Vintage Traynor YGM-3 Tremolo Issue

[Pryde]

Hello Folks,

I got a Traynor YGM-3 that I am going to do a full electro re-cap on (all original from 1974) and some new power tubes.

I notice the amp has the tremolo signal bleeding into the reverb signal: With the tremolo controls turned off, as you turn up the reverb pot you can hear the "tick-tick-tick" in the audio signal.

Anyway to reduce or remove the bleeding? I would like to take care of this while I am in there if so. Thank you!

Here is the schematic link as well:

http://www.lynx.bc.ca/~jc/730911_YGM3_4.gif

[52 Bill]

You will need to find out if the ticking is being transmitted via the power supply or by induction (wire routing). Once you recap the amp, it may go away.

[Pryde]

OK then. I will get the recap going and see where it stands after that

I think others have used a grid-stopper resistor somewhere around the reverb recovery on vintage fender amps to stop the issue. I will need to look into it as well

[Enzo]

Are you sure it is the trem? Does changing the speed setting affect the ticking? Some guys discover their cell phones make ticking sounds if set on their amps, so never assume.

[Pryde]

Are you sure it is the trem? Does changing the speed setting affect the ticking? Some guys discover their cell phones make ticking sounds if set on their amps, so never assume.

Yes for sure the trem as the tick speed changes with speed pot

[Chuck H]

The schem isn't clear on WHERE things are grounded. If the problem persists after the recap it may be as simple as changing the ground, power supply node or both for either the reverb or trem. If the trem is currently sharing any ground nodes with the reverb you might just ground the trem with the power supply. This might be impossible if the reverb and trem share a footswitch jack since the ground for both is the same and unavoidable. On newer model Fenders they have a parallel B+ node dedicated to the trem that must help with decoupling. That shouldn't be hard to do and it may help.

[Pryde]

Alright folks I got the re-cap done and all went well there BUT

The tremolo ticking is still there as prominent as it was before. V6 A is the reverb recovery and V6 B is for the tremolo circuit.

a. I tried a new 12ax7 in V6 with same result.
b. In another forum someone had the same issue and changed R29 from 1M to a 1K. I went ahead and tried this and the ticking did decrease a lot but was still present. I don't know if this is the "right" fix as it is a drastic value change for that resistor.

Any help is appreciated

[Chuck H]

Change R29 back to 1M. The reverb tank impedance is a high enough and the output low enough that you are losing valuable signal. This can only mean turning the reverb up higher for the same reverb level.

Try bypassing R30 with a 22uf cap (- side to ground). If that helps reduce the ticking but the reverb level is too high you can increase R12 to bring it back down.

[Pryde]

Thanks Chuck H

I assume you mean to put a 22uf cap in parallel with R30 (- side to ground)? What voltage cap would be needed here?

[Chuck H]

Any rating over 10V is fine. There will only ever be a couple of volts on this circuit. And yes, I mean parallel. It's called "bypassed" because that is the cathode resistor and the cap will be bypassing AC across the resistance. This raises the gain of the stage but also effectively eliminates any cathode coupling between the two triodes. It may, or may not help. Not much trouble to try.

[Pryde]

OK I tried bypassing R30 with 22uf cap and it seamed to make no difference in the thump/ticking.

I also tried a 1k grid stopper into pin 7 on V6 tube (keeping the 1M grid-leak in place) but still no luck.

Any other ideas? Thank you.

[Chuck H]

Any other ideas? Thank you.

Just changing ground locations. Make sure the grid 0VDC reference resistors, cathode and any dividers for the tremolo are not sharing any ground points with the reverb circuits. The farther away the better. You might even isolate the footswitch from the chassis so it may be grounded with the other tremolo circuits. Looking at the schem I see that all the power supply nodes are separate, so that's as it should be. But did you use the dual cap cans for the filter replacement? Sometimes those can caps can couple signals. Your forced into sharing grounds, the caps often have a higher than ideal impedance (even new) and everything is wrapped together in the same can. It only takes a tiny amount of coupling to be audible on the reverb circuit because the gain is generally very high. Ground points and power supplies can couple enough to be a problem. Make sure they're separated as much as possible.

[madkatb]

Have you checked all the components in the tremolo section? Resistors and capacitors still reading the right value? Tried chopsticking those components? It seems that most of the causes of ticking originate with signal path or ground issues but those components are all 40 years old.

[Pryde]

Here is a layout of the re-issue ygm3. this vintage one is pretty much wired identically to the picture. Any thoughts on re-grounding certain components to different areas? Also, I used JJ cap cans for the new filter caps and just connected the original wiring to them.

edit: the forum will not let me attach anything so here is a link to the re-issue service manual. Page 8 has a nice color layout which is how my vintage one is wired:

http://traynoramps.com/downloads/servman/smygm3.pdf

[g1]

Here's that service manual