Author Topic: I have a problem with a mixer  (Read 855 times)


  • Transistor Tickler
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I have a problem with a mixer
« on: October 07, 2019, 12:07:16 PM »
Hi all,
I have a Mackie 402-VLZ3 since about 10 years.
It's a nice toy, I use it with computer out, in, instruments and other stuff that make noise.
Mic channels also have the instrument switch, a buffer that allow me to play with my passive bass directly into the mixer.
The switch stopped to work, when I activate it no sound come out.

the buffers are the 2 opamps of a TL072.
this is the schematic (I attached the complete pdf file):

I measured the voltages:
1. -15.04
2. -15.04
3. -1.87
4. -16.30
5. -1.87
6. -14.96
7. -14.96
8. 16.05

I also tried to probe the output of the opamps and are both mute.
Maybe the tl02 died?

Thanks a lot.

PS. I don't know if this is the correct section, but this is not DIY, so...
PPS. Sorry for bad english. Any errors are google translate's fault  ;D


  • Electron Doctor
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Re: I have a problem with a mixer
« Reply #1 on: October 10, 2019, 05:28:52 AM »
Looks dead to me.
Works at Lectric-FX