Behringer pmp3000 channel problem

[bigdrums925]

The mixer is not passing signal from either input to any part of the tone or aux section and not lighting clip or signal present LED's. Comparing to adjacent channels I see discrepancies where no signal is present at the 1/4" input when injected on canon jack. When signal is injected on the 1/4" jack, no signal is present further down the path. Have checked all the components in the area and all seem OK. Hopefully someone here has had this problem before and can steer me to the problem.
Thanks

[The Dude]

The schematic is available here if you don't already have it.

https://www.electronica-pt.com/esque...pmp3000-16040/

Most commonly, one or more of the transistors right off the input are shorted, but it's not a fix-all. You'll have to check them.

[bigdrums925]

I got the schematic and followed the signal into T13 channel 7 which is T1 channel 1 on the schematic. Comparing channel 7 to channel 8, I find the signal is equal on the base of T13 and T15 (channel 8). Yet there is no output from T13 like there is on T15. So change the transistor of course and still nothing. BTW both the T13 transistors test good. Now what? I'm stumped

[The Dude]

What are the voltages on T13 and T34?

[The Dude]

Just uploading the pertinent part of the schematic in case anyone wants to play along. The entire schematic is too large to upload.

PMH3000 Input Ch7+8.pdf

[bigdrums925]

T13: b 0.0 c -6.3 e -6.9
T34 b -5.5 c -4.8 e -6.2

I don't know why the collector of T13 is different from the base of T34?

[The Dude]

There are some issues there. (First) I think you have the basing diagram wrong for your readings. Look up the datasheet to be sure. (Second) Collector of T13 and Base of T34 are the same point. Emitter of T13 is the same point as Collector of T34. So, something isn't jiving. You also might have burnt traces or connection issues, so check continuity for C-T13 = B-T34 and E-T13 = C-T34.

Edit: You can also compare those voltages to the working channel right next to it and see what voltages should be.

[bigdrums925]

My bad
R58 (and all the similar resistors) have 15v feeding into them. But R58 bottom shows -7.8v where all the others are .6v?

[The Dude]

Check T14 and T35.

[bigdrums925]

T14 & T35 both test good. What else might cause bottom of R58 and T34 collector to be -7.8v?

[Enzo]

Open resistor?

R58 does not connect to T34.