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Post subject: Acceptable A/C leakge across a bypass capacitor in a AB763
Posted: Wed May 18, 2011 6:51 am
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Roadie
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Is there an acceptable leakage? Also how do I measure that properly with a DVM?
Unit selected to measure A/C.....probe across the cap with amp running at idle with no inuput signal?? Thanks


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Post subject: Re: Acceptable A/C leakge across a bypass capacitor in a AB
Posted: Wed May 18, 2011 8:22 pm
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A/C leakage? Usually A/C stands for air conditioning. :lol: If you mean AC (alternating current), a cap is supposed to "pass" AC. But, DC leakage should be very little (none ideally). I don't know if you can accurately measure the leakage with a DVM other than to check from ground to each side of the cap for DC voltage difference, with the amp at idle. Depending on the cap it should be a very low percentage of the applied voltage. The best way to check for leakage would be to use a capacitor checker with the leak test function, with the cap out of the circuit. :idea:

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Post subject: Re: Acceptable A/C leakge across a bypass capacitor in a AB
Posted: Wed May 18, 2011 8:33 pm
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Roadie
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thank you and I apologize for my lack of knowledge. I actually did want to ask about DC voltage but for some reason I had AC voltage on my brain.
Pretty funny with the HVAC comment as well... :lol:


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Post subject: Re: Acceptable A/C leakge across a bypass capacitor in a AB
Posted: Wed May 18, 2011 10:07 pm
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That's OK, I thought that maybe you had a hybrid amp with a built in A/C that was leaking freon. :lol: I do A/C also!

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Post subject: Re: Acceptable A/C leakge across a bypass capacitor in a AB
Posted: Thu May 19, 2011 3:41 am
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To check leakage on capacitors, ( DC volt) the caps use on the amp signal chain. Not the one on your AC power cord ( sometimes call dead capacitor ).

On DC ( signal ) capacitor ;

1- mesure the side with highest voltage , amp power on ( danger)

2- desolder the side wich have the lowest voltage, amps power off, filter caps discharged.

3- mesure the voltage on the disconnect side of this cap, amp power on ( danger). You should'nt mesure more than 0.01 volts this side. Mesure the other side if you have higher voltage make sure you disconnect the right side.


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Post subject: Re: Acceptable A/C leakge across a bypass capacitor in a AB
Posted: Thu May 19, 2011 6:16 am
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Aspiring Musician
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All caps can pass AC volts but not DC volts. The easiest way is to unsolder the grounded side and run you DVM from the unsolder-ed side to the chassis ground if you get .2 DC volts or higher the cap is bad a replace.


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Post subject: Re: Acceptable A/C leakge across a bypass capacitor in a AB
Posted: Thu May 19, 2011 6:21 am
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Roadie
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stratele and joncarr1979.....thank you for the instructions. I will get it done!!!


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