Amp smoking. Help!

[JP2036]

That amp with no ground & 240 volts is a DEATH TRAP Bro.
You could be the next thing smoking.

 

[neikeel]

@Filipe Rolim
Well part of what I'm wondering is if there is a voltage selector on the back of the amp, or if the different voltage taps are selected by changing wire on the transformer? A pic of the rear panel and possibly a "gut shot" may be helpful.
Thanks,
Gene

Gene! You read the thread-he is in Portugal!!
The PT actually smokes - never going to survive that - sorry.
The amp is stock PA so well worth getting up and running again

 

[neikeel]

The amp came from U.K. ??
Brown straight to on/off is live (should go into fuse holder first).
Blue is neutral and should be connected to orange (common) but typically via selector and then the other (missing) pole of the on/off switch.
Some things to correct whilst you get a new PT!

 

[Guitar-Rocker]

I agree a replacement PT is needed, or have the original rewound. It does sound like there are a few wiring issues to correct though, as Neikeel advised, but a few more pictures may reveal if anything else may need corrected. As Gene asked can you take a few more pictures, especially around the power tube sockets and in the bias circuit area? While you are fixing issues , you may or may not need to replace screen resistors or power tube sockets also.

 

[neikeel]

I agree a replacement PT is needed, or have the original rewound. It does sound like there are a few wiring issues to correct though, as Neikeel advised, but a few more pictures may reveal if anything else may need corrected. As Gene asked can you take a few more pictures, especially around the power tube sockets and in the bias circuit area? While you are fixing issues , you may or may not need to replace screen resistors or power tube sockets also.

Agreed although these have pretty high quality ceramic octals and failure/arc over is very rare but the screen resistors will need a check over.
Last one of these came may way was mugged for its iron/pots/selectors and hardware and found its way into a Valvestorm chassis and became an SIR type amp as it still had the turret board (confession over!)

 

[Filipe Rolim]

The amp came from U.K. ??
Brown straight to on/off is live (should go into fuse holder first).
Blue is neutral and should be connected to orange (common) but typically via selector and then the other (missing) pole of the on/off switch.
Some things to correct whilst you get a new PT!

I bought it here in Portugal, so I don't know if the cable cord was switched( most likely not, if so, only the plug would be switched out)
For the owner it was just somwyhing collecting dust in the attic, he tried to turn in on when we meet but I stopped him from doing it as it had no load but I don't know if had done it before(most likely yes)
That replaced switch looks like something that someone had laying around in a toolbox and would do the job....as you can see the end result. Just a similar to the stock one btw

 

[Filipe Rolim]

I agree a replacement PT is needed, or have the original rewound. It does sound like there are a few wiring issues to correct though, as Neikeel advised, but a few more pictures may reveal if anything else may need corrected. As Gene asked can you take a few more pictures, especially around the power tube sockets and in the bias circuit area? While you are fixing issues , you may or may not need to replace screen resistors or power tubes sock

I agree a replacement PT is needed, or have the original rewound. It does sound like there are a few wiring issues to correct though, as Neikeel advised, but a few more pictures may reveal if anything else may need corrected. As Gene asked can you take a few more pictures, especially around the power tube sockets and in the bias circuit area? While you are fixing issues , you may or may not need to replace screen resistors or power tube sockets also.

here are a few more

Notice these 2 outputs coming from the second channel

 

[Filipe Rolim]

and the full view

 

[danfrank]

Here's the video for it

And now that room smells like $hit...
Lol!

 

[Matthews Guitars]

It's rare to actually capture the death of a transformer on video.

That one's done. Well done, actually.

 

[Filipe Rolim]

It's rare to actually capture the death of a transformer on video.

That one's done. Well done, actually.

I might sell the video as an NFT "rare footage of an amp dying" or make a true crime doc about it! Ahah

 

[Joe6BG6GA]

Hey there. I'm looking for some advices to this.
I got my hands on a Marshall Master Pa 100 Head from 1974.
Looks old, not really well trated.
Tried it out and the PT started smoking.
Changed the tubes. Put a new fuse in( there was a 2amp fuse where it should have been a 1amp fuse).
Fire it up again and it started smoking again. The thig is. There are no burnt components, loud pops, volume loss. Nothing. It sounds sweet, but again, there's that smoke.

Greetings! Pull out all tubes; if PT still smokes..it has shorted primary winding.. Time to replace

 

[Filipe Rolim]

Greetings! Pull out all tubes; if PT still smokes..it has shorted primary winding.. Time to replace

hey mate
thanks for the tip.
power and pre tubes?

cheers

 

[David Copeland]

First of all the smoke looks to be coming from the under side of the amp not the P.T. in the video. My second point is with all the apparent strange wiring in the amp my advice is to do no more tinkering but get it to a qualified tech for analysis. Taking this route will be cheaper in the long run and may in all probability prevent more damage and possible personal injury.

 

[Justin Whitstine]

smoooooooooooooke on the watttttttttttter
and fire in my amp

 

[Filipe Rolim]

First of all the smoke looks to be coming from the under side of the amp not the P.T. in the video. My second point is with all the apparent strange wiring in the amp my advice is to do no more tinkering but get it to a qualified tech for analysis. Taking this route will be cheaper in the long run and may in all probability prevent more damage and possible personal injury.

Smoke was coming from the bottom wire exit on the transformer. the incorrect wiring is solved now. installed a 4 lug switch like the original one. also the two extra outputs coming from send and return seem to be in series with the first channel

 

[JP2036]

First of all the smoke looks to be coming from the under side of the amp not the P.T. in the video. My second point is with all the apparent strange wiring in the amp my advice is to do no more tinkering but get it to a qualified tech for analysis. Taking this route will be cheaper in the long run and may in all probability prevent more damage and possible personal injury.

We carry the message but not responsible for outcomes.
Some people believe the internet can fix anything.

 

[JP2036]

Smoke was coming from the bottom wire exit on the transformer. the incorrect wiring is solved now. installed a 4 lug switch like the original one. also the two extra outputs coming from send and return seem to be in series with the first channel

Oh cool no worries.
Should be like brand new now.

 

[Filipe Rolim]

Oh cool no worries.
Should be like brand new now.

Chill out JP. not getting you motivation here....
The amp is now a friend who's an electrotechnical engineer and a musician also, so you can sit and calm down.
if there are things I can solve in the amp by myself, why not? not saying by fixing those isues I brought it back to life.
or if you were in the same situation, you wouldn't solder two wires to a switch and check a problem out of the list?
You probably know much more about these things than I do but if that's your idea of helping.... seems a bit off.

 

[fitz]

Chill out JP. not getting you motivation here....
The amp is now a friend who's an electrotechnical engineer and a musician also, so you can sit and calm down.
if there are things I can solve in the amp by myself, why not? not saying by fixing those isues I brought it back to life.
or if you were in the same situation, you wouldn't solder two wires to a switch and check a problem out of the list?
You probably know much more about these things than I do but if that's your idea of helping.... seems a bit off.

The people who know more than you have offered assistance as best they could.
People who don't know what they are doing just post things to humor themselves.
What's the word for that....?
Urban Dictionary: forum troll