On Tuesday, December 11, 2012 3:18:39 PM UTC-5, Bruce Hawkes wrote:
I have an old 365 that I still use. Lately the capacitor has been getting hot. Cap is rated 1800uf 400V

The flash works fine except for the heat.



On checking I found that there is 465V on the cap. Even hooking it to a "dead" battery that only had 8V during charging, the cap still had 430V on it. I believe the cap is getting hot from the overvoltage. I've checked the cap on a Sencore Z meter, an ESR meter and with an ohm meter and all indicate that it is ok. The Z meter showed a little dielctric absortion but not bad for a cap 30 yrs old and that size. Ohm meter tests in the 50meg I ran over all the diodes, resistors and semis that I could recognize. I found one semi in a TO-220 type package that reads 94 ohms between the outside leads. It reads .09 in both directions on a diode test. The tab-center lead reads around 5meg to the other 2 leads and counts up like a capacitor charging.. I have searched extensively on the net for info on this device and have found nothing. Anyone know what this is and if it's good or bad? My thoughts are that it is used to regulate the voltage applied to the cap and is not working. Any and all advice is apprecaited.


The handle of the flash unit where the cap is housed gets so hot you can't hang on to it. That's what prompted me to take it apart.

I have put the cap back on the Z meter and one an intensive leakage test on it. The meter has 396V across the cap (measured with an external DVM) and is only showing 440 microamps of current through the cap and it's cool after 15-20 minutes of this voltage applied. No signs of heating at all. It appears the cap survived being over heated/charged drastically. I have no idea how they monitor/regulate the voltage. The circuitry is pretty simple with no processors or logic involved that I have found. I'm beginning to doubt if the 3JM device is involved in that control, but I still don't know.