Tourmaster 4212 Pots Keep Shorting Out

[musitron]

Hello Rig-Talk; glad to have found your little corner of the internet.

I have a Tourmaster 4212 that has to be repaired, AGAIN. I love the sound of this amp, when it works.... trouble is, it often doesn't.

The problem I'm having is potentiometers keep shorting out, and it isn't just one (though a couple of times it's been the bass pot on Ch1.) These are Alpha pots, but it looks like some were squeezed or something during manufacture or build and the wipers keep touching the case, causing a short and taking out whatever EQ band that pot is assigned to. The offending pots have been rebuilt a couple of times and this keeps happening to different ones, and now I think it happened to the volume pot on Ch3 because the whole channel is dead. The amp isn't even in heavy use; maybe once every week or two in my studio. It hardly ever gets moved around, and sits in a 65 degree room all the time.

No more... I just want to replace all the damn pots in the thing with new ones and be done with it. Trouble is, some pots don't have readable identifiers on them..... anyone know where I could get a schematic or at least a list of the pots and their values?

Also, has this happened to anyone else here?

Thanks for reading,

J

P.S. I don't have a warranty.... let's just say I'm "hands-on."

 

[Anonymous]

you can meter the pots to get readings. set your DMM to read 1000k or 1M on the resistance setting. you'll have to desolder them from the board to do so, as they probably wont give accurate readings while on the board/in the circuit. it may just be worth having it repotted than to delve into that project

i dont know of any place on the web that has a TM schematic. i've been looking for one for 3 years now. there's a lot going on in that amp, thats for sure.

for the inexperienced, it looks to be a major underaking to take this amp all apart and meter those pots off the board, but could be done if you take pictures of what wires go where and make some diagrams. i installed my own replacement power tranny in my TM without incident. i've also installed a replacement reverb tranny in my amp too (and need a new one). i'd say there's been some QC issues with the components, for sure...still, like you said, a great sounding and versatile amp.

 

[Soundboy619]

Hello rig-talk,

If anyone does map out the pots/values. Can you please post them for other Tourmaster owners?

I’m currently trying to sort out all the bad crap in my Tourmaster (new power transformers, caps etc).

Like everyone says, they sound great when they’re working… just trying to make mine a bit more reliable. It really is my favorite amp of the ones I own, something about the perfect tone makes you play better and you tend to chase that tone for that reason.

I did find a few of the early schematics on the web, good for cap/resistor values… no pots unfortunately.