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I am in the process of replacing the capasitors on an old board. All was going fine as most capasitors have a negative and a positive leg. Then I pulled one that doesn't. I have replacment caps but they are +/- does it matter which leg goes where if the cap that came out had no indications of + or - ?
Is the capacitor you removed a cylindrical electrolytic capacitor? i think you should really replace like for like.
The polarity (the +ve and -ve order) of a capacitor is very important, get it the wrong way round and you'll blow it up.
With the polarity you can see by the artwrk on thee board.
On most electrolytics there is a dark band on the top of them. Look for the artwork and that may well also be shaded also.
Positive and negative with respect to what? ;) Anode and cathode :PQuote:
Originally Posted by DDY
Thats only if its an electrolytic and if you reverse bias it with a loooot of DC, more than a PSU is likely to give you.
Most electrolytics come in a dark blue container. Theres a light blue stripe going from top to bottom beside one of the pins, thats the cathode. That goes by the shaded line on the board.Quote:
Originally Posted by Blitzen
Most electrolytic capacitors will fail significantly below their forward bias voltage rating when reverse biased. For instance, I've managed to blow up 35V capacitors with only a 12V lab supply. It's never fun when they blow...Quote:
Originally Posted by Steve B
lies :P its the greatest fun on earth!Quote:
Originally Posted by timothius
what actually happens when a capacitor blows?
its only electrolytics that blow. Electrolytics are like a piece of metal toast with a jelly spread. The toast is rolled up, like a swiss roll and put in the wee container. When you reverse bias it, they can blow up. Shards of metal (if its a big cap) go everywhere, and the jelly stuff turns to fluff and covers everything.
Exploding an electrolytic capacitor by Synergic -- Revver Online Video Sharing Network
You misses what i said i think. You dont need to work out pos or neg if the artwork on the PCB is correctly done as it will follow the shading on the cap. (Well, the millions i have seen going through our SMT lines have anyway).Quote:
Theres a light blue stripe going from top to bottom beside one of the pins, thats the cathode. That goes by the shaded line on the board
Ahh ok, i'm forgetting that solid state caps are now used instead of electrolytics.
Like this you mean?
http://www.pcstats.com/articleimages...W9DMax_cap.jpg
Gotcha :D
Yeah, we had it demonstrated last year when we were building power supplies at Uni, was a tiny capacitor but it still made a decent bang!Quote:
Originally Posted by Steve B