Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Thanks a lot for this thread. I also had the exact same board & now works great. Had 3 blown & 4 fat caps. The diode was cooked and turned to powder when I tried to remove, I replaced it with a 1 watt'er.

Re: Troubleshooting electronics...

I agree, First look for blow fuses. Then look for or smell for anything that shows damage. This can be a bubble on a transistor or computer chip or faint discoloration to blown caps. Also look for tail tail signs of oil under caps. Many repairs are just the one bad component. If it is not obvious check for bad solder joints with plenty of light and a magnifying glass. I things are not obvious, then obtain and trouble shoot with the schematic. Good luck.

Re: voltage difference limit?

The Voltage is a Limit Rating. Nothing more nothing less. If the new cap is a higher rated voltage and there is room to install in the same spot it is ok to use, period. Its kind of like using a 1 gal pot for 1/2 gal water, any volume below 1 gal will work. You want to stay above the highest possible voltage the cap will ever see. Most high quality company's use 35% to 50% tolerance over rating to ensure stability. Low quality company's use only a 10% to 15% margin to cut cost. This is why Fisher & the like cost more but you get what you pay fo...