Rectoverb Series 1 Issue

[jdecaire]

Hi All,

I have owned a Single Rec Rectoverb Series 1 for about 6 months now. Up until now the amp has been problem free, however, earlier today I was playing on the clean channel for a while and went to switch to the drive channel and the amp just went silent. It played completely fine yesterday, no issues on the gain channel and no telltale signs of tube failure that I was aware of. I have tried moving the tubes around (swapped V2 V3 with V4 V5 tubes, then tried swapping V1 and V2) and none of the swaps made a difference. I completely re-tubed the amp when I bought it in April and do not have a ton of playing time on the tubes so I am thinking they should be in good shape.

I continued to play around with the lead channel and noticed that there is actually a faint signal coming from the channel when I turned up the master, so it doesn't appear that there is an issue with the master volume pot.

Does anyone have an idea of what the issue could be? Or more ways I can help diagnose the problem?

Any help is much appreciated!

Thanks,
JD

 

[cyber104]

First off - check to make sure your speaker cable is good.

Then disconnect the footswitch and switch channels via the manual switch on the back.

let us know how that goes

 

[jdecaire]

First off - check to make sure your speaker cable is good.

Then disconnect the footswitch and switch channels via the manual switch on the back.

let us know how that goes

No such luck. Tried a new speaker cable and manually switching the channels and it is still doing the same thing. The signal seems fine to the clean channel but the lead is super quiet and muffled.

Any other potential suggestions?

 

[domct203]

If the Green channel is working fine, I would suspect a bad pre-amp tube. If you look at the Tube Task Chart on page 16 of your manual you will see that V3 is used only by the Lead channel, V2 is shared between the channels (V2A=3rd Stage Rhythm, V2B=3rd Stage Lead).

http://www.mesaboogie.com/media/User%20Manuals/singleRec_v1.pdf

I know you said you changed tubes, but there could still be a bad one in there. I would swap V3 with a known good tube to see if anything changes, if no change try V2. Just remember that V3 (& V4) are cathode follower positions, and those positions can and will wreak havoc on weak/poor quality tubes. Avoid any New Sensor brand tube in those positions. New Sensor brands include Sovtek (also Mesa Russian-1), Electro-Harmonix (also Mesa Russian-2), Tung-Sol re-issue, & Mullard re-issue. Stick with either JJ (current Mesa 12AX7), or Chinese (eg Shuguang/Penta) 12AX7's there.

If none of this helps it is time to visit a tech. You could have an LDR in the switching/muting circuit that has failed.

Dom

 

[jdecaire]

If the Green channel is working fine, I would suspect a bad pre-amp tube. If you look at the Tube Task Chart on page 16 of your manual you will see that V3 is used only by the Lead channel, V2 is shared between the channels (V2A=3rd Stage Rhythm, V2B=3rd Stage Lead).

http://www.mesaboogie.com/media/User%20Manuals/singleRec_v1.pdf

I know you said you changed tubes, but there could still be a bad one in there. I would swap V3 with a known good tube to see if anything changes, if no change try V2. Just remember that V3 (& V4) are cathode follower positions, and those positions can and will wreak havoc on weak/poor quality tubes. Avoid any New Sensor brand tube in those positions. New Sensor brands include Sovtek (also Mesa Russian-1), Electro-Harmonix (also Mesa Russian-2), Tung-Sol re-issue, & Mullard re-issue. Stick with either JJ (current Mesa 12AX7), or Chinese (eg Shuguang/Penta) 12AX7's there.

If none of this helps it is time to visit a tech. You could have an LDR in the switching/muting circuit that has failed.

Dom

Thanks Dom, I'm planning on picking up a couple JJ's tonight and I will try switching V3 and then try V2 if the first didn't fix it. I will let you know how it goes.

 

[jdecaire]

Tried new a new pre-amp in V3, and the cycled another new tube through each spot and nothing fixed the issue. I brought it in to a store that used to be a Mesa dealer and he mentioned that he had a similar issue with a Nomad a while back and it was some sort of transistor that had to do with the switching function.

I am by no means an expert with this amp, but is this a possibility? I will likely have to find a tech in my area to fix it, just wouldn't mind having a starting point for the tech to look at.

 

[cyber104]

I think it's time to take it to a good tech

I don't think you need to worry about giving the tech a "starting point" ;-)

Any good tech will find the issue no problem - in fact - most techs just want to know the symptom - they take the customer diagnosis just as a courtesy and just let it go in one ear and out the other.

 

[jdecaire]

Fair enough! I have decided to just take the head in to a tech. I will let you guys know what the end result is.

 

[3124+]

I have been using New Sensor tubes in cathode follower positions for years. No issues whatsoever. Also, have a look at the spec sheet for the JJ 12AX7/ECC83S. It is a spiral filament tube with maximum cathode voltage of 180VDC. The Single Rec has 218VDC on V3 cathode.