Carvin BX600 Issue

BryanM · #1 08-28-2011, 04:58 PM

I have a Carvin BR610 combo that's been a trooper for the 4 years that I've owned it until just recently. The output from the power amp section seems to fluctuate and doesn't have much power but the DI/preamp section is working fine. I'm out of warranty on it so whatever repairs it needs will be done by me or an amp tech if I feel out of my league.

I've tried it with different speakers and the problem was consistent, tried my speakers with a different amp head and that was fine so it's not an issue with the speakers at all. The preamp section is getting constant power with no fluctuations in the signal so it's not the power supply. I have it narrowed to probably being an issue with the power amp section.

The crux of what caused the issue is that my band played a show last week and the PA amp that the club said they'd provide was broken, so the power amp section of the BX600 was used as an amp for the mains for a ~4 hour show. The signal chain was:

Mics and sources -> Yamaha MG1604 Mixer -> Effects Return on Carvin BX600 Amp -> 2 8 ohm Traynor 15" mains in parallel.

I'm planning on checking out if bridging the effects loop solves it so I know where to start there, since I've read that has been an issue on some Hartke and GK amps. Hopefully that solves it but if not, does anyone have any recommendations for where to start troubleshooting.

My thoughts are to isolate the power amp section and check for cold solders and loose joints, then check the connection across all of the resistors to see if any of them have burnt out, then move on to the other components.

**B-string** · #2 08-28-2011, 05:04 PM

Use some DeoxIT in the effects return jack. Best bet is the internal contacts of the return jack have fretting. Quick check; use an instrument cord from the effects send to effects return. If the trouble is gone the jack is dirty.

BryanM · #3 08-28-2011, 05:37 PM

Thanks for the quick response, that's what I planned on doing when I get home tonight and see if that does it. If it does I'll be very happy but if not I'll learn more about rebuilding amps than I know now.

craig.p · #4 08-28-2011, 06:53 PM

Open the amp and reseat several times every connector you can find, including any/all ribbon cables. Wait until you're in and then clean the effects return jack NC contacts.

The way you were using the amp sounds well within spec. Could be something just jarred loose inside.

BryanM · #5 08-29-2011, 04:42 PM

I think it was within spec but I'm worried if the mixer signal was too hot I burnt out the transformer. I had the compressor up above 50% just to be sure, but it did go into clipping a few times over the night when the other bands' vocalists couldn't keep from eating the mic.