122RV Reverb Amp Problem

**Hiwatt** · 08-02-2011, 04:23 AM

I recently got a 122RV. The main amp works fine, but the reverb amp was dead. I traced the problem to Q1, and replaced both Q1 and Q2. Reverb started to work, albeit at a very low volume with the pot turned all the way up. I already did the following with no noticable changes

Cleaned all of the tube pins/sockets.
Cleaned and verified the pot
Used another set of known good tubes (I used EL84s instead of the 7189s)
Checked all of the voltages which were good but a little high (my line voltage is 121 VAC)
Measured all of the resistors
Checked all electrolytic caps (except the can, but the voltages are good with no sag)
Resoldered the tube board
Tried another speaker
Traced signal flow and both tubes are outputting
Verfied that both limiting bulbs were ok

To sum it up, the output is clean but I can't get any real volume out of it. (It is nowhere near 15 Watts)
Any Takers?
Thanks

**Hamman** · 08-02-2011, 02:43 PM

From a different thread.......by Todd (BlueOliveB3)
Many RV Leslies had their reverb systems removed when the reverb amp Leslie came up with failed, as a large number of them seem to do, I've run into a few and never have I seen one that worked. I've never sat down and troubleshooted one (maybe I'll grab the one sitting at the shop and fiddle with it) but I suspect the two-transistor(!) input stage is at fault...they should have just used a low-noise 12AX7 for reverb recovery at that time like the Hammond reverb amp used. The twin sets of louvers were for 251 and 251RV applications, for other models they'd block off one of the sets. It kept the number of different cabs spec'ed from Cal-Craft (Leslie's cabinet supplier during the Pasadena era) to a minumum to save production costs, since the same cabinet could house a 122RV, 147RV, 251, or 251RV. When a technician removed a faulty reverb system another block-off would typically be installed. In the 147RV that dspiffy and I have we just removed the 6X9 and put the box back in place. I prefer a dry Leslie and just use the reverb in my A-100...the 12" reverb speaker makes for a lush tone.

**Hiwatt** · 08-02-2011, 04:14 PM

Before posting I did read the thread by BlueOliveB3, and it did help me find the bad transistor. Other than that the thread doesn't offer much repair help but rather discusses the philosophical merits of repairing the RV amp. Regardless of the prevailing opinion I would still like to repair my amp and have a fully functioning cab, so any technical help would be much appreciated.
I should mention that even with the low volume on the reverb channel I can hear that the signal is somewhat muddy, almost like a L-100 with both reverb tabs depressed.

**Hamman** · 08-02-2011, 04:38 PM

Have you tried another type of input to the amp? Maybe the issue is in the reverb unit itself and not the amp.FWIW

**Hiwatt** · 08-02-2011, 08:12 PM

That is a really good suggestion. Tonight I'll try to inject an audio signal directly into the 12AU7.

**Hiwatt** · 08-03-2011, 05:43 AM

FIXED! The blocking cap between the reverb tank and the recovery amp was bad. Replaced the cap and it works great now. Thanks for your help, Hamman.

**Corworld** · 07-19-2012, 12:19 AM

Had the same issue with my reverb amp. If anyone needs a look at what is going on I made a video show the various issues I've seen.

http://www.youtube.com/watch?v=b0u205VAGLY