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Doepfer

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Re: Troubleshooting A-155

2012-08-24 by Richard Horsman

Hi

It could be a problem with the jack socket below the pot instead of the pot
itself. I believe that when a lead is plugged into this the knob becomes an
attenuator of this signal. If the socket 'thinks' a cable is plugged in
then that knob may be attenuating zero volts so not doing anything. This
can happen when the metal contacts in the socket become damaged and touch
even when nothing is plugged in. You need to check continuity with a
multimeter, comparing the results with another working socket. Quite a
simple fix with a small screwdriver if this is the case.

Rich




Hi everyone!

I have got an A-155 sequencer where one of the pots on the bottom row does
not work. At all.

In order to try to pin down the error I have swapped the ICs from the top
row to the bottom row (http://www.doepfer.de/A100_pictures/doepfer_a155.jpg,
the two PCBs with the knobs), but the problem was still there. Is there
anything else I can do? I have also tried to measure resistance what is
happening when turning the pot, but I did not see anything that made the
offending pot differ from working pots.

Is the pot itself broken, or is there anything else I should try to pin
down the problem?

Modular regards,

Janne


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