Traynor YGM-3 Reverb Fail

[Pryde]

Schematic attached

I have a vintage traynor yrm-3 with no reverb. With reverb maxed the signal gets slightly "thinner" but still no reverb.

-tank actually is NEW and is correct spec. (the old one was indeed bad with shorted a shorted input coil).
-cables have full continuity, cleaned and seated well.
-reverb footswitch jack is short grounded proper.
-tried new drive and recovery tubes with no luck.
-getting correct voltage on V5B plate (325vDC) and V6A plate (75vDC).

I am thinking I have a bad component in the circuit but not sure how to isolate without replacing everything. Any advice on how to proceed here? Thank you.

[Pryde]

Just bumping. Anyone have ideas on this one?
Thanks

[Chuck H]

You mention "-reverb footswitch jack is short grounded proper." but the schematic does not show a shorting jack. With a shorting jack the reverb will be switched off by default with no footswitch plugged in.

Set up as you have been testing, what is the DCR from the recovery grid to ground?

Have you checked for signal going into or coming out of the tank? It's actually touchy measuring signal from the tank because it'll likely be under 10mV. If you short your meter probes for a default reading, anything over that in the circuit is probably signal.

It might be good to know the cathode voltages for the reverb circuit.

[Jazz P Bass]

A 'shorted' input coil?

Usually they go open.

Anyway, try to narrow it down to the send or the return.

If you touch the return cables tip, it should make the amp hum.
If so, you then have to see that the signal is reaching the input tip.

Whichever one does not work, you will know from these tests.

Then we take it from there.

[Pryde]

Sorry for the poor terminology: The reverb jack has a tip shunt to ground. Either way no reverb with jack open or plugged in.
Yes the coil read open on the original tank not shorted sorry.

The amp hums when touching the reverb output tip but there is no hum when touching the input tip.

Pins 3/8 on V5 read 2vDC. Pin 8 on V6 reads 700mvDC.

[Pryde]

UPDATE:

It was C18 (560pf) cap. Traced signal and it was very low on reverb input side. Replaced it with a silver mica and reverb is good to go.

Thank you for the assistance as it got me to focus on the input side

[Jazz P Bass]

Good catch.

Silver mica, huh?

(SGM would be proud.)

[g1]

Yeah, they should have been called silver michael, in honour of their "inventor".

[J M Fahey]

Did you mail him the $5 check, the royalties for his inventing the silver mica cap in the first place?

If not, get ready for his Lawyer knocking your door.