Sunn Beta Lead Problem

[tunemeister]

Hi,
I have a beta Lead 2x12 which I bought 2nd hand back in 82. In general it has been very reliable but on the couple of occassions that it has gone down it  has been when I have used the footswitch.

First time this happened I trod on the button to change channel & one channel went down. I had it repaired & the tech said he had replaced 2 of the transistors with ICs & this should stop it recurring. Amp has been fine for about 10 years, just intermittent use, but yesterday trod on the reverb button & channel A went bang. B still works but no footswitching, wondered if anyone else has had similar problem or can point mt in the right direction?

I know 2 repairs in 24 years is good going but it is always worth checking the knowledge out there.

[JoeArthur]

Hi,
I have a beta Lead 2x12 which I bought 2nd hand back in 82. In general it has been very reliable but on the couple of occassions that it has gone down it  has been when I have used the footswitch.

First time this happened I trod on the button to change channel & one channel went down. I had it repaired & the tech said he had replaced 2 of the transistors with ICs & this should stop it recurring. Amp has been fine for about 10 years, just intermittent use, but yesterday trod on the reverb button & channel A went bang. B still works but no footswitching, wondered if anyone else has had similar problem or can point mt in the right direction?

I know 2 repairs in 24 years is good going but it is always worth checking the knowledge out there.

This doesn't sound right at all.

The only transistors used for switching are the ones that drive the opamps and the indicator lights on the front panel.  That opamp does drive a pair of FET's, but I don't see where replacing either the transistor or FETs with an opamp would be a suitable or even possible repair.

The reverb footswitching is no different than 99.999 percent of the amps out there - the output from the reverb recovery amp is simply grounded to kill the reverb signal.  This footswitching has no circuit connection with the channel switching.  One cannot affect the other... unless...

I don't have a footswitch for my betalead.  I know it is a weird 4 connector screw on type of thing.  Is it possible that you got it plugged in wrong?  I would first disconnect it and then see if both channel LEDs light up when you plug into the both input.