Traynor YCV-40 No Reverb

[Enzo]

Sounds right, in the schematic above we have a 100 ohm resistor to ground in the drive ccircuit.

[ca7922303]

Sounds right, in the schematic above we have a 100 ohm resistor to ground in the drive ccircuit.

Could u2 be an issue, replaced u1 previously?

[g1]

You need to get the return side of the circuit figured out first. Right now it doesn't make sense.
The test Enzo asked you to do in post #4 was to find out which side gave hum when touched with your finger, not just hum. And that hum should change in volume when you turn the reverb control. Double check that it is the white cable that gives the hum when touched. The one giving the hum is the return cable.
If so, the hum indicates that the 'return' side of the circuit is working. Then you have to get a spring crash when you shake the tank with the correct cable connected to the tank output.
Set the amp for a loud hum when touching the return cable, with reverb and volume controls up. Connect the tank output to the return cable. Give it a good shake or rub the actual springs with your finger. Can you get sound from the tank?

[ca7922303]

You need to get the return side of the circuit figured out first. Right now it doesn't make sense.
The test Enzo asked you to do in post #4 was to find out which side gave hum when touched with your finger, not just hum. And that hum should change in volume when you turn the reverb control. Double check that it is the white cable that gives the hum when touched. The one giving the hum is the return cable.
If so, the hum indicates that the 'return' side of the circuit is working. Then you have to get a spring crash when you shake the tank with the correct cable connected to the tank output.
Set the amp for a loud hum when touching the return cable, with reverb and volume controls up. Connect the tank output to the return cable. Give it a good shake or rub the actual springs with your finger. Can you get sound from the tank?

White cable does hum, hum increases with volume increase, reverb is on full, plug white cable into output of 4eb(new, works in twin reverb I have), but I am not getting anything when bumping tank. I've tried white cable in both input and output, red cable in both input and output, white cable only, white cable w)red cable installed and other reverb tanks. No results?

[g1]

When you have the hum from touching the tip of the white cable, does adjusting the reverb control make the hum increase and decrease?

[ca7922303]

When you have the hum from touching the tip of the white cable, does adjusting the reverb control make the hum increase and decrease?

Yes, adjusting the reverb control does make the hum increase and decrease.

[g1]

Then the return circuit is working. And a good tank into it should give you some sound when you shake it. It doesn't really make sense, as the reverb cable seemed to check out.
But they use very cheap cables in these. Do you have another cable you can swap in there, maybe from the Fender?

[ca7922303]

Then the return circuit is working. And a good tank into it should give you some sound when you shake it. It doesn't really make sense, as the reverb cable seemed to check out.
But they use very cheap cables in these. Do you have another cable you can swap in there, maybe from the Fender?

Working on swapping cables. Back momentarily.

[ca7922303]

Then the return circuit is working. And a good tank into it should give you some sound when you shake it. It doesn't really make sense, as the reverb cable seemed to check out.
But they use very cheap cables in these. Do you have another cable you can swap in there, maybe from the Fender?

Swapped twin reverb cables and still no reverb tank sound.

[ca7922303]

Then the return circuit is working. And a good tank into it should give you some sound when you shake it. It doesn't really make sense, as the reverb cable seemed to check out.
But they use very cheap cables in these. Do you have another cable you can swap in there, maybe from the Fender?

I'm able to hear a very faint sound when bumping the reverb tank. After swapping cables on this one, board has to be loosened to get cables off and I may have had a cable loose, but they are tight now, but no reverb when instrument plugged in.

[Enzo]

If shaking the pan results in only a faint sound, then of course guitar input won't result in reverb either. We need to solve the weak return circuit.

[ca7922303]

If shaking the pan results in only a faint sound, then of course guitar input won't result in reverb either. We need to solve the weak return circuit.

What do you suggest ?

[g1]

I guess the hum you are getting from the return cable is not very loud. I should have specified you should be able to get a high volume hum when touching the return cable with reverb and volume controls turned up.
You said you have replaced U1, and the reverb control seems to work. Is the rest of the amp functioning correctly?
There is not much left aside from the connections and other components between the reverb return jack and the reverb pot.

[Helmholtz]

Sorry, if I missed something.
To get the hum with the return cable, it doesn't require a good shield conductor/connection.
But a real signal needs the return path.
Sometimes the outer crown shaped part (dunno the correct term) of an RCA plug doesn't make good contact with the jack's counterpart and a litlle inwards bending might help.

So, a broken cable shield or bad plug connection might be the problem.
I would feed some signal source to the return input via the return cable.
Signal source could be a guitar or an audio player.

Or just replace the return cable with a known good RCA cable (e.g. from some audio equipment).

[g1]

Sorry, if I missed something.
To get the hum with the return cable, it doesn't require a good shield conductor/connection.
But a real signal needs the return path.
Sometimes the outer crown shaped part (dunno the correct term) of an RCA plug doesn't make good contact with the jack's counterpart and a litlle inwards bending might help.

I think this was addressed in posts #13 thru #15. And return cable was swapped out above.