Help troubleshooting reverb

[Dr Tony Balls]

Hi all, just want to throw this up here and see if anyone has ideas. I'm working on a Traynor YRM-1 (schematic below) that is not producing a reverb signal. First step is to check voltages in the reverb circuit, and i'm doing this with the reverb pan disconnected. I'm seeing the correct 120VDC on the plate of V2 and at the positive end of C18, but i'm also reading 120VDC on the negative end of C18! I tried replacing that cap twice and keep getting the same result, and verified it with two different meters. With the cap removed I still get the 120VDC at its positive eyelet, but get 0VDC at the negative eyelet, as expected. So why does it appear that caps in this position are not blocking DC? Any ideas?

https://www.thetubestore.com/lib/thetub ... ematic.pdf

[sluckey]

The cap is an electrolytic. With the tank disconnected one end of the cap is connected to nothing. The electrolytic leakage allows the dc voltage to leak across to the other side. Connect the pan and the dc voltage should go away. If the voltage is still there check the input resistance of the tank. If the input coil is open, you may have just found the problem. Change the cap when you change the tank.

[FUCHSAUDIO]

A few easy steps to test a reverb: To test the pan, shake pan. Do you hear rattles from the springs crashng ? If no, you have a circuit problem in the return amp. If yes, switch the wires and try again. You should hear a crash again, but lower in level. You are "listening" to the input transducer. That means the pan should be okay. If you get no sound from the input end, then it's a bad pan.

To test the circuitry...Take the output of the drive side ( the input to the pan) and put that wire into the return (from the pan). If you get a big gain jump when you turn up the reverb knob, then you know the driver side is working....not much to a reverb circuit. drive-pan-return...can't be too many places to lose signal really.

[Stevem]

A very quick and easy way to test both the send and recovery circuit in a amp like that is to jump a 470K resistor across the tip of each RCA jack .
After you do this if both circuits are working you will get a volume boost when you turn up the reverb.
You should also short across the shell of each RCA jack with a clip lead for ground connection .

[Stevem]

A very quick and easy way to test both the send and recovery circuit in a amp like that is to jump a 470K resistor across the tip of each RCA jack .
After you do this if both circuits are working you will get a volume boost when you turn up the reverb.
You should also short across the shell of each RCA jack with a clip lead for ground connection

Also note that on the schematic it states that a resistance check of the transducer at each end of the pan should test out at about 160 ohms if they are not open or if there is not a broken wire at either RCA jack as is many times the case,