Marshall Valvestate vs100 reverb not working, here s what I tried

[smac4th]

I got my valvestate vs100 head in August from a friend for free because he said didn't work and because he no longer plays guitar. I replaced the preamp tube with a groove tubes 12ax7. When I got home I hooked the amp and everything worked normally other than both the clean and overdrive reverb channels. I made sure the rca cables where in the right ports and they were, I swithced them around anyway just to see it it will fix it, nothing. I put the rca cables back where they belong. I also tried a different rca cable and tried the same thing. I tried tightening and loosening the nuts holding each reverb pot and nothing. I checked the connections in the reverb tank and they appeared to be normall. When I shake or bump the amp I can hear her reverb working. The only thing I have not tried yet was testing continuity because I don't have a multimeter. This is my first amp with a reverb tank so this is a whole new field to me. Also I tested the rca cables and they both work so I know the tank it getting power. I also chesked the solder joints at each reverb pot and they apprear to be normall.
Any suggestions on what may be causing my reverb to not work? My guess is even though the wires are connected the tank is not getting a signal on the input but it is on the output.

[dwmorrin]

I recently had a Valvestate reverb give me a tough time. Turned out to be the solder joints at the RCA connectors on the PCB. Be sure to add those to your list of things to check.

This is actually tricky on these amp because if the reverb send jack has a open sleeve connection (no connection to IC1a pin 2) then the send signal will appear to work if you scope it or send it into an amp. But then it will fail to drive the tank. That's what gave me a tough time.

[Jazz P Bass]

When you do get a meter, check the reverb pan input & output coils (transducers).
The input side should read a low resistance (10's of ohms) & the output should read higher (100's of ohms)

[smac4th]

I checked the solder joints at the rca jacks and they are all clean, shiny and intact. Still no reverb. based on what I have experienced, would replacing the reverb tank defenitly fix the reverb issue even though I have not tested the tank for continuity?

[52 Bill]

I checked the solder joints at the rca jacks and they are all clean, shiny and intact. Still no reverb. based on what I have experienced, would replacing the reverb tank defenitly fix the reverb issue even though I have not tested the tank for continuity?

No. You have proven that the return circuitry and the tank output coil are okay (shaking the tank), but you have no idea if the drive problem is in the amp or the tank.

Here's a quick and dirty test of the tank. You have the cables plugged in correctly so that the one that hums when you touch the tip of the plug is connected to the output of the tank. When you shake the tank you hear the springs rattle through the speaker right? Now switch the cables going into the tank and shake it. Can you still hear the springs rattle through the speaker? If you can hear them even very softly, you have proven that the input transducer is okay. If you don't hear them, then the wiring or the input coil is bad.

[smac4th]

Here is what I got, the plug that hums when I touch it,when its in the output and I shake the tank the sound it makes is a very faint and is very hard to hear but it does not sound like the springs moving, sounds like thumping. When I connect the same plug to the input and then when I shake the tank you can easily hear the springs moving without having to listen for it. This would mean the input coil or input wiring is bad and means that its going to be either a fix or replaced?

[52 Bill]

Then the wiring or the coil on the output side of the tank is open circuit. Carefully inspect the two wires that connect the coil to the RCA jack. If the tank has plug on connectors check for broken wires where they crimp into the connectors.

Some tanks have the wires hooked under a metal tab used as a strain relief. This is a common stress/breaking point.

Without an ohmmeter, that's about all you can do, unless you have some sort of continuity tester.

[smac4th]

I found the problem. The solder joint was weak and broke very easily. Do to the location of the solder joint I am un able to fix it. I will be ordering a new tank tonight.