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