The Amp Garage

Looks like a mouse had a field day in there! Test the PCB board for mouse urine connectivity and try to identify the chewed wire replacements. I'd say it is 50/50. I the board is conductive, then forget it.

@sonicmojo for what it's worth - here are some schematics I found years ago when I started cloning my Vox series. JMI used some ceramic phono PU systems to get the spring reverb system working - just like on the stand-alone Reverb Unit they made in the Sixties (Cliff Richard Reverb Unit). Cheers Cl...

Step thru the normal circuit up to the PT with a set of headphones protected with a blocking cap , or couple the outputs to another amp to see / hear where the reverb is joining in. That amp as you know should only have the verb on one channel. Be careful that the high audio levels do not blow out ...

Great! Must have been feeding back from the screen, I think. Interesting.... So you think it was a feedback loop from the first power tubes filter node that was unconnected and possibly moved down the line to the other nodes? The reverb did not sound nearly as good coming from the normal channel, k...

Try a 12AU7 for the reverb driver. Hum any better? I had tried a couple of different tubes before and no help, BUT.... Issue is solved! No more reverb on Normal channel and no more hum. It was actually the 22uF filter cap C32 for sure. The cap has the connection to the "Z" on the schematic which we...

As for the schematic, I don't get why TP15 says 4.2V. I get 200+ something as I would expect. All those voltages inside an oval are signal voltage, not dc voltage. They are based on the 37mV @1KHz test signal applied to the grid of the first preamp ***AND*** having the controls set to a default set...

Yes, caps look untouched. I'll try that first, especially the 22uF caps that connect to the "X", "Y", and "Z" connections.

Could a leaky/bad filter cap create crosstalk like this?

So the original reported problem with this amp was that it would not turn on. The fuse retaining clip appears to have been installed backwards and created bad connections and load and blew that fuse so I bent out the tabs, installed a fuse and it works again. Took me a few minutes to figure out why ...

Seems odd to me that R34 and C18 are in the order they are in. I don't think that is the problem but seems off.

martin manning wrote: ↑Tue Apr 02, 2019 10:29 pm How about C11? If that is bad, the channels will talk to each other.

Wouldn't have pulling the V2 tube fully disconnect any possible crosstalk there?

Thanks for replying and I wish someone had messed with it. Apparently it is the original owner and bought it new. I don't see any mods or see any solder joints affected on the upside down preamp control board. Attached is a pic if you see anything I don't. If I pull V2 or disconnect the jumper for t...

Hello, I've got this issue with an apparently STOCK Twin Reverb Reissue from the 2000s probably where the reverb has a hum when turned up and there is about 3/4 reverb effect when using the normal channel. Has anyone had this issue and know of an obvious place to look for where the fault may be? I'v...

Can't help myself. The newly acquired Reverberocket 2 has now gone into a head cab that I just made for it actually out of another box with working similar dimensions. It is working quite well and sounds pretty much just the same as the other one even though the smoke incident. I bought the tolex an...

Yes, not a big fan of reissues. I’ve got a Twin Reberb for repair that has a low frequency reberb hum when reverb is turned up and about 3/4 reverb coming through from the normal channel. Only gets vibrato for the reverb on the normal channel. Probably a similar weird extra component thing. I’ll pos...