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Old Crow's Synth Shop: Polysix KLM-367 Board Repair

WARNING: This repair section involves using a "Dremel" drilling tool to carefully bore out the PC board holes for parts and vias. Use the Dremel press accessory if you have it. Using the tool by hand tends to break drill bits.

Step 5: Preparing the Mounting Holes

5-1: Using a desoldering tool or fine-mesh "solder wick", remove the solder from each of the holes in which a replacement part of wire will mount. In the example, the holes marked with green and orange dots get this treatment. Be sure to do all of the desoldering from the bottom of the board, as shown. NOTE: the board is upside down and turned 180 degrees, so the board image and map image are now mirror-images of each other.

5-2: Clean the area with a brush and alcohol.

5-3: After the cleaning solution dries, place the board upside-down either under the chuck of a Dremel drill-press or other wise on a flat table with a telephone book underneath to protect the tabletop from the drill bit.

The Dremel is fitted with a #70 bit. These bits are tiny and easily broken if care is not taken. Proceed to carefully center the bit over a hole and bore out any remaining solder. At this time, tiny flecks of solder will "puff" out over the board; this will be cleaned up later. Make sure all drilling is done from the bottom side of the board. Here are closeups of the holes on this example's KLM-367 after drilling. (Note the one battery location solder pad that still has solder in it--this was done on purpose as the new battery holder only needs two mounting holes).

5-4: Clean both sides of the board with alcohol and brush to remove residual solder flecks. Be thorough.

Step 6: Fitting the New Parts and Wires

Scott Rider --