Quote:
Originally Posted by Phil Nelson
I used to figure they should be good, too, but no longer. If you skim my CTC-7 article, you'll see a series of screen shots where things come together step by step as those caps are changed out. At first, the picture was a big fat mess with weak color. By the time I finished recapping, it looked pretty darned good, without doing any of the usual setup. I'm not curious enough to test old caps, so I can't say what defects they had -- maybe a little of everything. That TV sure works better without those maroon drops, anyhow.
Same deal with mica caps. I used to assume they were bulletproof, but now I find more and more bad ones. Maybe they're all getting older, just like me 
Phil Nelson |
I too have had problems with mica caps - mostly Sangamo molded ones - they are "pinker" than most.
The brown Elmenco "drops" are all mylar-paper caps, vacuum impregnated just like the old Sprague Orange drops. I've used them in sets for years, depleting my many assortment kits (Arco/Elmenco sold the "brown drops" in service kits years ago) and most of my sub-.01uF 600V stock. Never a problem with any of them. I've got tons, thanks to friends that shut down TV shops over the years. They sell the test equipment, but give away the parts.
I've had to quit using orange drops - the manufacturer (SBE) has shifted production to China. I found several new .0047uF Orange Drops that were leaky - several hundred microamps leakage at full voltage, giving me some freaky grid voltages in a Motorola radio I was working on for a guy at church. I think the shift to Rohs/lead-free or poor Chinese quality may be to blame. I've since shifted to Nichicon (XK series) and Illinois Capacitor (MSR/MPR) radials and axials. Much easier to obtain in small values, and cheap too.
There was an earlier thread talking about the Elmencos/maroon drops and problems, but nobody ever gave specifics. My Sencore LC102 and Sprague Tel-Ohmike both check caps at full voltage, so I've always relied on them for testing most caps. For quickie tests, I used to connect a 90V battery up to my VoltOhmyst with the cap in series to check for charge/discharge. Any residual voltage indicated leakage. I don't anymore - the dang battery went dead - ever price a new 214 battery these days?
I'm gonna re-read your CTC7 saga!
Cheers,