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#1
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SP-600 Rebuilding Experiences
Steve wrote: I'll second what Frank suggests about replacing ALL of the black beauty caps. I'm doing that now on the SP-600 I'm restoring. While none were a dead short, most showed some leakage, about 100K ohms. In many circuits, that won't cause a problem but in some its a big deal. About 1/3 had cracked cases. Steve Ditto on the Black Beauties, especially the ones with the little brass tube, they seem to leak like crazy. More on the average than wax capacitors many decades older. Also bad news are those pea-green molded caps with the color bands. Many Trans-Oceanics have around two dozen of those, all leaky. I havent seen any major problem with postage-stamp or dipped silver-micas, maybe it was just one manufacturer's kind that is getting flaky? There is the problem of the silver migrating on silver-micas with considerable DC voltage across them. |
#2
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SP-600 Rebuilding Experiences
Ancient_Hacker wrote:
Also bad news are those pea-green molded caps with the color bands. Many Trans-Oceanics have around two dozen of those, all leaky. I havent seen any major problem with postage-stamp or dipped There is one variety of capacitor that looks like the silver mica "postage stamp" type of capacitor with all of the dots, but isn't a mica at all. It is just a paper capacitor. They are usually dark brown in color, and fail at about the same rate as normal wax/paper capacitors. -Chuck |
#3
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SP-600 Rebuilding Experiences
Don't let the "mica" caps fool ya. I chased an AGC problem for two days
before I found a bad "mica" buried in an IF can. That was the straw that broke the camels back. I then replaced ALL micas along with every bumble bee, which, by the way, were all cracked. -- Regards, Gary...WZ1M "Chuck Harris" wrote in message ... Ancient_Hacker wrote: Also bad news are those pea-green molded caps with the color bands. Many Trans-Oceanics have around two dozen of those, all leaky. I havent seen any major problem with postage-stamp or dipped There is one variety of capacitor that looks like the silver mica "postage stamp" type of capacitor with all of the dots, but isn't a mica at all. It is just a paper capacitor. They are usually dark brown in color, and fail at about the same rate as normal wax/paper capacitors. -Chuck |
#4
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SP-600 Rebuilding Experiences
gkb wrote: Don't let the "mica" caps fool ya. Well, your milage may vary. I've clipped out at least a thousand old wax caps, two hundred plus plastic tubulars, and lesse, three discrete mica caps, and around eight of those wafer mica caps built into IF can bases. Mica's can go bad, they just don't seem to do so very often IMHE. |
#5
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SP-600 Rebuilding Experiences
"Ancient_Hacker" wrote in message ups.com... gkb wrote: Don't let the "mica" caps fool ya. Well, your milage may vary. I've clipped out at least a thousand old wax caps, two hundred plus plastic tubulars, and lesse, three discrete mica caps, and around eight of those wafer mica caps built into IF can bases. Mica's can go bad, they just don't seem to do so very often IMHE. Well, I've replaced 4 in my JX-17. That does seem unusual but I think they suffer from the same problem other molded type do, namely shrinkage of the case. These do not get leaky like the BB's but become very unstable. -- --- Richard Knoppow Los Angeles, CA, USA |
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