fender studio lead amp-chnl 1 low gain

[Mars Amp Repair]

Guys,
I just finished repairing a Studio Live. It had all the typical bad connections as well as a noisey offset trim pot that ran me around in circles for a while (the offset vr is on the chnl 1/2 switching IC...anyone know what it's for? The IC is a 4001 & I haven't had the chance to look it up.

Anyway, I've only seen one other of these amps & I don't recall how the other one reacted. Perhaps someone with more experience with these amps can tell me if it is typical for channel one to have much less gain than channel 2.

I can turn channel 1 all the way up & it's just not as loud as I would expect. Channel 2 being the gain/distortion channel, gets really loud as expected.

I don't suspect anything is really wrong with it, but can't be for sure. Fortunately this is a new amp to the owner he only plays it low at home, so he's not concerned.

Anyone know for sure? thanx, glen

[Enzo]

It is a 4007, a 4001 makes no sense there.

The 4007 is just a CMOS logic IC, but inside it is three simple push pull xstr pairs. In this case the three are wired in parallel. It is running single supply, and off a neg rail at that. SO the positive pins of the chip go to ground and the negative to -6.2v set by D7. SO 6v across the chip.

Note signal path in and out is cap isolated. So with only 6v to play with, you need to center the zero point right in the middle. That is what the trim pot is for. Set TP1 for half of whatever appears on TP2.

it is just an amplifier stage. What it does different, I could not tell you Perhaps it overdrives different from simple clipping.