Madison divinity 2 reverb dead

[boog]

Divinity_Ashton.pdf

The schematic above.

As the title says, dead reverb.
Cables are good, tank works(tested separate from the amp and in the amp), tubes are good, signal is seen on the scope everywhere it should be, both outs of the 4558(ic2) one of those changes with the reverb knob, Lm324n (ic1) has signal on the outs, +15 and -15v are correct, checked all caps on the recovery side, led is lit for reverb, and switches with a footswitch.
one odd symptom is that the signal makes the springs vibrate, and that changes with the channel level no matter where the reverb or master controls are set, and being fed a steady sine wave signal to the input jack.
I haven't actually listened to any of the signals other than directly out of the reverb tank and what's coming out of the amp to the cab.
I've overlooked ot checked something wrong, any ideas would be appreciated.

[Enzo]

Reverb is the drive circuit, the return circuit, and the pan and cables.

With aamp running and reverb up midway, pull the cable from the OUT jack on the pan and touch the tip with your finger. Get loud hum? You should.

You say the pan works and the drive works? Just do this: connect a cable from the pan OUT jack and connect that to some other amp. Just plug right into some other guitar amp. Play guitar through your amp and see if reverb comes out over there. That verifies all the drive and pan.

I don't find a sine wave very useful chasing reverb, as its even-ness doesn't give me anything to hear delayed. The reverb control and master volume neither one has any effect on reverb drive, drive comes way before them.

If your return doesn't work, then it should be straightforward. You have signal past the reverb control and at pin 1 (unmarked on schematic) of IC2? OK, how about the other side of the JFET? IS there ssignal on the left end of R64?

I'd suspect the Q3 circuit. COuld be a bad JFET or it could be the JFET is simply never getting turned on. A JFET is naturally ON until turned OFF by a voltage on the gate. So look to left center of drawing for that LED that works, and nearby Q12. Q12 is where the control signal for Q3. SO what happens on collector Q12? Does it toggle from like -15 to maybe zero wwith the footswitch? BAck over at Q3, is there a negative voltage on the gate holding it OFF? If you short Q3 S-D, does reverb come back?

[boog]

The return is not working, no hum, I did connect the output of the tank to another amp and had reverb, r64 did have a signal on the left side, I'll have to get it warmed back up and check q3 and q12

[Enzo]

Left side of R64 COULD be the main signal coming in from the right, so shorting Q3 would be a definitive test.

[boog]

Q3 seems to be working, I have -13 on the gate with the reverb off, and 0.12 with it on, signal is being switched on and off at the source of q3, if I turn the channel level way down I can hear the reverb, but when it's turned up I can't hear it, I do have the tank out where I can give it a thump, makes it easier to hear with the sine wave. Shorting s d on q3 didn't change anything.

[Enzo]

Um, you have signal all the way through to R64? Ought to be working. R64 open? The whole thing is IC2 and a few small parts.

[boog]

That's what doesn't make sense, it is working if I turn the channel level nearly off, I can thump the pan and hear it through the cab, but with the levels at normal you can't hear the reverb.

[Enzo]

Wait, if you whack the pan to crash the strings, you can hear that? Is it loud like normal or is it just you can hear it but not loud? I mean a spring crash is usually big.

You say the pan works, and works elsewhere, OK. WHat other amp was it tried in? ANy chance the pan works but is the wrong type? Basically the Fender tube driven reverbs want a 4AB2C1B pan, while most SS drives want a 4EB2C1B. WHat type is your pan? Less common 4FBxxxx would be fine too.

It concerns me you can't hear a hum touching the end of the return cable, yet get some signal anyway. That hum signal; ought to be huge.

Hey, I surely have done it, any chance the cables are backwards? NO hum touching the return cable, so any hum when touching the other?

[boog]

I'm pretty sure I tried touching both tables, I will again later today when I can get back to it.
I'm not near the amp now, I'm pretty sure it has the factory pan, I'll have to check.
I ran a signal from a function generator, into the front of a gk bass combo, it might not have been as loud as it should have been, I didn't pay attention to levels, just that it worked.
I didn't realize it was working at all until going through and checking q3 earlier, I just happened to turn the channel level almost off, reverb full on, then whacking the springs, it was not very loud at all but could be heard through the cab.
Something is definitely off, I've never seen just a signal vibrate the springs, even with the master and reverb at 0, turning the channel level up and down (with a sine wave into the front) changes the vibration of the springs, like they are resonating the signal, could be normal and I've just never noticed it?
I will do those checks again and post back later today, I'm curious if things are labeled wrong and it's as simple as being hooked up backwards, would be unheard of with these amps.

[boog]

Ok it was hooked up right, the pan is labeled 2bb3g (cy) inside, I cleaned up the rca jacks, that seemed to help a little, still no way loud hum, but it is working, actually playing guitar through it I can hear the reverb, not as loud as I'd expect it, maybe that is normal for this amp? And that is with the channel levels up where I couldn't hear it before, getting past a little crunch into heavy distortion you can't hear it.
it didn't work at all to begin with, so I might call it fixed.
This is the same one I posted about a while back that had a dead fx loop, and the guy complained that he didn't think the shape knob worked right, I changed the pot for that, it rolls off the highs from 8 to 10 on the knob, I'm not sure what else he is expecting.

[boog]

Just heard back from the owner, he said when it worked before it was kind of subtle turned all the way up, so we'll all that fixed, I did have to change the 4558 to get it passing signal, I think I forgot to mention that in the first post.