Joe Meek VC3Q Repair Advice

[turbo605]

My Joe Meek VC3Q started generating unsolicited ouput pulses. Frequency is about 2 times per second. The dB LED bargraph pulses to the rail. The pulses are agravated whenever the 48V phantom power is on. The pulses slow down or stop whenever the CdS photocell in the compressor is covered (light is blocked). The power bus +/- supply looks OK and is not pulsing. I suspect an issue with the compressor circuit (maybe a bad LM324 or possibly a leaky aluminum capacitor).

Anyone else experience this problem? Does anyone have access to a schematic for the VC3Q?

Thanks in advance.
Bill
majormindup@gmail.com

 

[moresound]

Bill .... Are you using the original provided power supply?

 

[turbo605]

I'm using the correct wall wart (12 vrms @ 830mA). I believe this is the original unit. The unloaded wall wart output measures 14.9 vrms. Additionally, the the IC voltages measure +/- 12 VDC with no sign of ripple or pulsing. So I've dismissed the power supply as the problem. I was able to get a schematic for the VC3Q but it is not correct. I've done some reverse engineering of the compressor circuit but have not yet done the EQ circuit. This will probably take too much time.

Bottom line - I'm seriously thinking of designing my own channel strip (preamp / optical compressor). Since manufacturers will not disclose schematics for repair /troubleshooting, that seems to be the only viable solution - build your own. Anyone want to participate?