Re: Capacitor Value affirmation, 19C: ME needs EE Help! Message #6 Posted by Randy on 24 Sept 2012, 10:05 a.m., in response to message #5 by Frank Boehm (Germany)
The value in question is 3900 pf. Yes, it really is rated at 250 volts. The .001 uf (1000pf) is indeed rated at 1000v and was a common part back when the machines were built.
Unless the leads are physically damaged, there really is no need to replace them. They are high quality ceramic disc capacitors and they are pretty much impervious to corrosion.
The 3900pf cap is important as it establishes the frequency of operation of the switch mode power supply. The .001 uf is in the printer circuit and could be ignored until you get the calculator portion operational.
I would be careful when working on the board in question, it is very thin and is multi-layered (most likely three). A good desoldering station is a must. A hand held solder sucker or desoldering braid may cause more problems than you solve.
Edited: 24 Sept 2012, 10:08 a.m.
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