Digitech 2101 compressor

[Jmpj50]

Hello I was wanting to see if somebody could tell me how this compressor works in the 2101 . It doesn’t work only in bypass. If I turn it on it turns off all the sound. I was doing the compressor setup from tube tester sight you should be able to turn p2 trimmer until you get 0vdc or +or- 30mV on pin 1 of u9a. All I get is around 9vdc. So I changed p2 trimmer and u9a with new ones hoping that would fix it that didn’t do anything. If someone could look at the schematic tell what causing we’re I can’t adjust p2 trimmer or something else on the schematic I should be looking at. We’re I can fix it and get it working. The compressor schematic in the one in the middle

[The Dude]

I wouldn't have started out twittling with trim pots. That said, if you have a scope, trace signal through the unit. If no scope, use a DVM set to AC volts. Either way, inject a signal and follow it through the circuit to see where you lose the signal. Before that, start with your power supply and make sure all voltages are present.

[Jon Snell]

It uses the bit stream convertor chip, SAA7360, to convert analogue into digital. This is fed into the digital compressor and the preset P1 sets to null point.
The compressor is controlled by the pulses on pins 6 & 7 of the compressor.
The output is sent through an AD2861, A-D convertor, cleaned up through a couple of op amps and that is how it works.

[Jmpj50]

Ok thanks for the info

[g1]

Hello I was wanting to see if somebody could tell me how this compressor works in the 2101 . It doesn’t work only in bypass. If I turn it on it turns off all the sound. I was doing the compressor setup from tube tester sight you should be able to turn p2 trimmer until you get 0vdc or +or- 30mV on pin 1 of u9a. All I get is around 9vdc.

I guess you mean this site: http://www.tube-tester.com/sites/gsp...tm#compression

Was the 2101 working ok before you adjusted P2 ? What happens if you set P2 back to the approximate setting it was at before you adjusted it?
Does U9 have it's proper supply voltages at pins 4 and 8 ? (- and + 12V)

[Jmpj50]

I bought 2101 about a month ago I put new tubes in it. I was setting up a new patch I went to turn the compressor on the sound cut off. Then I bypassed the compressor it started working again. So everything thing works fine accept the compressor. No the compressor wasn’t working before I tried the compressor setup from tube tester sight. Actually p2 doesn’t do anything when I turn it. It has 12 volt coming into p2. And u9 has the correct voltage coming in. This is crazy I was wondering if the dbx chip has gone bad.

[g1]

Actually p2 doesn’t do anything when I turn it. It has 12 volt coming into p2. And u9 has the correct voltage coming in. This is crazy I was wondering if the dbx chip has gone bad.

P2 needs to have +12 and -12V into it. Check they are both there. And check that you can get 0V at U9 pin2 by adjusting P2.

[Jmpj50]

Ok I’ll check

[drewl]

Did you check if the compressor levels are turned down?

I replaced the battery on an ADA preamp and along with erasing the presets, all levels were at zero, so no sound until I set up new patches.

[Jmpj50]

Ok I did some checking I’m not getting 12 v at p2. it’s like 1.4 v. I’m getting 9 v at pin 7 of u62. So that’s sending 9v up to pin2 of u9a. And p2 won’t do anything turning it.

[g1]

I’m getting 9 v at pin 7 of u62.

Does U62 have it's minus 12V at pin4 ? And pin5 good connection to ground? If both are good I would try replacing it.

[Jmpj50]

Replace u62?

[g1]

Yes, U62 is the one I meant. What is the DC volts on it's pins 5 & 6 ?

[Jmpj50]

Ok pin 6 is 11.14 v pin 5 is like 000.4mv

[g1]

You have not said whether you found the proper minus 12V on pin4, and also at one end of R122.