Ampeg B2RE problems

[iammike.music]

Hi all, this is my first post; so far I'm loving this forum!

I have an Ampeg B2RE that I got off of CL and it cuts out (decreased volume and very scratchy) when it's on a circuit with other amplifiers.

I understand that bass amplifiers are generally the first to feel the effects of the circuit voltage dropping, but I've got several other bass amps that perform perfectly under the same conditions.

Does anyone have any knowledge of the B2RE; like if this is a common problem with this model, or any ideas on where to start with repairing the amp?

I've contacted Ampeg customer support, but there was no real help there. And since this is a new amp I'm not too hopeful on getting a schematic, but any advice would be greatly appreciated!

[Enzo]

Where to start? Sure. Isolate the problem. Under failure conditions, connect a spare cord from the preamp out jack to the power amp in jack. ANy help?

If not, then connect a test signal - the guitar will do - to the power amp in jack. How does the power amp sound? Likewise plug the guitar into the front, run a line from the preamp out to another amp and speaker, and see how the preamp sounds. Seems unlikely both preamp and power amp have the same thing wrong.

Monitor the working power rails in teh amp. DO they go funny? I can't imagine why the amp would act up just by sharing the mains with another amp. Unless they are connected together and there is a ground loop.

If you send me an email to:
tmenzo at msn dot com
with Ampeg B2RE schematic as the subjet line, and ask for them, I will send the drawings.

[iammike.music]

Ok, here's where I am now.

Under failure conditions the preamp out functions just fine, the power amp in does not; so the malfunction is in the power section just as suspected.

With the other amplifiers turned on and working the wall outlet voltage is steady at 120 V.

I have not measured the voltages at the test points shown on the schematic while under failure conditions, but they measure normal when the amp is the only device operating.

While the amp is under failure the limiter light flashes very quickly as if the limiter is being tripped constantly and a buzz can be heard when another guitar amplifier is being played.

Is is possible that the guitar amplifiers are injecting noise into the circuit such that the B2RE is recieving a very noisy 120V?

I'm thinking I might try using an isolation transformer to see if I can filter the power to the B2RE a little more.

Any other suggestions?

Thanks so much for the schematic, it's been a huge help!

[mikemcnj]

I played last weekend and had the exact same issues. I was wondering if you had any success in fixing your problem. I was considering adding a power conditioner to the setup to see if that helps. I can't believe the issue has not happened to others as well, unless we really had a bad electrical set up at the gig.

Mike Mc.

[Mark Black]

Regardless of anything else those amps have a very common problem of solder cracks at the multipin connector headers, as well as at other places.

That stuff needs to be dealt with, even if it turns out not to be THE problem.