Re: Dell GX620
That's a good sign but not enough to call it good.
The reason is the test signal from those is at 100kHz.
A standard Multi-meter uses a DC test signal.
You need to know what the cap is doing at DC.
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You DON'T need a fancy or high accuracy meter for this.
You aren't looking for a specific number, just 'high' or 'low' as like a go/no go check.
A cheap $5 [or $2 at some places] would do fine.
An old style analog meter [one with a needle] is much easier to use for this check because the needle swings to one end or the other quickly and you don't have to wait for 5+ second on each cap for the digital numbers to stop changing. - No so much of a bother when you are only checking 3 or 4 caps but it gets OLD quick if you have more caps to do.
Note: When you check can't know the caps initial charge vs discharge condition. Even if you short the cap first there is some residual charge. Polarity of the leads doesn't matter but you do have to wait for charge-discharge of the cap to steady out if you have leads reversed from the caps actual condition. The DC test signal in the meter will charge the cap in the direction of the lead's polarity.
- If the cap [assuming a good one] is partially charged in the direction of the leads polarity then it will go high and stop [or slow WAY down]. That point is where the meter should read way high.
- If the cap [assuming a good one] needs to discharge then charge to match the leads then with an analog meter you will see it go low, might pause, then it will go way high and stop [or slow WAY down]. Once all the excitement is over you have your meter reading.
- With a digital meter all you will see is numbers flashing and you won't know where it is in the cycle [or if it's done] so you end up waiting longer for a steady reading. With an analog meter when you see the reading way high and the needle is slowing to a stop you can call it good without waiting for it to stop completely.
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Originally posted by speg_head
The reason is the test signal from those is at 100kHz.
A standard Multi-meter uses a DC test signal.
You need to know what the cap is doing at DC.
-
You DON'T need a fancy or high accuracy meter for this.
You aren't looking for a specific number, just 'high' or 'low' as like a go/no go check.
A cheap $5 [or $2 at some places] would do fine.
An old style analog meter [one with a needle] is much easier to use for this check because the needle swings to one end or the other quickly and you don't have to wait for 5+ second on each cap for the digital numbers to stop changing. - No so much of a bother when you are only checking 3 or 4 caps but it gets OLD quick if you have more caps to do.
Note: When you check can't know the caps initial charge vs discharge condition. Even if you short the cap first there is some residual charge. Polarity of the leads doesn't matter but you do have to wait for charge-discharge of the cap to steady out if you have leads reversed from the caps actual condition. The DC test signal in the meter will charge the cap in the direction of the lead's polarity.
- If the cap [assuming a good one] is partially charged in the direction of the leads polarity then it will go high and stop [or slow WAY down]. That point is where the meter should read way high.
- If the cap [assuming a good one] needs to discharge then charge to match the leads then with an analog meter you will see it go low, might pause, then it will go way high and stop [or slow WAY down]. Once all the excitement is over you have your meter reading.
- With a digital meter all you will see is numbers flashing and you won't know where it is in the cycle [or if it's done] so you end up waiting longer for a steady reading. With an analog meter when you see the reading way high and the needle is slowing to a stop you can call it good without waiting for it to stop completely.
.
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