TROUBLESHOOTING FAQ

by phono on Sat May 24, 2008 9:01 am

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

Image

OBSOLETE LINKS
Actual cost thread (international duty & tariff)
BA6110 "420 178" bad batch
Image
x0x #733 Image SH-101 MC-202 TB-303 TR-606 TR-808 TR-909 MKS-50 Juno-106 A-100 Virus-B E-6400 SX-150 Monotron
User avatar
phono
 
Posts: 1502
Joined: Wed May 02, 2007 3:01 pm
Location: forum whore aka 2Cv