Bob the Tech Audio recently serviced this McIntosh C37 which was blowing fuses. I don’t have any good pictures, but a shorted capacitor tied to the power transformer secondary, at the input end of the rectifier for the +/-15V supply, had shorted and pretty much vaporized.
Further inspection found some prior rework that is worthy of our Hall of Shame. Somebody had jumpered the front panel lamp supply fuse in the backup power supply with a resistor. Jumpering a fuse is never a good idea, so we removed the resistor and installed the proper fuse.
Finally, we found that there was an intermittent issue where the unit would not power up properly. A cold solder joint on the neutral leg of the bus feeding the switched outlets at the rear of the unit was to blame. Flexing the chassis just right, the unit powered. Flexed differently it wouldn’t. We touched up that joint and the unit powers properly.
With the fuses and supply capacitor replaced, and the power bus reliably connected, we had the C37 running and sounding great in no time. One last task was to replace a burnt out front panel lamp.
If your McIntosh C37 is blowing fuses, or any other issues, contact Bob the Tech Audio for service.
