I just replaced the M5230 in a Polysix that was blowing fuses under full load. With all the other boards powered up except the KLM-366, the power supplies (+5, -5, +15, -15) were all okay. As soon as I plugged in the power cable to the KLM-366, all voltages started to drop and one of the fuses would light up and blow within a few seconds. Pulling one pin out of the 366 power cable (pin 2, +5V) stopped it from blowing the fuse. Changing to a different KLM-366 did not make any difference. I tried another KLM-376 (regulators) and everything worked, so I started to test all the parts on the bad KLM-376 as best I could. Diodes, capacitors and transistors seemed to test okay so I changed the M5230, and now it is happy. Since the capacitors tested okay and I didn't see anything else in the schematic that could short directly from +5 to ground, it seemed like the most likely culprit.
Don Backshall