Tourmaster 4212 info and problem

[vmangobob]

Hello all. First time poster here after lurking around for a bit.

I have in my possession a Tourmaster 4212 combo amp that belongs to a friend. He bought the amp at a GC somewhere around 2010 or so, he doesn't remember exactly when. It was a floor model but apparently had very little time played on it. My friend played it a short time before he started having physical problems and he put the amp in a closet until now.

The amp does not have a serial number visible on the back, so I'm not sure if it is one of the modded amps or not. Is there another place to look for a serial number?
It does have the PC fan mounted in the back, which surprised me a bit. Not sure if this is part of the modded versions or not.

OK, now to the problem. OD1 is completely dead, no sound at all on any power setting. I asked my friend and he said that the problem popped up toward the end of his playing the amp. All other channels seem to work fine. Reverb works, sounds a little distant but I'm not real familiar with spring reverbs. Have not checked effects loop as I don't use effects.

I have taken off the panel where the fan is mounted to look at the tubes and see if I smell anything burnt. All tubes seem to be glowing and are not microphonic. That is the extent of my troubleshooting knowledge of tube amps, short of swapping out tubes. Upon looking at the tube diagram, I'm not sure which tube or tubes to swap. If od1 and od2 share tubes for most everything, it seems both would have a problem if it is a tube.

My friend let me use the amp to see if I could diagnose the problem and maybe work out a deal to buy. After reading some of the horror stories about transformers I am very apprehensive. First thing will be to see if this channel problem is something major.

Sorry for the large wall of text, I wanted to explain a bit before asking the question.
Any help or information will be appreciated, as I contemplate what to do with this amp.

 

[vmangobob]

A little update. I did go ahead and do some tube swapping to see if the problem followed a tube. I swapped v5 with v6 with no change. I then swapped v2 with v7 and no change. Oh, I also switched channels with both the footswitch and via front panel. No sound from od1 in any scenario.

 

[vmangobob]

Been playing the amp a bit and everything else seems to be fine except for od1.
Talked to my friend again and he said there was a very low volume sound coming from that channel at one point.
I cranked every knob on that channel up and the master all the way up and might have heard a tiny sound. Could have
been my imagination or my will to want it to work. haha

I had asked in the first wall of text but will do again. Is there another place where a serial number is located on this amp?
There is nothing on the back panel. Any help would be appreciated.

 

[Kalle_in_Sweden]

Hi
You can find a link to a tourmaster schematic here:
viewtopic.php?f=26&t=188682
Checking the schematic I found a possible cause for the "silent" OD2 channel.
If the Relay RL5 is not switching as it should , OD2 channel can/will be silent.
Relay RL5 is swithing the signal path from either OD1 Volume and OD2 Volume potentiometers(knobs).
/Kalle

 

[digi2t]

Problems with these amps is pretty well documented. Seeing as how it's a combo, they're prone to a lot of vibration. As such, I would first check the solder joints, especially on the boards carrying all the pots. I've had to reflow all the joints on both boards on mine.

Also, I had a pot ground out on me as well. If this has happened, and it's the channel volume pot, then that will kill the channel output as well.

When these amps are working, they're great. When they don't, they're a bag of cats.