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Hello everyone.
I 've decided to give a try to fix this pedal. It's the Rev A and the schematics I attach seem more or less the same.
I hope somebody is familiar with the design.
The pedal gives proper signal, but in any setting it's like there is no effect.
I 've made some initial tests with my DMM, signal generator and oscilloscope.
The sound comes normal out of the out. It can be amplified by the volume pot.
There is continuity to every pin of every pot with the main board. No problem with the ribbons. Continuity is also good on all the parts of the PCB i've tested so far. The PCB seems really new.
The two spst switches seem to work fine.
I power the circuit with 18V DC.
All voltages are correct ( A+ , B+, C+) all around the test points. Haven't tested all ICs yet.
The speed and the intensity pots are dead. The volume pot works properly. The pots seem perfectly normal and all connections are like brand new. As I said before....Continuity is perfect.
I tried to connect the expression pedal with a TRS jack and there is some movement on the oscilloscope screen on pin 2 of U12, according to the change on the intensity pot. There is no change on the output signal. There is no signal on most Us. Only on the TL 072 op amps.
There is perfect signal , but absolutely without any movement (modulation) around all Qs (even on all 4 LDRs) , up to Q17 - Q18. These two show the same symptoms like U12 (it seems normal to me, since they are driving the op amp). Without a TRS there is no movements whatsoever.
The LFO lamp seems very unstable. Probably the problem, or the photoresistors?
I suspect something with the TRS of the expression pedal out or something with the H11F3 opto, or something with the VR1 led cell. Maybe I'm wrong.
It seems difficult and it's more difficult since I haven't got a numbered layout with the parts values. The pcb is a mess. If you could help it would be fantastic.
Thanks in advance.
I 've decided to give a try to fix this pedal. It's the Rev A and the schematics I attach seem more or less the same.
I hope somebody is familiar with the design.
The pedal gives proper signal, but in any setting it's like there is no effect.
I 've made some initial tests with my DMM, signal generator and oscilloscope.
The sound comes normal out of the out. It can be amplified by the volume pot.
There is continuity to every pin of every pot with the main board. No problem with the ribbons. Continuity is also good on all the parts of the PCB i've tested so far. The PCB seems really new.
The two spst switches seem to work fine.
I power the circuit with 18V DC.
All voltages are correct ( A+ , B+, C+) all around the test points. Haven't tested all ICs yet.
The speed and the intensity pots are dead. The volume pot works properly. The pots seem perfectly normal and all connections are like brand new. As I said before....Continuity is perfect.
I tried to connect the expression pedal with a TRS jack and there is some movement on the oscilloscope screen on pin 2 of U12, according to the change on the intensity pot. There is no change on the output signal. There is no signal on most Us. Only on the TL 072 op amps.
There is perfect signal , but absolutely without any movement (modulation) around all Qs (even on all 4 LDRs) , up to Q17 - Q18. These two show the same symptoms like U12 (it seems normal to me, since they are driving the op amp). Without a TRS there is no movements whatsoever.
The LFO lamp seems very unstable. Probably the problem, or the photoresistors?
I suspect something with the TRS of the expression pedal out or something with the H11F3 opto, or something with the VR1 led cell. Maybe I'm wrong.
It seems difficult and it's more difficult since I haven't got a numbered layout with the parts values. The pcb is a mess. If you could help it would be fantastic.
Thanks in advance.