VerreyckenGerd wrote:Thanks for the help man, but the problem is not the vco my scope measures both waveforms perfectly until the selected waveform passes R62. After R62 (filterside) there is only 8V constant. Is the waveform converted to a variable current waveform with constant voltage or something
The important thing is to measure everything in the filter part with an AC coupled scope. The voltages are very small but travel on top of a significant DC bias (we're talking signal voltages under 100mV).
The 8V DC are ok but you need to check the AC part on top of it. Then trace it through the filter ladder, measuring C18, C19, C24, C26. The signal will get progressively weaker through the ladder (and softer, depending on the position of the cutoff control). You may also want to measure the DC offset on those caps.