and how should I test them for "bad-ness"?
-Colin
I test them In a ckt to see what they do...yes this is tough when they're soldered in.
There are cap checkers I don't have one and good ones arent cheep sfars I know.
5-10 years probably before you have to worry about them drying out, depending on heat and humidity conditions.
They take heat up to a point of course, I don't think I've ever damages a cap from heat...well the side of the iron on the side of the cap once, but I replaced that one.
Tantalums last longer and are less temp sensative.
I think they last generally much longer than ten years, I have some I'm using that are more like 50 years old, if they're bad, I can't tell...I shouldn't type such things, like I need to go in there and fixxey [not YET !!?]
Tube amps tend to dry them out I would thing more than pedals, they warm up and down sometimes in a tube amp.
No well i haven't had much in the way of cap problems lately knock on wood...
It's really only the electrolytics you have to worry about in effects. Their stated shelf life (time sitting on the shelf unused) is 10 years generally. If you use them constantly they won't break down anywhere near as fast. They will last a very long time if the seals are good and the cap remains charged. If discharged and idle, that shelf life is ticking away. Interestingly, electrolytics will repair themselves (for the most part) when charged (it's actually called reforming).
Bad caps usually have a bulge somewhere or show signs of having leaked through the seal. They're really hard to test in-circuit unfortunatly. I got luckly once on an old TV and found a bad cap by lightly rocking each cap. The failed one acted like one of the two leads was not connected.
Except for the oldest effects, you shouldn't encounter many failures. They last a lot longer than the 10 years of shelf life.
Take care,
-Peter
Mmm... then I guess it must be the caps in this 1970's DMM that are going bad.
-Colin
I'd be suprised if caps went bad in a DMM, in fact it is hard to think that caps do much in a DMM at all. What are the DMM symptoms?
QuoteI'd be suprised if caps went bad in a DMM, in fact it is hard to think that caps do much in a DMM at all. What are the DMM symptoms?
Same here. Perhaps there might be one in the rectifier stage. There's probably not many electro's in there anyway, just replace them.
Mostly that it's being extraordinarily noisy.
-Colin
QuoteMostly that it's being extraordinarily noisy.
Must be the capacitor in the rectifier/PSU.
How long do caps last? A very long time.
Even though they say that they have a shelf-life of about 10 years, I've found it can be as high as 35-40 in normal room tempreature, but it depends on the quality of the device, and how well they are sealed in the manufacture process. The digital quality "Micro" caps (Available from Maplin) seem to be of really high quality - check them out!
humbuck.
Oh! sorry someone has already said that!
I think I hava a schematic for a capacitor tester somewhere - I'll see if I can dig it out!
H.
Whoops! it occurs to me today that DMM might not mean "digital multi meter". Oh well.... :oops:
Quote from: Paul Perry (Frostwave)Whoops! it occurs to me today that DMM might not mean "digital multi meter". Oh well.... :oops:
Deluxe Memory man... although I guess this is a "MM" :)
Thanks for the tip. There are maybe 5-10 electro's in there.
-Colin
Quote from: Paul Perry (Frostwave)Whoops! it occurs to me today that DMM might not mean "digital multi meter". Oh well.... :oops:
Deluxe Memory man... although I guess this is a "MM" :)
Thanks for the tip. There are maybe 5-10 electro's in there.
-Colin
Quote from: Paul Perry (Frostwave)Whoops! it occurs to me today that DMM might not mean "digital multi meter". Oh well.... :oops:
Deluxe Memory man... although I guess this is a "MM" :)
Thanks for the tip. There are maybe 5-10 electro's in there.
-Colin