]

From reading others description of this amp I wonder if mine hasn't been modded by a previous owner? Others have described the clean channel as its best feature and some called it" overly bright" and the boost as " not very useable" and the bass to be "muddy". Nothing like my experience, I would say their isn't any clean channel, as it sounds a little overdriven on every setting, Bright and clean are the last words I would use to describe. I have called it crunchy, deep, aggressive and would say it always is. I think the boost button is very useable, though I would dial back mids when I did, but after cleaning tube sockets I thought I observed a dramatic decrease in its effect for the 10 minutes I had to play it. Im bummed cause I had been dealing with cracking and popping the for awhile and all it needed was a simple pot and socket cleaning and was working like new then this happened.

 

[guysilvermt]

Yeah I was really hoping this could just be an easy repair without having to know myself!

 

[guysilvermt]

The filament on the 1 amp main fuse and on F2 is thin as a hair I don't understand how it couldn't have blown a fuse and why it isn't making any noise at all?

 

[guysilvermt]

Unplug the amp from the wall and measure between Live and Neutral or whatever you call them with the mains switch on. You should be able to read some tens of ohms of the transformer primary. The thermal fuse, if it has one, will be in series with the primary.

Ok I'll give him this a shot.

 

[guysilvermt]

This is someone else's pic but apparently your memory is correct.

 

[guysilvermt]

With multimeter on ohms 200 setting from primary to secondary reading is immediately around 32 and then right to 6 and down slowly from there? So this is very small resistance and possibly the issue, if I am interpreting this correctly?

 

[Mihobro]

Start by pulling all the tubes and checking all the power supplies. Because of the smoke, If they OK check out at the sockets too. It they are off then check bias resistors. then check for bad tubes, especially open circuit on the filament heater coil. (looks like some are AC,) If they check OK, then put in the preamp tubes and test the audio in to the insert out to check the preamp stages. If the preamps check OK then it is a problem in the power amp, Check the bias resistors 40 thru 55. Replace as needed. a burned bias resistor could be a sign of a shorted tube. So be prepared to replace output tubes as needed. The stage before the power tube, the dual triode, is called the splitter and divided the signal into two with one being the invert of the other, The power stage has two pairs of tubes. Be suspicious of the associated tube of a burned or open resistor. the tube could be shorted. If it all manages to power up without any smoking. If there is still no output it could be the output transformer. or the speaker, did I say to check that first? There are a few switches and relays in there. so all the loops and reverb send and return as well as feedback? could also cause the amp to. not pass signal.

from a guy with a Fender Tech Certificate (they were giving them away)

 

[Mihobro]

Picture posted after I wrote. Caps show no sign of leaking, goo is just to hold them in place and limit any microphonics. Picture with transformer has a little heat protect device, this will go open (high resistance) if head exceeds it's threashold. The usually recommended fix is to replace the whole transformer assy. but it looks like you could replace it. Just make sure to adequately insulate it as it is 120VAC.
The little caps are to filter out RF and other high fequency interference including the harmonics(buzzing) of the 60/50 Hz supply.