TranMORGrifier Problem

[rocket88]

I swear this has become the story of my life. I get 3-5 great builds, then one where something is off that I can't figure out. I just built the TranMORGrifier and the only way I can describe it is that it just sounds like its farting. I followed the layout to the T, with 2 changes, a 100nF in place of the 10nF for the input cap, and I had to use a 20k linear pot in place of the 20k log as I ran out of 20k linear pots. I'm also using an Intersil CA3080e IC.

The output control works, but the ratio control seems to alter the output too, and I can't tell what the attack and release controls are doing since the only sound I get out of it is this farting sound.

I checked for solder bridges, checked the wiring, cuts, and double links, and the diode position, but it all seems good. I need some direction to figure out whats going on. I was thinking it could be the IC, so I tried another and I still have the same issue. I've checked the transistors to see if they are all good, and they test fine. So, now I'm lost.

Here are the Voltages I get.
IC
Pin 1: 0.000V                   Pin 8: 0.000V
Pin 2: 4.60V                     Pin 7: 9.33V
Pin 3: 4.60V                     Pin 6: 0.717V
Pin 4: 0.000V                   Pin 5: 0.662V

Q1               Q2                 Q3                Q4               Q5
E  0.010V      E 0.312V         C 9.03V         C 9.03V        C 9.33V
B  0.410V      B 0.111V         B 0.00V         B 0.00V        B 9.00V
C  9.33V       C 9.32V           E 0.00V         E 0.00V         E 8.15V

FYI: The readings on Q5 change when the attack and release pots are turned.

[rocket88]

Here are some pictures of the board top and bottom respectively.


FYI: some of the poly caps are physically larger or smaller, but are the correct values. They're just different versions of the Panasonic ECQ's.





As usual, thanks for any help you can give so I can get this working and finally have a compressor.

[Jopn]

Can you double check those voltages on Q5? I'm certainly no pro, but nearly 9v on all three legs looks fishy.

[rocket88]

Jopn, just double & triple checked and that's the correct voltage I get. I measured it by grounding the negative lead of my tester and using the positive lead at each leg. If I turn the ratio or attack knob the voltage at B changes for Q5, bot not a whole lot.

I'm no pro yet either, but I completely agree that something doesn't look right. I just cant figure it out.

The sad part is I was serious. I'll have a bunch of builds that go perfectly, or I catch any problem that happens. Then, I'll do something completely different and just hit a wall, and can't figure it out. After building a bunch of fuzzes I have no issues then the first overdrive I built, the first booster, the first Ge transistor build, first 1590a build, now my first compressor I hit a wall and something happens that I can't figure out. I try to systematically check for the problem following steps, and going on things that I've dealt with before, but I can't figure it out. It's driving me crazy.

[Silver Blues]

I know how you feel, man, the last compressor I tried to build didn't work for no apparent reason as well, and now my latest fuzz doesn't work and I have no idea why. It sucks  I wish I could help you.

[rocket88]

Thanks man. Right now I just put it aside to get some air and think. Hopefully someone who built it or has much more knowledge then me can help point me in the right direction. I would really hope that I don't have to take it all apart, and do a new board. I really don't want to loose more components.

[rocket88]

With a little help I was able to solve the problem. I accidentally added a 2.7k resistor in place of a 27k . I have to be more careful, but at least I got it up and running, and it sounds fan-freaking-tastic. John K was right, this is a great compressor for guitar and with a small mod for low end retention sounds excellent for bass too.