Troubleshooting an Arp Sequencer

Jim Johnson jamos at
Sun May 10 08:45:45 CEST 1998

I'm trying to repair an Arp sequencer using minimal tools - no scope - and
I've run into something I can't understand.

This problem has to do with the Step circuit. When everything is assembled,
pressing the Step button causes the sequencer to advance, pretty
consistently, by 11 or 12 steps. However, when the jack panel board
containing the Step input jack is removed, it works correctly.

I removed that jack from the PC board, and the sequencer works fine. Put
the jack back in, same problem. I checked the jack out - it is loose in its
housing, but is not shorted.

Why should this be happening? Is it capacitance in the jack, or a leakage?

Also - when I opened this up, the backs of the jack panel boards were
covered with electrical tape, and after removing that there is a bunch of
adhesive on the board, not to mention amazing amounts of flux (which I
cleaned off). Is the tape stock, or added by some previous tech? 

Thanks - 

Jim Johnson 
Metaphoric Software
Makers of Techno Toys
Software for Electronic Music
info at

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