I know you said you built a new power supply. And, I don't believe this unit contains any VCA's? So perhaps, your new supply is slightly underrated? You may also have swapped out some capacitors in the wrong polarity?

You need posted on this project
Ms. Remy Ann David

Recheck your soldered joints that you did. Check ALL soldered joints and
connections.
Clean all pots and faders, if possible.
Clean all socketed joints, and ensure that they mate securely.
Clean all input/output jacks. Check all switches, and clean, if possible.

There also may be certain places you can inject a signal to see if it happens before or after that stage, while eliminating earlier or later stages. Like, INTO a submix or master bus, or direct OUT OF channels, etc. If you've bypassed earlier stages, and it still happens, you know the problem is in or after the injection stage. If it DOESN'T still happen, it's before that stage.

Could be one or more bad/dirty pot, fader, switch, connector, or switching jack. Could be bad solder joint or loose connection. Might as well clean and tidy up as much as possible while it's open, anyway. Could be a wrong value or incorrectly installed component. Could be a bad component on the circuitboard.

If none of that works, you'll have to run a signal through, and follow the schematic to see where it bugs out at.

Check all of above.

Kapt.Krunch

thanks for the replies,

when i first plugged in my power supply i did have one of the electro caps backwards, but i realized pretty soon when the room filled with stinky smoke. but i have replaced that and it seems fine now.

i am pretty sure that the power supply is supplying the correct voltage, because the +- 15v on the circuit diagram corresponds with writing on some of the circuits inside. i think i will have to do as kapt crunch suggested and go through and clean and check everything and all the soldering joints, and maybe get a new mixer. i think this one has been through its fair share of modifications. it was once a 24-4-2, but at some stage it was cut in half and made into a 12-4-2. so there are several foreign circuits inside and odd patch leads that obviously weren't part of the original mixer.

thanks again for the advice

mike

If it was a 16 x 4 x 2 and it was cut in half, your math is bad. That's eight, not 12. There's your first problem. And no, Enzyte will not make your penis grow larger unless you look closer at it. Maybe a circus mirror will help? So if somebody hacksawed a mixer in half, I hope you didn't offer them more than $25? You purchased something already pre-screwed, pre-broken, pre-stupid, pre-fooled. What were you pre-thinking about? Now that you're post thinking?

So really, with the thing powered up, you have to start injecting a known signal source such as a CD player, into and out of every stage, throughout the device. It would actually be preferable to have a signal oscillator & volt meter for steady-state measurements. Active, dynamic music as a signal source already has changes in volume and so is hard to use as a reference. But chances are, you don't have a tone generator nor volt meter?

Sorry you can't six stupid.
Ms. Remy Ann David

Sounds like a power supply issue to me. Have you checked all the voltages under load?