Black = negative Cap

[Calebay]

Hello

i have 4 older caps 22000uf 80V from a sony ES power amp

but i have no idear what is + and -

Black= negative or is it the other way araund? see pic if that help


Tnx

 

[peranders]

Do you have any text printed on the can?

 

[Calebay]

this is all it says

 

[peranders]

Take a DVM and measure the resistance between the terminals and case. Normal negative is more or less connected to case.

 

[Calebay]

im not able to measure anything infinity resistance

anything else i can try before i connect my 450VA trafos?

 

[jan.didden]

Try it with a 12V trafo through a resistor of say 100 ohms first to see if the caps are connected correctly. If not, you will see a very large current resulting in low voltage at the caps. Can you measure voltage? And oh, btw, you didn't mention the rectifiers, but you have those too?

Jan Didden.

 

[Calebay]

okay ill try that first yes i have a multi meter i did try to measure the but it seems like the non of the terminals have any connection to the case at all..


don't worry i have rectifiers in there as well i have build an amp before

 

[Calebay]

okay i did this test using a 9v batt instead i connected my multimeter in serie whit the batt. to measure the current

when i connect it to the cap the same this happens no matter if its + or - it draw a large amount of current the first few seconds, then drop to zero. seems normal..

i also try to measure the voltage over the cap after its been charged. its drop for 9 volt slowly. the same speed + and -

 

[Peter Daniel]

Maybe this helps:

 

[Netlist]

Somewhere on the board there's a clever post how to measure polarity with a scope, looking at dropping waveforms. I can't however remember who posted it, when and where.

/Hugo

 

[jan.didden]

okay i did this test using a 9v batt instead i connected my multimeter in serie whit the batt. to measure the current

when i connect it to the cap the same this happens no matter if its + or - it draw a large amount of current the first few seconds, then drop to zero. seems normal..

i also try to measure the voltage over the cap after its been charged. its drop for 9 volt slowly. the same speed + and -

Yeah well I think 9V is a little too low. Try, if necessary, with your big transformer but with a series resistor. I would also vote for the black terminal being neg pole, btw. It seems pretty standard.

Jan Didden

 

[Peter Daniel]

Somewhere on the board there's a clever post how to measure polarity with a scope, looking at dropping waveforms. I can't however remember who posted it, when and where.

/Hugo

http://www.diyaudio.com/forums/showthread.php?s=&threadid=35471&highlight=

 

[Netlist]

That's the one, Peter. Seems you don't need the search engine, you know the threads from memory.

/Hugo

 

[Peter Daniel]

Actualy I remebered that Moamps used the name Fred in this thread, and this is how I did my search.

 

[Netlist]

Leaves us with the question: Is the inner or outer foil + or - ?
Or should I re-read the thread?

/Hugo

 

[Calebay]

yep also got a cap thats says negative = black

i did the test agin this time using 2 9v batt in serie ´Better

the black was negative

i also tried using the scope test. but no luck whit that one don't know what i did wrong..

tnx for the help