This is a work in progress...
Many problems are due to cold solder joints, wrong components, wrong component polarity or simply broken components. A good thing to try before you tear everything apart is to get a magnifying glass and carefully inspect your work (under good lighting)
Here's a list of threads that might be useful in tracking down and solving some of your problems.
POWER
IC20 Getting very hot
J4 Voltage problems
J4 Voltage problems
J4 Voltage problems
J4 Voltage problems
J4 No Voltage
VCO
VCO Test Fails
Tuning knob not working
VCO no longer making sound
No SAW, only SQUARE
VCF
Filter warble
Filter Warble
Filter Warble
Filter Warble and dropouts
Troubleshooting VCF
ENV
Almost no env. decay control
Tuning problems
VCA
Output on both the mix and headphone jack is very low
HEADPHONE
Headphones out sometimes kills audio
Headphones stopped working
I/O BOARD
Main out very low and a little distorted
Midi In Problem
SEQUENCER
Tempo stuck at max bpm
Midi sync issue
LED brightness
Faulty buttons
Right way to burn firmware
Cant save any patterns
GENERAL PROBLEMS
Only accented notes playing
Knobs not acting quite right
MISCELANEOUS
BA6110 Voltages
pin / dc bias / ac signal
1 / 5.3v / 10mv
2 / 5.3v / 0mv
3 / 0.0v / 0mv
4 / 0.0v / 1.2v
5 / 0.0v / 0v
6 / 5.3v / 750mv
7 / 5.3v / 750mv
8 / 5.3v / 750mv
9 / 12v / 0v
LA4140 Voltages
set to random mode and volume full up
no headphones connected
pin1 1v offset 40mv of signal
pin2 3v offset 400mv of signal
pin3 3v offset 400mv of signal
pin4 3v offset 2v of signal
pin5 0v offset 0v of signal
pin6 3v offset 2v of signal
pin7 6v offset 0v of signal
pin8 6v offset 2v of signal
pin9 3v offset 0v of signal
these values are approximate
variations of 10% should be expected
Truth Table for the greyhill 16 position rotary switches
OBSOLETE LINKS
Actual cost thread (international duty & tariff)
BA6110 "420 178" bad batch
Updated 2019-06-11 to update some forums URLs. No content changes.
TROUBLESHOOTING FAQ
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Please be positive and constructive with your questions and comments.
Please be positive and constructive with your questions and comments.