ARP Omni 2 Repair

I received an ARP Omni 2 “for parts” that literally was in parts!  It came to me as a pile of boards.

ARP Omni 2 Heap Of Parts

ARP Omni 2 Heap Of Parts

Since it was complete, I decided to restore it slowly as time permits, recapping each board, inspecting for damage, etc…  This morning I got around to the Upper Voicing Board.  Someone had tried to fix a problem (likely a “stuck” note, caused by a shorted tantalum capacitor), but they lifted some solder pads and destroyed a trace while changing some diodes.

ARP Omni 2 Upper Voicing Board Before

ARP Omni 2 Upper Voicing Board Before

To correct the damaged trace between the diode and the resistor network, they soldered a 1W resistor to the board…  ARP PCBs are extremely easy to damage without proper soldering techniques.  They are not plated through hole, so it’s easy to lift solder pads, and more difficult to solder a component with traces on the component side of the board.  With some flux, and good soldering and desoldering skills, it is possible to work on these delicate ARP boards and have them looking pro when you’re done with them.

ARP Omni 2 Upper Voicing Board After

ARP Omni 2 Upper Voicing Board After

Here’s the same board with the 1W resistor hack removed, the board recapped (using the Synthchaser capacitor kit–pardon the shameless self promotion), and the diodes the previous person tinkered with also replaced.  Notice on the capacitors the smooth solder fillets on the component side of the board.  Because the boards aren’t plated through hole, it’s important that the solder joints on both sides of the board be solid!

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