Thread: SMPS design ...
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Arfa Daily Arfa Daily is offline
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Default SMPS design ...



"Ian Field" wrote in message
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"Arfa Daily" wrote in message
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Are the 330pF multilayer ceramic that could have metalisation creep /
cracks/ unreliable /leaky from humidity. I would replace them with a
different brand/construction



It would probably be worth doing some further checks on those caps to
make sure that they are not any part of the problem


The low capacitance, high voltage disc-ceramics sometimes used for flyback
tuning in TV LOPT stage have been known to fail, ut its usually visible.

Sometimes the ceramic disc cracks and is usually visible because the resin
dip also cracks with it, sometimes they track around the edge of the
ceramic disc and burn a little "volcano" through the coating.


Yes, that's the type of cap that it is, and those modes of failure are my
experience of them also. These show no signs of anything like that, and
check ok for leakage - although not actually tested for this at high
voltage - and capacitance.

Arfa