Mesa Rectoverb makes no sound...

[mesaman]

I have what I hope is an easy question:

I have had a Mesa Rectoverb 50 watt combo for maybe 6 year now, purchased new, and have never had problems. I replaced the power tubes a couple times, but not the pre-amp tubes [always sounded great, so I never thought there was a reason to switch preamp tubes].

The amp was working just fine a couple weeks ago at gig volume, after which I took it home and let it sit until today. Now, when I turn the amp on, I only barely get sound when I turn the volume to ten. It seems like the pre-amp works, but the power amp is not connected [??]. Does this make any sense? The power tubes glow as they should and are relatively new.

Any ideas what the problem could be? I saw a post about an F-50 on a mesa boogie forum, with a similar sounding problem that was corrected upon replacement of the "PI" Could someone explain further?

Thanks.

[tms13pin]

The PI is the phase inverter... that would be the last preamp tube in the
chain before the power tubes.

Do you use your F/X loop?

One thing to try is to take the send from the f/x loop out and put it into
another power amp of some kind or a something you have with a headphone
jack and see if you're getting signal out of it. You can plug phones into your
recording out jack too and see if you're getting signal there. If so, it isn't
a problem with your preamp. You can plug your guitar directly into the return
jack and see if you're getting anything out of your power amp.

I had a Mesa MkIII that had no sound coming out and when checking out the
f/x loop jacks I found that I had a bad jack and when I replaced it, everything
worked fine. The return jack is normalled to the send jack... nothing plugged
into the return and the send goes straight to it. If you plug into the return
it'll break the connection to the send. In mine, that normalled connection
wasn't being made. If I looped a cable from the send to the return, all
was well because the signal was being passed. If these jacks are used a lot
they can be bent a bit inside and not return to their normalled connections.
Not sure if this is your problem or not, but something to try.

--Tom

[mesaman]

I do not use the effects loop, so my problem isn't the same one you had. However, good advice on isolating the pre and power amps. I'll give that a shot and report back.

[mesaman]

I checked the power tubes via the FX loop - they seem to work. They are loud, but have less volume that the amp when functioning normally with preamp. This seems normal to me.

I get no sound out of the "slave out" which I think is a recording out. I also swapped tubes around to see if the problem was the phase inverter or some of the preliminary tubes in the preamp - no improvement.

Any ideas on the next most likely problem? I have basically babied this amp. I've played it mostly at living room levels and it is only in the past few months that I've been using it at gig volume on a regular basis. [finally got a band functioning :dude:]

[Dancing Frog]

Well, if you switched around all the preamp tubes and the power amp still works when going thru the F/X return, it's probably not the phase inverter or preamp tubes. The phase inverter is after the F/X loop. If you cycled every tube thru the PI position, something noticeably flaky should have happened with the power amp. Therefore, it's something deeper, maybe a blown capacitor in the preamp or in the power supply. Take it to the shop and don't mess around with it. The capacitors in amplifiers can store lethal amounts of current unless it's properly discharged by people who know how to do it safely.

Even if you baby it, components still wear out over time. It just the nature of the beast. Capacitors leak dielectric, solder joints break, resistors burn up, and wires corrode. Sometimes, just sitting in the basement doing nothing is enough to cause a malfunction.