capacitor testing

[aragorn723]

Anyone know how to test a capacitor with 4 leads?  It is the power supply capacitor in a integrated amplifier (soldered to a board).  Thanks,

Dave

 

[braubeat]

that's probably two capacitors in one package. test each one separately.

Michael

 

[aragorn723]

Funny thing about the cap though, is that is looks like 2 of the leads aren't connected.  Only 2 of the leads have traces going to them..  The solder joints for the caps are the diamond shaped patterns in the attached picture.  Oddly enough the other 2 are soldered also    Does that make sense?

Dave

 

[2wo]

Yes it does, the extra leads are just attachment points for a stronger mounting. If look closely at the label they are probably marked in some way...John   

 

[aragorn723]

Gotcha.  Should I go ahead and de-solder one of these monster caps to test it, or would it be better to check some of the voltages first?  I suspect one of these 3300 uf caps blew (part of the power supply) but don't have anything to back that up yet, except a toasted resistor after the driver stage of the circuit.

Dave

 

[Paul Birkeland]

That style of cap hasn't been around for very long, what leads you to believe that it's a problem?

 

[aragorn723]

There's a smoked resistor after the driver stage, which suggests an overcurrent situation.  Also, there is no sound.  I could just swap out the resistor, but something upstream caused the issue, and right now that cap is the only thing I can think of.  Am I missing something?

Dave

 

[aragorn723]

Here's a quick update to the amp situation.  Turns out that resistor is ok.  According to the schematic, it is supposed to be 470 ohms, and measures at 469 ohms.  I thought for sure that would be toast??  Looks like it's time to check some voltages.

Dave