Author Topic: Capacitor replacement question  (Read 342 times)

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Offline gkmaia

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Capacitor replacement question
« on: February 23, 2019, 07:39:20 pm »
Is it ok to replace these orange capacitors by these polypropylene ones?

They are part of the CRT power supply high voltage block. CRT runs at 1500v.

Also, I suspect the high voltage ceramic may not work for this use, but I do not understand why. Can anyone clarify a bit?
« Last Edit: February 23, 2019, 07:55:13 pm by gkmaia »
 

Offline SeanB

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Re: Capacitor replacement question
« Reply #1 on: February 23, 2019, 09:00:11 pm »
Ceramic capacitors will have a wide tolerance, thus your actual capacitance will depend on how long since they have been soldered, the actual material they are made from. This will mean capacitance will vary with temperature and applied voltage, possibly quite a bit, and the film capacitor however will not vary much in capacitance both from new, with time and with applied voltage and temperature. As they are pretty much the same price wise go with the foil one.
 
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Offline gkmaia

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Re: Capacitor replacement question
« Reply #2 on: February 23, 2019, 09:08:06 pm »
As they are pretty much the same price wise go with the foil one.

By foil one you mean polypropylene?
 

Offline jackthomson41

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Re: Capacitor replacement question
« Reply #3 on: February 23, 2019, 10:45:39 pm »
As they are pretty much the same price wise go with the foil one.

By foil one you mean polypropylene?

By foil, he meant ceramic capacitors.
 

Online ebastler

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Re: Capacitor replacement question
« Reply #4 on: February 23, 2019, 10:58:18 pm »
By foil, he meant ceramic capacitors.

No, he obviously did not. SeanB argued that foil (film) capacitors are preferrable, since they have better tolerance and stability than ceramics. And hence he recommended to use foil caps, since their price is similar to ceramic caps.
 

Offline David Hess

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Re: Capacitor replacement question
« Reply #5 on: February 24, 2019, 09:18:18 am »
High voltage polypropylene film capacitors will work fine.  High voltage ceramic capacitors will also work fine.  The only plastic film capacitor which could be problematical is polystyrene because of its low maximum temperature and high operating temperatures around typical CRTs.

 
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