Hi Jeff, On the Digikey website, you can search for high frequency capacitors : it's in the "features" column when you go to the capacitors catalog. High Frequency capacitors can handle frequencies of over 1000 Khz, so they are typically found in sweep/video circuits of tube monitors/tv's. Most high frequency caps are also high stability one's, including the one I suggested, so they can handle higher currents and remain very stable ( 5% tolerance ) even on their maximum operating temperature.
The C1 replacement capacitor for the analog board really needs to be a high frequency one as it's in series with the variable inductor to serve the horizontal sweep. Schematics of the analog board can be found here: http://home.earthlink.net/~gamba2/images/plus_analog.PDF The suggestion of using 4 ceramic 1uf 100v capacitors will also work: it has the advantage the total capacitance ( and the heat ) is spread over 4 capacitors. Both solutions work well to replace the original capacitor. My personal choice is to use the radial polypropylene capacitor to keep the analog board as original as possible, even though it's regrettably not a round radial capacitor. I'm using these for many years without problems. Take Care, Nico -----Oorspronkelijk bericht----- Van: [email protected] [mailto:[email protected]] Namens Jeff Walther Verzonden: donderdag 7 juli 2011 18:01 Aan: Vintage Macs On Jul 6, 3:01 pm, "Nico Vanden Eynde" <[email protected]> wrote: . > You really need both Bi-polar and Highfrequency since the capacitor is in > the video circuitry to the tube. > > I'm using this one to replace the original capacitor: Digikey part > PF2395-ND, a Panasonic 3.9UF 250V Metal Polypro cap. How do you specify "high frequency" in terms that capacitor manufacturers use? For example, I don't think it's one of the filter boxes on Digikey's selection tool for capacitors. Tom Lee suggests using four 1uF 50V (or higher V) ceramic capacitors in parallel in place of C1. It makes a lot of sense. Jeff Walther -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/
