Compressor Troubleshooting

[cnspedalbuilder]

Hello, I am seeking advice on troubleshooting the Aion Aurora compressor that I built. I previously posted about the IC on this compressor build, but it turns out that the IC is probably not the problem and after that the thread went dead (though @PRR made helpful suggestions). I hope it's not bad form to start a new thread, but since this is a more general troubleshooting question it seemed ok.

I feel silly that I have not yet figured it out yet. I dont need anyone to solve for me, just point me in the right direction on what to check out. If you just think I should desolder whatever I can (the IC and transistor sockets will be very difficult) and start over, so be it.

Here is my issue:



• I have built the Aion MXR/JangleBox compressor clone https://aionelectronics.com/project/aurora-ross-dyna-compressor/
• I initially made some component substitutions, but it is now close to the original MXR instructions (except for the tone switch capacitors)
• Build docs are here: https://www.dropbox.com/s/d7m5f9rbe6d68f2/aion-aurora-ross-compressor-documentation.pdf?dl=1
• I get sound on bypass, but no sound comes when pedal is on.
• If I touch a jumper on pins 2 or 3 on the OpAmp (CA3080 IC) with other side on the PCB output solder pad, I get the clean sound. So, it's not a switch issue, and that means at least the signal path is making it to the 3080.
• Here are my current voltages:
  IC (pins 2-7): 4.91, 4.91, 0, 8.64, 2.67, 9.49  [yes pin 5 is way too high and pin 6 is probably low]
  Q1: 7.7, 2.2, 1.81
  Q2: 7.38, 2.68, 2.09
  Q3: 0, 2, 9.4
  Q4: 0, .6mV? [DMM kept flitting around a few millivolts], 9.44
  Q5: 9.49, 9.43, 9
  (Please note that the transistor labels for the Aion DO NOT match the Ross/MXR schematics.)
• I get the high voltage reading on IC pin 5 even if there is no IC in the socket. I am not sure if this means I am measuring voltages wrong or if it is to be expected. 
• It's not the CA3080 chip. I got the original from SmallBear and Steve sent me two more when I said I had a problem. I got the same readings from the new one he sent (I'm saving the third in case I'm somehow blowing out the IC at pin 5
  

From going over the schematic many times, my guess is that something is wrong in the part of the circuit that connects with pin 5 (regulating the bias current to the IC?).   

I am stumped and I feel stupid because after building from vero, this pedal should have been easy for me. If I'm making a dumb mistake or writing stuff that makes no sense, call me on it, better to swallow pride and learn. Any ideas are greatly appreciated. Thank you.

[banjerpickin]

Don't know if you ever found a solution to this, but I am having the same exact problem and have gotten some people interested on my thread, might be able to help you out:

http://www.diystompboxes.com/smfforum/index.php?topic=116021.msg1073078#msg1073078

[cnspedalbuilder]

Thank you, I had given up until I found your msg. I will take a look at your thread and see what I might have missed.

I'll say one thing--that PCB is not very forgiving. It is really thick, so desoldering and getting components out is a nightmare. My board started out white, now it's brown!

[banjerpickin]

Thank you, I had given up until I found your msg. I will take a look at your thread and see what I might have missed.

I'll say one thing--that PCB is not very forgiving. It is really thick, so desoldering and getting components out is a nightmare. My board started out white, now it's brown!

Yes I definitely had to clean mine with some rubbing alcohol by the time I was done to get rid of the brown  .  My issue ended up being as simple as a bad cap, can't recommend the audio probe approach enough.  Good luck!

[Kipper4]

Your IC pin 6 looks way too high.
Shouldnt it be around 0.6v?

Double check your voltages against those posted in the thread Banjerpickin linked to.

remember as you say the q1 q2 etc might be numbered different to the Ross though.