08-15-2010, 02:18 AM
If the power supply caps are hard to get to, as with many of these older sets (some even buried in tar in the power supply section), could be the shop that did your repairs didnt replace them? If they did replace them, perhaps those caps are visible now? If so, you can jumper-in ( in parallel) across the filter supply caps with ones with abit higher UF rating, observing polarity with schematic, to help rid excess 60 cycle hum. Its trial & error test using added capacitors across what already is in place in the power supply. Most older sets use lower uf ratings with higher voltage ratings, and it can be dangerous jumping in added caps. High voltages are present in the power supply, so be VERY careful and let your orig caps discharge for several minutes before jumpering in any added uf rated caps. Never exceed more than minimal uf's needed to rid the hum because doing so can raise B+ voltages abit also, usually not that critical tho. For example, if the schematic calls for a 10 uf @ 450 volts, and you still have hum, try jumpering in with a set test wires with insulated alligator-clips on each ends,add another 10uf @ 450 volt cap in parallel with the orig cap already in place, observing positive & neg polarities on the caps. Many times you can hear the hum disappear instantly once the added uf's are connected.