Marshall AVT150H losing power in OD2 channel

[hamahakki]

Hi

I have an AVT150H that I use live and lately it's be giving me problems. I use the 4 individual channel volumes to balance my sound for channel switching, then just tweak the master volume to suit the room, or if micing my cab.

Over the last month or so I have experienced a sever power drain in my OD 2 channel so now I have maxed out that volume setting and it is still about 50 % weaker than my other channels. I've had someone check the amp out and they couldn't find anything wrong with it.

Anyone seen this problem before??

[Enzo]

Look at the output pins of hte op amps in that channel. If any show DC offset voltage on the output pin, replace it.

[hamahakki]

Hey Enzo

thanks for the tip. The op amps - are those the infamous TDA7293's or something else?

I'm going to replace those and switch out the fan and see if that fixes the problem. I'll post again when I have some results (good or bad!!).

[Enzo]

No, the 7293s are you power amps, they are not in the preamp. Your op amps are types like 4558,4560,4580, TL072, etc. On the AVT series, I think they are mainly in SIPs rather than DIPs. They would be on the front panel board.

Your power amps have nothing to do with a preamp problem. They have no way of knowing which channel you are using.