I¡¯ve had a big Sprague electrolytic in a lab supply, 60s vintage, fail in a Zener-like mode. Up to a couple volts it was fine, then its differential resistance dropped pretty much to zero per curve tracer.
I also was not quite expecting that.
Cheers, Kuba
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21 mars 2023 kl. 4:52 fm skrev Martin via groups.io <musaeum@...>:
?Hi all,
a W&G switching power supply in my SNA1 spectrum analyzer had a large 15mF filter cap with a total short. The screws showed some brown-black goo, otherwise no sign of failure like overheating. Another capacitor of the same type is perfectly in spec. Once the capacitor replaced the supply and the rest seems to work fine.
Up to now I thought these caps gradually loose capacity and go open. Here is the first time I've seen one shorted. The supply worked for 20 minutes or so before it failed. Before that it was unused for years, and when switched on it was stressed by a shorted through capacitor in the -12V supply. The 15mF capacitor belongs to the 5V supply, probably unrelated.
Any opinion on this?
cheers
Martin
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