dating electrolytic capacitors -how?

[jaunty]

so ...

i'm constantly working on my own gear in my recording studio - a lot of it is second hand and much of it has rework done on it - one problem always seems to come up - determining the general vintage of electrolytic caps - although yes - there can be clues like soldering done - often it is difficult if not impossible for me to tell the age of a replacement (or original capacitor) - I couldnt' really find much about this on google ... are there any magic recipes for determining the age of a cap like date codes etc (not that i can tell - and it seems to vary by manufacturer from what i can tell as well)

[Shock]

Date codes, size, series, age of equipment.
Look at datasheets or google how to read the date codes.

If the caps are a crap brand or series or known/tested defective the date doesn't mean much. Not all electrolytic caps have to be replaced just normally crap brands and ones under heat or switching/filtering stress. If it was in service with big hours and there are problems after a few years then testing would be a good idea.

[Electro Detective]

If you do a lot of cap work it may be time to consider getting an ESR tester to do in circuit tests (with unit off!)

and comparisons amongst groups of same value caps

The really suss caps you will still have to unsolder one leg and test or just replace the old school way

Sometimes caps may have been replaced under warranty by manufacturer with different brands,
or someone threw in some 'close enough' values for an expedient repair,
you just don't know    
 

[Addicted2AnalogTek]

are there any magic recipes for determining the age of a cap like date codes

date codes are relatively simple and will usually be four digits printed on the cap. some of the brands have other digits included before or after the date code. Most that I've seen like this have had the four digit date code following some other digits that I don't know how to decode (and haven't bothered trying).

Date codes though....

AABB

AA is the last two digits of the year
BB is the week out of the year it was manufactured

Ex.  7742 is the 42nd week of 1977

[David Hess]

If you cannot read the date codes on the capacitors and they have not been changed, then instead read the date codes on the other parts to get an idea of the production date.

[Cerebus]

dating electrolytic capacitors -how?

Well, I'd avoid doing it until you've had the talk from your electronics tutor. The one that begins "When an NPN transistor and a PNP transistor love each other very much...".



Sorry, couldn't resist. 

[Shock]

dating electrolytic capacitors -how?

Well, I'd avoid doing it until you've had the talk from your electronics tutor. The one that begins "When an NPN transistor and a PNP transistor love each other very much...".

I find that last comment very biased. They clearly weren't darlings.

[KNSSoftware]

dating electrolytic capacitors -how?

Well, I'd avoid doing it until you've had the talk from your electronics tutor. The one that begins "When an NPN transistor and a PNP transistor love each other very much...".

I find that last comment very biased. They clearly weren't darlings.

Now now, I thought we were all better than this here, than to judge a couple of trannies; Grindr, Tindr, Wattever trips your switch

[IanMacdonald]

Well, I'd avoid doing it until you've had the talk from your electronics tutor. The one that begins "When an NPN transistor and a PNP transistor love each other very much...".
Sorry, couldn't resist. 

Well, if they're both trannies they should be in for a gay time.