Am 01.03.2018 um 15:20 schrieb
jimpster@me.com [PolySix]:
> So, I'm still none the wiser with the clone board. Filter is always
> modulating no matter where I set the MG switch.
Check the pins 1, 11, and 12 of IC29 while changing the switch
positions. They should change from 0 to 5V when the switch changes its
position.
If No: check whether the switch itself with a scope, In two of its
positions it should read the signal of CPU ports P12 and P11.
Possibly missing P11/12 signal or dirty in the switch
If Yes:
check whether the signal of thos three pins reaches the LM339 at pins 9,
11, and 5
If no: cold solder joint or pcb trace broken
If yes:
check whether the pis 14,13, and 2 change with changing the switch?
If No: do pins 8,10,4 read 2,5V?
If no: cold solder joint or pcb trace broken
If Yes: -> LM339 dead
If Yes:
Check whther the signals reach pins 5,13,12 of IC 1 (4066)
If no: cold solder joint or pcb trace broken
If Yes: 4066 broken.
--
http://www.florian-anwander.de