Reverb not working on my amp?!?

[toejam]

I just noticed that the reverb is no longer working at all on my Mesa F-30 combo. The amp's got 2 EL84s and 4 12AX7s. The amp plays fine, so it can't be a tube problem, not to mention the fact that there's a spring reverb tank in a leather-type bag on the bottom of the cabinet, so I doubt tubes would have anything at all to do with it.
The wire coming from the bag is hooked up to the underside of the chassis, and I unplugged it and plugged it back in. I turn the reverb level control from all the way down to all the way up, still nothing, with and without the footswitch connected. What could the problem be? If I take the tank out of its bag, what would I look for to possibly diagnose this problem? [img]graemlins/help.gif[/img] Everything else on the amp and footswitch work fine.

[mm2002]

Re: Reverb not working on my amp?!?

I'm far from an amp expert but I think that one of the 12aX7s actually drives the reverb so that tube may be bad. There is really very little that could go wrong with the reverb tank itself (in my experience) so it could be the tube or ???.

[toejam]

Re: Reverb not working on my amp?!?

Hmm, maybe it is a tube? I don't know. The amp seems to be operating normally and sounds normal. This is my first tube amp, so I don't know about if one of the tubes drives the reverb or not. The manual gives a description of the four preamp tubes and that each 12AX7 contains two separate Triodes. From left to right it's V4 with an A section and B section, V3 A and B, V2 A and B, V1 A and B.
Description of tube functions:
V1A = Input stage both channels.
V1B = Clean channel.
V2A = 2nd input stage both channels.
V2B = Channels 2& 3 boost stage.
V3A = Channels FX send.
V3B = FX return.
V4A and V4B = Phase splitter/output.

[charvel750]

Re: Reverb not working on my amp?!?

Joe, when I bought Matt's (OSG) Marshall the UPS apes caused the springs in the reverb to come undone. They are connected on each end of the reverb tank. I'd open it up and look to see that the springs are still properly stretched across. Look for any other loose connections too.

[toejam]

Re: Reverb not working on my amp?!?

I took it out of its pouch and all the springs are attached. If I tap it or shake it around a little, I can hear it echo through the speaker, but I have no idea what the problem is. [img]graemlins/scratchhead.gif[/img] I disconnected the wire on the amp and the one on the tank, plugged them back in, still nothing. Maybe it's one of the two smaller wires? They look fine. I didn't really look inside to see about any other connections, but I really don't know what to look for. Maybe I'll just take it to a semi-local shop I trust (haven't been to him in a while) and see if they can figure it out.

[toejam]

Re: Reverb not working on my amp?!?

I don't know, but I doubt it, as there's actually two separate reverb controls (one for each channel). That would be strange if both went at the same time. [img]graemlins/scratchhead.gif[/img] Maybe I'll pull the chassis out later and take a look.

[jgcable]

Re: Reverb not working on my amp?!?

Does the channel switching work properly? Because the F-30 has long-tailed reverb it is connected to the channel switching circuit. Try cleaning the reverb pot. If that doesn't work try some freeze mist on the pot. Once the pot is frozen the reverb should kick on and then turn off when the pot melts. If so.. replace the pot. I doubt that is the pot though. Does the effects loop level control that is on the back have anything to do with the reverb?

[toejam]

Re: Reverb not working on my amp?!?

Originally posted by jgcable:
Does the channel switching work properly? Because the F-30 has long-tailed reverb it is connected to the channel switching circuit. Try cleaning the reverb pot. If that doesn't work try some freeze mist on the pot. Once the pot is frozen the reverb should kick on and then turn off when the pot melts. If so.. replace the pot. I doubt that is the pot though. Does the effects loop level control that is on the back have anything to do with the reverb?

<font size="2" face="Verdana, Helvetica, sans-serif">Yes, the channel switching works properly on both the amp and footswitch, just no reverb for either channel. It's weird, because I use only a tiny bit of reverb on the crunch channel and set the clean channel reverb for a little more, so I usually just keep them on and don't really switch them off (both reverbs are footswitchable on/off with the same switch).
The clean channel footswitch LED lights up green, the second channel normal doesn't light up (only lights up red when the contour boost is kicked in). At first I thought the footswitch was messed up when the reverb wouldn't switch, but I disconnected it and just did it manually at the amp and everything else works fine, just no reverbs. The loop level control has nothing to do with the reverb at all, and I even tried that just in case.

[jgcable]

Re: Reverb not working on my amp?!?

Try the freeze mist on the reverb pots and see what happens. Also, I believe that long tailed reverb also has some circuitry on the board that could be the problem. The circuitry controls leaving the reverb on during channel switching.

[mccullpl]

Re: Reverb not working on my amp?!?

bad or broken solder joint on the reverb pot? or a bad pot?