Rectoverb 25w troubleshooting. Only one channel & no sound

[snails]

Hello all,

I picked up a used rectoverb 25w a few months ago and have been having some issues pop up. At first, it blew a fuse which was the cashed by a bad power tube. Now, when I went to power it up yesterday I found that there was zero sound coming from it except for a light crackling, and the led light for channel 2 is the only one that lights up. Even when I manually switch to channel 1, the led corresponding to channel 1 doesn't light up and it stays on channel 2.

I'm assuming that this is being caused by a preamp tube, maybe V1A, V1B, or V2A? It's the ability to not switch channels that's also throwing me off...though I don't have a lot of experience with having to troubleshoot amps.

I'm hoping that since I bought it used it's just a quick fix. I'm starting to get a little paranoid that I bought an amp that's plaqued with problems and is unreliable.

Thanks in advance!!

 

[bandit2013]

I hate to say this..... but I am going to do so.... you may have a compromised component in the switch gear used to select channels, mute the circuits during channel changes, and select the array of relays or transistors that define each channel. The transients caused by tube failure and blown fuse may also affect some sensitive components in the muting circuits or channel logic. I killed my TC-50 when the fuse blew out (had the Mesa NOS Siemens EL34 tubes in at the time that occurred). I know it is a different amp and uses a different switching logic (midi) vs analog. The mute circuits on the other hand are quite similar. If there is any similarities between the two amps it may be in the muting circuits used to change channels along with the relay drivers.

First question: did you by any way remove the chassis from the amp shell following the fault? If the answer is yes, there is a slim chance one of the internal ribbon cables used to bridge circuit boards together may be loose or unconnected (not likely but slim chance). If you did not remove the chassis from the shell, you can rule this out completely.

There may be hope, if you have the footswitch plugged in, try removing it and try using the mini toggle to change channels. I did see you attempted to change channels with the toggle but was the footswitch plugged in? it could be related to bad cable or not correct type of cable (not sure if this amp uses a TRS type). Still if the cable was bad you should be able to change channels with the toggle regardless of the footswitch (I would assume).

A faulty or bad preamp tube may result in no sound but should not prevent the amp from changing channels. If you think it is a preamp tube, for a diagnosis, you can remove all of the preamp tubes from the amp (leave the power tubes in if they have been replaced) or you can remove those as well. If the amp has a rectifier tube, leave that installed (general note, however the Rectoverb uses silicon diodes so not issue there). Without the tubes installed, the amp should still change channels and LEDs. Obviously there will be no sound. I highly doubt the issue is tube related.

Best advice I can give on this: Call Mesa Technical service. If there is a simple fix they will tell you.

 

[Monsta-Tone]

:shock: Bandit.....You beat me to it!

One thing to check is the channel select switch on the front of the amp.
If you are using the footswitch and it does not change channels, the switch on the amp itself may be set wrong.
That would eliminate one problem.
A faulty tube will not affect switching in any way.

I would double check the footswitch/front panel switch before calling Mesa just to rule out a potentially embarrassing moment.

If you are using the front panel switch and the footswitch is not plugged in, there is a definite issue.

If you are using the footswitch and the front panel switch is set wrong, it should start working once the switch is in the correct position.

If you are using the footswitch and the front panel switch is set correctly, (assuming that the amp changes channels with the front panel switch but not the footswitch) try a new cable between the amp and the footswitch.


Here is a link to the manual, in case you don't have one since it was bought used:
http://mesaboogie.com/media/User%20Manuals/Recto-Verb25_131119.pdf

There are some good tips for troubleshooting tube issues by yourself. Just be careful and follow the instructions or look up how to change tubes if you do not know how.
If you rule out all of the easy things before calling Mesa, it will definitely save you some time.

 

[Monsta-Tone]

The Rectoverb 25 is a rock solid amp. I used one for about a year gigging and it always worked! I sold it to a friend when I wasn't playing much and deeply regret it!

It is very possible (as Bandit said) that something else was damaged when the power tube failed, or if someone was inside the amp monkeying around.
If you don't know your way around a tube amp, it's best to let someone else work inside it. There are deadly voltages inside, trust me it hurts a lot if you touch the wrong thing!

Any guitar or speaker cable should work.
This amp uses a TS (Tip/Sleeve) connector.
There is only one function to switch.

 

[snails]

Thanks guys! I'll try to play around a little bit more tonight to see if I happen to have some luck. Otherwise I guess I'll be calling Mesa on Tuesday and maybe taking it in to an authorized tech on Wednesday.

I'll keep you posted!

 

[j1mmyd33]

Did you ever figure out the problem?

I experienced issues like you mentioned when I accidentally plugged in a dual foot switch into the channel switching jack. I very quickly took it out as it did not sound healthy at all.

The lack of volume etc. is a preamp problem but might be an unrelated issue.