Guyatone VT3 tremolo repair - schema., voltages, need help

[yeeshkul]

Hey guys i have Guayatone VT3 tremolo for repair. If there is any output signal then it is barely audible.
I've never dealt with any tremolo, but the schematics show this:

Oscillator signal and buffered dry input signal mixed together, then buffered again and led through the output opamp out of the circuit.

All the voltages measured are at the picture(fed by wallwart 9.1V):



I checked the circuit by audio probe and the signal seems to die right after the first OA (mixer?).
I checked the oscillator signal by audio probe and it seems to be ok.
Both pots seem to be ok.
The oscillator ground and the circuit ground are not connected on the picture which is probably a mistake.

There are 3 chips in the circuit:
1. input buffer + output amp M5218 (dual)
2. oscillator TL022
3. mixing opamp - it is dual but only one half is used LM308

can anyone help please?

[yeeshkul]

The both switching FETs are all right.  I suspect the LM308 although the voltages seem to be normal.
Guys would you recommend any replacement for LM308? LM386?

[jrc4558]

It's an OTA LM3080 N, not the OpAmp LM308. Find the proper part, otherwise the replacement will not work.
Good luck!

[yeeshkul]

Haha, now i see I was looking at the LM308 datasheet and it states "NC" for the pin 5. That quite confused me .