Traynor YCV-40 No Reverb

[Helmholtz]

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

Probably, yes.
But sometimes one of the cables doesn't have its shield connected at both ends to avoid a ground loop.
So the cables might not be interchangeable.

[ca7922303]

[QUOTE=g1;n942545]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.

[/QUOTafter I soldered in u1, I checked for continuity from all right(8) legs going outward to the next component on each trace, and all showed continuity. If any one of those legs has a weak solder joint, could that explain the no reverb issue, even though they all show continuity?

[ca7922303]

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).

I'm gonna remove the board and tighten the outer ground shield on both cables just to be sure.

[Enzo]

This shouldn't be this hard. I fear we are not communicating 100% somewhere in this process.

I suggest you apply some test signal to the return jack, doesn't much matter what.. Then trace it through the caps and the single op amp with a scope or metr or signal tracer.

[ca7922303]

This shouldn't be this hard. I fear we are not communicating 100% somewhere in this process.

I suggest you apply some test signal to the return jack, doesn't much matter what.. Then trace it through the caps and the single op amp with a scope or metr or signal tracer.

Ok, have a signal generator hooked up to the return cable and a dmm. The board is installed components down, and is a real bear to get out, so I'm looking at solder joints only. Where can I go with this to get it traced? Thanks for your help.

[ca7922303]

This shouldn't be this hard. I fear we are not communicating 100% somewhere in this process.

I suggest you apply some test signal to the return jack, doesn't much matter what.. Then trace it through the caps and the single op amp with a scope or metr or signal tracer.

Ok, traced signal from return jack and signal stops on backside of c63 and both pins of c12.

[ca7922303]

This shouldn't be this hard. I fear we are not communicating 100% somewhere in this process.

I suggest you apply some test signal to the return jack, doesn't much matter what.. Then trace it through the caps and the single op amp with a scope or metr or signal tracer.

C12(22u), C12(9.85n). Replace C12?

[ca7922303]

C12(22u), C12(9.85n). Replace C12?

Meant C12(22u), C63(9.85n) Replace C63? Also, can I remove C63 and use something in lieu of C63 to test until I can get one?

[ca7922303]

Meant C12(22u), C63(9.85n) Replace C63? Also, can I remove C63 and use something in lieu of C63 to test until I can get one?

Would either one of these two film capacitors work: 224J 100v(green), 1000pf 400v(red)?

[ca7922303]

Would either one of these two film capacitors work: 224J 100v(green), 1000pf 400v(red)?

Replaced C63, signal goes thru C63 to C12 now, bouncing reverb tank produces much louder sound now, but no reverb with instrument plugged in. Will do signal trace again. I noticed signal at different times depending on which component I hit. May have been R68/R69, which both read at 592@200k resistance range. Schematic shows them to be at 120k.

[g1]

If you have any intermittent signal issues you should resolder all the connections in that circled area of the drawing in post #32 above.
Continuity checks with the meter will not always find bad solder because the meter probes can restore contact while you are checking. What happened with C63 might even have just been bad solder that got fixed when you replaced it.

[Helmholtz]

If you have any intermittent signal issues you should resolder all the connections in that circled area of the drawing in post #32 above.
Continuity checks with the meter will not always find bad solder because the meter probes can restore contact while you are checking. What happened with C63 might even have just been bad solder that got fixed when you replaced it.

C63 (47p) is in the NFB path of the opamp and rolls off HF gain. The opamp should work without it.
I could only imagine it was shorted.
(Its value should not be changed.)

[ca7922303]

If you have any intermittent signal issues you should resolder all the connections in that circled area of the drawing in post #32 above.
Continuity checks with the meter will not always find bad solder because the meter probes can restore contact while you are checking. What happened with C63 might even have just been bad solder that got fixed when you replaced it.

Have signal thru all components in red circle now, but when I touch I put jack to chassis, signal goes away on about hf of everything. Isolated input jack from chassis with masking tape and signal comes back. Bounced reverb tank makes noise, but no reverb with instrument used in. Reverb tank still makes noise when bounced also with instrument plugged in , but no reverb. R68. & R69 are reading about half of 120k.

[Helmholtz]

R68/R69 must be measured out of circuit, lift one end of each.

See if you have 12V at U1 pin 5 and pin 7.

[ca7922303]

R68/R69 must be measured out of circuit, lift one end of each.

See if you have 12V at U1 pin 5 and pin 7.

U1 pin#5 & #7 have 12V.