help w/ peavey TNT 150

[pontiacpete]

This amp has a scratchy post pot. I replaced the pot and swapped out all the electrolytics in the area and the nearest IC, checked resistors and changed the one .1uf cap closer to the input. At the moment I don't have a schematic, but I hope to have it by tomorrow morning. ON one leg of the pot there is -.474v and it varies as the pot is turned. On a light limiter the light jumps up brighter as the pot is turned.

Does anyone have any advice?
Thanks in advance.
pete

[pontiacpete]

Here's the schematic. I've swapped out these parts so far U2,U3,R44,C24,C26 C1 and C14.

[52 Bill]

How about U10?
Trace the voltage on the pot back to where it originates from, like U10. It should be fairly simple to follow the signal path until you find where the voltage is highest, and where it shouldn't be.

[pontiacpete]

I changed the regulators vr1/2. Now it is running -/+15v, don't know why it isn't -/+16v. But it'ssStill scratchy. I trace this neg voltage to the neg side of C26 and the same voltage to R49. ON the other side of r49 there's -2.5v which is the same as that on U9B pin5 and 6. PIn 7 of U10B has -10v. Should there be -10v on pin7 of U10? Should there be negative voltage on pin5 and 6 of U9? I swapped out each of these IC, and the resistors seem to being what they're suppose to be doing, dropping voltage.
Is it possible that it's ok to have negative voltage on a pot? Could the new pots that I've put in, possibly be bad?
I'm stumped.

[pontiacpete]

Thanks for the help Bill52, I found a broken trace were R65, the crossover freq pot, was installed.