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I bought an old (72ish) traynor ygm-3, and after a good amount of time troubleshooting suspect components, I found the culprit in a loose wire. Re-soldered that, and the amp is now bordering on fully functional.

My problem is this: the tremolo only works on really high settings- ie. level has to be past 2 oclock, and the speed has to be above noon. At that point, it is still subtle. Cranked further it becomes quite apparent, but by that point it sounds like a ring mod.

Is it maybe a tube problem? I am going to grab a new 12ax7 and try that.

Maybe bad pots?

any suggestions are welcome.


2ndly: the reverb adds a fair bit of hum. I'm thinking of putting it in a head box anyway, so would it help to shorten the reverb send/ return cables?

thanks
 

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The quickest way to fix the trem is replace the 3 oscillator caps. The schematic I glanced at showed 0.01 (2 of them) and a 0.015 uF.
Replace all 3 and I'll bet you'll be back in business right away.
 

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I'm thinking of putting it in a head box anyway, so would it help to shorten the reverb send/ return cables?
Isn't it easy to run into problems with increased noise/hum if you you put the reverb tank too close to the chassis?


I don't know why, I just read this on a forum. Hope someone will explain it in (easy) electronic terms.

Dave
 

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Isn't it easy to run into problems with increased noise/hum if you you put the reverb tank too close to the chassis?


I don't know why, I just read this on a forum. Hope someone will explain it in (easy) electronic terms.

Dave
It can, but it doesn't have to. What you must watch out for is the output end of the tank being close to the magnetic field of the power transformer, inducing hum. Usually the metal of the tank provides enough shielding but it can happen.

Shortening cables doesn't usually do much 'cuz they're shielded and that means they're not SUPPOSED to pick up hum! More likely it's a tube or a component failure inside the amp. Most reverb circuits from that era seem to pick up some hum no matter what you do but it should never be noticeable or a PITA unless you're really cranking the reverb knob well past 6 or 7.

There can also be a broken wire inside the spring tank that can cause hum.

Keep looking! It's worth it!

:food-smiley-004:
 

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The quickest way to fix the trem is replace the 3 oscillator caps. The schematic I glanced at showed 0.01 (2 of them) and a 0.015 uF.
Replace all 3 and I'll bet you'll be back in business right away.
Good advice! While you're in there I'd also replace C25, with a 22 mfd/25v or better electrolytic. This is the cathode bypass cap across the 820 ohm resistor on pin 3 of the trem oscillator tube. If it's old and dried up inside it will just sit there looking good and not doing what it was supposed to, which was to raise the gain of the tremolo tube so the circuit would work right!

This cap is cheap so why not? I'd also replace the others of the same type in the preamp stages while I was there, for the same reason.

:food-smiley-004:
 

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It can, but it doesn't have to. What you must watch out for is the output end of the tank being close to the magnetic field of the power transformer, inducing hum. Usually the metal of the tank provides enough shielding but it can happen.

Shortening cables doesn't usually do much 'cuz they're shielded and that means they're not SUPPOSED to pick up hum! More likely it's a tube or a component failure inside the amp. Most reverb circuits from that era seem to pick up some hum no matter what you do but it should never be noticeable or a PITA unless you're really cranking the reverb knob well past 6 or 7.

There can also be a broken wire inside the spring tank that can cause hum.

Keep looking! It's worth it!

:food-smiley-004:
Thanks Wild Bill

Appreciated the uncomplicated answer. Now I just have to remember it for the future.

Dave
 
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