On a energized power supply will a capacitor voltage read the same on both leads? I have a dead power supply and I m trying to locate the bad area.
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capacitor in circut, powered up
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Re: capacitor in circut, powered up
Why not open a thread for it in a relevant section - post pictures and we will suggest
some testsPlease upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740
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Re: capacitor in circut, powered up
Originally posted by 13919 View PostOn a energized power supply will a capacitor voltage read the same on both leads?
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Re: capacitor in circut, powered up
It theoretically could on the primary side of the supply, but most likely will not.
Voltage across an individual primary cap could be as low as 170VDC, or up to about 400VDC if the PSU has active power factor correction.Last edited by Uniballer; 01-25-2014, 05:46 PM.
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Re: capacitor in circut, powered up
The capacitors have a negative side and a positive side.
If you want to measure voltage on capacitor, you can put the probes either way, the multimeter will measure the voltage difference between the two terminals. So, if you put the probes the other way around you'll just see the voltage with a negative sign on the multimeter screen.
You can't test if a capacitor is good by checking voltage on each side, it's not working like a resistor in the circuit.
In electronics electrolytic capacitors are almost all the time connected between the + and - of a power supply to store energy. They're not "in series" like a resistor. If you put a capacitor in series, that capacitor will only let AC move through it and DC will be blocked.
See this for something that will make you understand easier : http://electronics.stackexchange.com...citor-block-dc
later edit as you added a few posts while writing this:
Would the voltage be the same in and out????12v in 12v out or would they differ. 12v in nothing out ,I would assume would be bad.
On the secondary side, most power supplies tie the negative side to ground... the power supply is earth referenced. So if you put one probe on earth or chassis and the other on the negative side of the capacitor you would measure 0 or close to 0, with the probe on + you would measure the output voltage.
On the primary side, where those large capacitors are, it's a bit tricky. Often, that section is "floating" or in other words, not referenced to ground. The two AC wires from the socket come in a bridge rectifier and get converted to DC and you get a virtual ground (the -) and the virtual plus (the +) ... there may be no connection between the chassis and that - on the primary side.Last edited by mariushm; 01-25-2014, 06:17 PM.
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