Ampeg B2R lost a lot of power

[Jeebus666]

Hi!
My Ampeg B2R was just fine couple of weeks ago, when we rehearsed the last time. Yesterday I went to play a little bit with it and I realized that the amp just didn't give me the same power that it used to. Before this the "band volume" with my amp was to set the master volume knob around 10 o'clock, now I had to crank it all the way up and still it sounds too low.

Other than the power loss, the amp seems to be working normally (EQ etc.). I've tried it with other basses, cabs, cables and all. Also I tried the same set up with my friends Hartke head (which has about the half of the power that my Ampeg has), which sounded a lot louder and beated the Ampeg's power (with the master on full) easily.

So, I opened the head ja detached the circuit board. The solderings look normal and the components doesn't have any visible damages.

I already asked the same question in TalkBass -forum and there was couple of people who had similiar problems. Here's the link to my post: http://www.talkbass.com/forum/showthread.php?t=499014

So, what should I do? Any suggestions? Right now I don't have a scope, but I'm going to get one as soon as possible.

[drewl]

I had one this week that did the same thing.
Power would intermittantly drop and it would get distorted.
This one had a few bad solder joint problems.
It's got a few cement power resistors that drop the voltage for the IC's that heat up and loose connection and it also had an opamp that had bad solder connections.
Try cleaning the fx loop jacks and make sure they're soldered well also.

[bezmotivnik]

Judging from that thread, there's a positive epidemic of loss of output strength with no other symptoms on these Ampeg solid-state amps. I'd be extremely interested in seeing the solution.

If this is as common as it appears to be, any Ampeg service tech ought to know exactly what's up.

Here's hoping!

[Jeebus666]

Try cleaning the fx loop jacks and make sure they're soldered well also.

The loop jacks are clean and all the solder joints of the amp are looking good. The tone is normal (no difference in eq etc.). Here's the TalkBass thread: http://www.talkbass.com/forum/showthread.php?t=499014

[drewl]

Okay, try and isolate the problem to the preamp or poweramp.
See if you have the correct output at the fx send jacks, then try putting a signal into the fx return jacks to see if the power amp is okay.

[Jeebus666]

I tested it: the problem is in the poweramp.

[Jeebus666]

Oh, dear god or whatsoever. The problem is solved at least for now. I checked and re-soldered all the bias resistors and the amp came back to life. Lets see how long it lasts!