Dear members,

Technically I am so far with electronics, so I thought maybe you can help with this strange problem with my favorite filter A-108.

I don't hear any any sound from the outputs, while the input is connected to the Saw of A-111; no click, no tick, no noise, just 100% silence, as if my whole setup is off. As if I'm on the top of Mount Everest.

Some time ago, when replacing some modules, I touched a place on solder side near the Frequency potentio meter with the screwdriver, while the system was on. At once heavy agressive sparks rapidly appeared [not expected from such a 12V board], almost hit my face.

The Frequency potentio meter was damaged and totally out of work. I only could change the frequency via the control voltage inputs. For the rest everything was fine.

But since I took the damaged Frequency potentio meter out, I don't hear any sound anymore. It's 100% silence. The same after putting a new one.

I did some measuring with these settings:

With Sawtooth,

A-111 Octave Switch at 0 (zero),

A-108 Input Volume at 5,

No CV's

Results:

From the power supply:

-12V and +12V

And the chips also get their power.

From the input:

DC = changing from -1V to +1V

AC = 1.6V

From CA3083Z: from IC4:

pin1 (input) = 1V

pin16 (input) = 1,5V

pin15 (output) = 0,5V

From TL084:

All the inputs of their own circuits where equal. Sometimes the outputs where the same as their inputs.

From BC 547:

Q1 = 0,70

Q2 = 0,69

From the Outputs of the A-108: with DC measurement:

6db = 0,30V

12db = 0,15V

24db = 0,31V

48db = 0,06V

BP = 0,09V

From the Outputs of the A-108: with AC measurement:

All Outputs = 0V