Signal not passing through reverb pan.

[1WoodHippie]

I've got a BF Deluxe Reverb RI with the symptom of No Reverb. I can trace signal with a listener box all the way to the input of the pan, but not on the other side. It's got a brand new pan on it, and I've tried it with other known good pans and cables with the same result.

(The owner had a tech remove the PCB board with a hand wired Point to Point board.)

any ideas? I've just never seen one not pass signal through the pan at ALL if the pan is good.

thanks in advance.

[g1]

Maybe there is a short in the output cable? Or a short somewhere at the other end of the cable?

[1WoodHippie]

i've tried different cables. even with no output cable plugged in you don't get a signal at the output side of the tank. Ive also tried disconnecting the lead from the output jack in the amp so it's not connected to the return circuit and still don't get a signal coming out of the tank itself.

[g1]

Do you have a big signal going into the tank? The signal coming out can normally be about 1000 times smaller than the input signal.
If it is a small signal going in, I doubt you would hear anything coming out.

[Enzo]

So check the other end of the thing. Pull the plug from the OUTPUT jack on the pan, and with amp running and reverb control up part way, touch the tip of the plug with a finger. Do you get a loud hum from the speaker?

[mhuss]

Also check the tank input and output coils, to make sure they're not open. I just had one of those here this week (the output and input jacks were switched, that might have contributed ).

[Chuck H]

I think it's worth noting that signal does NOT pass through the pan. Ever. The pan is derived from two sets of transducers that are hooked physically, but NOT electrically, with springs. When the transducers on the input side are, uh, transducing, the vibration is transferred to the output transducers via the shaking of the springs. So the output transducers put out signal because the springs are shaking them. The same way a microphone puts out signal because your voice shakes a transducer inside.

I know this isn't an answer to your problem, but I hope it can help you understand what you're trying to troubleshoot and solve for.

Enzo is on the right track. If you have signal going to the input side of the pan, and you've tried other known good pans of the correct impedance, there may be a fault in the recovery stage that you have failed to detect as yet.

A nod to g-one too. You need to put about a half a watt into the tank to get only six or seven millivolts from the output transducers! So if the input POWER is weak the output will be almost undetectable by anything but the most sensitive amplification and hardly at all by your DMM. Voltage at the input is irrelevant without current. So, if you DO get amplification of noise doing enzo's test you can assume the recovery for the pan is working. Actually, you should be able to just turn up the reverb knob and jostle the tank. If the recovery stage is working a good pan will cause that reverb lightning that you hear when moving a live amp around.. If your recovery stage is working then test the signal going into the tank across a load of the same impedance as the tank input and calculate the actual power.

[1WoodHippie]

RESOLUTION: Turned out that the guy that wired this when he put in the hand wired board wired the reverb return to the footswitch/recovery tube with a shielded cable but tied the shield to hot lead therefore permanently ground out the grid. On top of that, he wired the footswitch jack itself BACKWARDS as in relation to Trem and Reverb. (using the shielded cable in the footswitch cable for the trem and not the reverb).

Anyway, all is good and just wanted to post a resolution in case any future "searchers" with the same problem stumbled upon this post.

[g1]

Not sure what happened at post #3 , but glad to hear you got it working!