capacitor testing

aragorn723 · 1454

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Offline aragorn723

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on: July 28, 2017, 03:27:04 PM
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



Offline braubeat

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Reply #1 on: July 29, 2017, 05:12:54 AM
that's probably two capacitors in one package. test each one separately.

Michael



Offline aragorn723

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Reply #2 on: July 29, 2017, 03:29:38 PM
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  :P  Does that make sense?

Dave
« Last Edit: July 29, 2017, 03:31:28 PM by aragorn723 »



Offline 2wo

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Reply #3 on: July 29, 2017, 04:26:40 PM
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   

John S.


Offline aragorn723

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Reply #4 on: July 29, 2017, 04:35:54 PM
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



Offline Paul Birkeland

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Reply #5 on: July 30, 2017, 06:53:06 AM
That style of cap hasn't been around for very long, what leads you to believe that it's a problem?

Paul "PB" Birkeland

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Offline aragorn723

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Reply #6 on: July 30, 2017, 02:45:26 PM
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



Offline aragorn723

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Reply #7 on: August 09, 2017, 04:23:17 PM
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