Problem experienced
1. A lot of distortion from circuit. Redused slightly by adjusting c2. lipping pot.
2. Heavy gating effect. No signal comes through unless the guitar is played vigorously. Notes die out very suddenly. Lighter playing can not be heard
Pictures
Drawn in red mark to indicate which corner is which on front/back pictures
Component side
Solder side
Layout
Schematic
Voltage Measurements
Supply voltage: 9.56
IC1
1: 0.16
2: 4.95
3: 4.95
4: 0
5: 0.19
6: 7.45
7: 9.56
8: 8.84
Q1
C: 7.03
B: 2.86
E: 2.50
Q2
C: 6.65
B: 7.40
E: 6.64
Q3
C: 9.49
B: 0
E: 0
Q4
C: 9.49
B: 0
E: 0
Q5
C: 9.52
B: 9.50
E: 8.93
Audio Probe
I've followed the signal from the input to the IC with a probe. The signal arrives relatively inscathed at pin 2 and 3 of the IC, but comes out terribly distorted at pin 6. Not sure where to go from here.
Part Substitutions
IC: CA3080
Transistors: 2n5088
Polarized 1µF caps are supposed to be tantalum. I've used electrolytic.
Unpolarized 1µF cap in the top left replaced by 100n ceramic. It was a polarized 1µF, but I canged it for the highest value non-polarized I had to see if it made a difference. It did not. The pictures are taken before this switch.
500K Reverse Log sustain pot replaced by 500K Linear.
150K Linear attack and clipping pots replaced by 100K for testing.
2K Trimmer should be "Set dead center". I am using a 25 turn 2K trimmer set to 1K.
Measures Taken
Double checked component placement. Found and corrected one error.
Double checked polarity of all the parts against datasheets for the components I used.
Replaced Q2. No difference measured.
Replaced IC. No difference measured.
Reflowed all solder joints.
Checked for solder bridges with DMM's continuity tester. None found.
Cried.
Wrote this post.
Additional information
I made one wrong cut. At pin 5 of IC1. Bent the pin and used extra solder to fix. DMM confirms continuity of the joint.
The socket for the IC is a 16pin socket cut in half, because I had no 8 pin IC's.
All parts substitutions made on the basis of availability at the time of building.
No attempt has been made to match transistors.
Really hoping someone can offer some advice on this. I am fairly inexperienced, and completely lost as for what to do next.
Keeley 4-knob compressor: Distorted and extremely gated
I have the same problem with my 5-knob modded Keeley build. everything seems fine but the sustain is very gated. Have you found the issue yet ?