Lab5 Compressor issue

[nosaj]

i have a Lab5 that seems to be having a issue with the compressor not engaging. The way I understand it compressor rolled all the way to the left at -18 should be the most sensitive but it doesn't seem to matter any position of the compressor knob. it just doesn't work. Any help I can get would be greatly appreciated.
When powering on sometimes it will light for a sec then go off so the LED is good.
Thanks,
nosaj

[nosaj]

Any suggestions?

nosaj

[g1]

Comp. switch is good?
Looks to me like the CA3080 puts out a DC voltage that controls the gain of Q101 to compress. They have range of DC voltage at Q101 source shown (.5 to 2V), I think that should follow the pot setting.

[The Dude]

Make sure R185 & R186, the compressor adjust and trimmer, are good (maybe dirty?). Also make sure your input to the amp is high enough for you to drive the amp into compression.

[nosaj]

Ok will do. Found this doc and going to try tomorrow after checking switch and working r186.
Page 2 notes show setting compression.
nosaj
thanks again guys

[nosaj]

Cleaned both pots followed instructions for setting compression....nada nothing.
nosaj

[The Dude]

What are the voltages on A112 (the 4558 in the compressor circuit)? Is C139 good? Does the compressor LED light when you drive the amp hard and turn up the compression?

[nosaj]

Comp. switch is good?
Looks to me like the CA3080 puts out a DC voltage that controls the gain of Q101 to compress. They have range of DC voltage at Q101 source shown (.5 to 2V), I think that should follow the pot setting.

Well dang. i hooked up to c138 to measure the range of voltage from q101 and what do you know compression led lit up. So i had a cold joint .
Looks to working just fine now. Set the compression circuit and and now works as it should.

Hi's a Fives to everyone.
Thanks,
nosaj