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#1
02-11-2022, 08:47 AM
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Philco 48-700 assistance
While working on my Philco 48-700, the .4uf 3500v HV filter capacitor shorted and started smoking. Can I use a film capacitor in its place? Any ideas where to purchase an equivalent would be appreciated.
Thanks in advance 
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#2
02-11-2022, 01:10 PM
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Yes film should work fine. You may need to do series pair of 2KV .82uF.
Mouser doesn't have anything close to .4uF at over 3KV... Digikey might.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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#3
02-11-2022, 07:20 PM
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Possibly something like this, all I could find that was in stock:
https://www.digikey.com/en/products/...RLLckgqMXEdDqA All I could find that was close, If the voltage rating is insufficient you may need to special order something.
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#4
02-11-2022, 09:17 PM
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Quote:
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#6
02-12-2022, 10:17 AM
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Quote:
"In modern power electronics, they are commonly found to reduce ringing. A snubber circuit limits or stops (snubs) switching voltage amplitude and its rate of rise, therefore reducing power dissipation." VS what Electronic M mentioned, using 2 series pair of 2KV .82uF. bandersentv has done this many times, and would know the most about it.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#7
02-12-2022, 03:06 PM
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Another possibility, cheap (but a minor nuicsance to construct).
Replace the chain of resistors from the 0.5 uF cap to ground with a chain of (mostly) 200 volt 1.3 to 2w Zener diodes, with one different voltage to get the drop across the focus pot right. Then you can use a bunch of 630 volt caps at say 0.1 or 0.27 uF across triples of Zeners. Because the voltage is regulated, you would only need a lower capacitance to filter out the Zener noise. I've used such Zener chains in a couple of TVs and they work fine. Of course you have to figure out how to construct them.
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