Sunn Beta Lead Issues

[cptdaisy]

So I don't know too much technical amp info, but I was playing my Beta Lead Combo and the sound suddenly went out. Lately it had been sounding more overdriven. Now when I play, the sound only comes out if I strum hard or if the gain is really loud, like some HPF is out of wack.

I really didn't know where else to turn. Would hate to loose this loyal amp.

[MammothVolume]

Give it a wrap on the top... These are known to vibrate themselves to death, especially in combo form... Did the LED channel indicators go out? Hope not, that chip is difficult to find...

[theJJ]

Hi CPTDAISY:

Your problem sounds similar to one I had with my Beta Lead.  When the power output drops, does it also get kinda "crunchy?"  Mine did. (See my earlier thread: "Sunn Beta Lead Problem" from last year)

I tried the suggestions on here--isolating pre-amp/amp circuits, cleaning circuit boards, checking solder joints, etc.--but could NOT get it to work.  Its worth taking a look for the easy fix.  Obviously BE CAREFUL when working on electronic circuits--capacitors can still hold a lethal charge, even when the power is off!

Ultimately the problem on mine was beyond my admittedly-limited expertise in amp circuits.  I found a nearby electronics place that works on vintage music gear.  They diagnosed the problem--it WAS in one of the amp circuits--got the parts and got it fixed for under $150.

Good Luck!

JJ

[GMFx]

Did the LED channel indicators go out? Hope not, that chip is difficult to find...

are both connected or is it possible that only one goes out and what could that indicate?

[loudthud]

On a Beta I found at a music store, none of the LEDs would come on and there was no sound from the amp, even through the Power Amp input on the back. The -15V power supply was bad. That chip that controls the LEDs is hard to find but it only takes two chips to replace it. They don't go bad that often. When they do, you can still get sound from the Power Amp input on the back.

[cptdaisy]

So, I was playing drums in my band for a while and I've been putting off this problem.

The sound is extremely distorted when played, and it is very similar, it seems, to your issue JJ. The LEDs stay on no matter what. But the real issue is that the sound will cut off after it gets below a certain volume. if I strum hard it will stay for about 2 seconds before going on-and-off and then staying off. Seems like serious circuitry am I right?