Sunn Beta Lead Guitar Head major issues...

[inlifeindeath]

Hello all,

I'm having some issues with my Beta Lead head. Everything is powering up just fine, but the output on both channels is cutting out and very "fuzzy". Cranking the drive, level, and mids almost solves the solution, but it is still noticibly bad. I'd almost describe it as a guitar "raspberry". Any help is appreciated! Thanks.

Brad

[Gtr_tech]

could be just about anything from the front end to the pwr supply/output section. You'd need to go through it with a scope after verifying supply voltages are where they should be.

[Gaz]

try the amp debugging page to give you a lead:

Tube Amplifier Debugging Page

[Don Moose]

If you have another amp with an FX loop, try using the various sends and receives to see if you can isolate things to a particular section.

You know - Ch A send to other amp's return or other amp's send to master return - and take notes. What's left of my short-term memory means I have to triple-check things like this pretty often.

Hope this helps!

[Gtr_tech]

try the amp debugging page to give you a lead:

Tube Amplifier Debugging Page

Sunn Betas are SS amps.

[Don Moose]

As RG (and Enzo) often point out, the debug process is similar - the voltages are lower and the parts may look different, but a gain stage is a gain stage and an EQ section is an EQ section.

[gbono]

Sounds like one of the ouput transistors is damaged. There are also some socketed OP-amps that may be the issue. You can down load the service manual herehttp://sunn.ampage.org/site/svcmans/beta/

[Enzo]

Isolate the problem.

is it the power amp or the preamp? Or both? Are the power supply voltages up and clean?