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Discharging a Cap- best method?

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  • Components
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February 6, 2012 1:46:40 PM

Hello,

I want to be sure the caps I replace on boards are safely discharged before I handle. What are the best ways to do that?

More about : discharging cap method

February 6, 2012 2:22:32 PM

Hi :) 

If you are replacing the capacitors on a motherboard, I hope you have a LOW temperature soldering so you dont take out the nearby tracks....I SERIOUSLY doubt it will ever start again though....

To answer your question...use a screwdriver WITH INSULTED HANDLES to discharge them.... wear SAFETY GLASSES and SAFETY gloves...JUST IN CASE...

All the best Brett :) 
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February 6, 2012 2:25:22 PM

Brett928S2 said:
Hi :) 

If you are replacing the capacitors on a motherboard, I hope you have a LOW temperature soldering so you dont take out the nearby tracks....I SERIOUSLY doubt it will ever start again though....

To answer your question...use a screwdriver WITH INSULTED HANDLES to discharge them.... wear SAFETY GLASSES and SAFETY gloves...JUST IN CASE...

All the best Brett :) 


I saw someone doing that on youtube and the cfap was off the board. Wasn't sure how to do if the cap is stuck right to a board and if discharging with a screwdriver could harm the capacitor in any way.
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February 6, 2012 2:37:28 PM

You can damage the capacitor by shorting it, because they are rated to release so much current at a time - but NOT a short. I'm assuming you are replacing aluminum electrolytic or tantalum caps, though. These need to be soldered in correctly (they are polarized). Make sure you note the original caps' orientations, otherwise you may damage much more of the board.

To ensure the caps are discharged, simply remove the board from power for a long time, like a day or so. The internal resistance will slowly discharge the caps, as well as any resistance across the caps.

Like Brett said, make use of insulation.

If you can, reduce risk of ESD by grounding your skin with a ESD wrist strap.
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February 6, 2012 2:39:26 PM

Lick them.
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February 6, 2012 5:26:22 PM

willard said:
Lick them.


Hi :) 

Lol...good way to put a hole in your tongue... :( 

All the best Brett :) 
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February 6, 2012 5:58:04 PM

and if you don't know the answer to this yourself then don't do it. Get a Mohm resistor or some pencil lead and put that across the legs, it'll be slow enough not to damage it.
But if its the one you are removing why do you care about damage.
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February 6, 2012 6:06:20 PM

13thmonkey said:
and if you don't know the answer to this yourself then don't do it. Get a Mohm resistor or some pencil lead and put that across the legs, it'll be slow enough not to damage it.
But if its the one you are removing why do you care about damage.



Maybe I'm upgrading the caps on an amp and would like to recycle the ones I'm removing.

Common people, work with me... :pt1cable: 
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February 6, 2012 6:19:07 PM

well, as stated above use a big fat resistor. Or pull the power from the wall whilst the amp is playing, you'll hear it pull the power down.

But learn some electronics, so that you can figure this out for yourself, and more importantly, far more importantly, spot the other problems that you don't know to ask us about.

I've built the aforementioned amp, and honking great big power supply, by the way.
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February 6, 2012 6:32:52 PM

willard said:
Lick them.


Can I vote this as best answer :) 
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February 6, 2012 7:26:54 PM

In the days of CRTs, I had a special cable keyed to ground when plugged into an outlet. I'd fasten it to a screwdriver with a clip, then gently prod the capacitor to discharge it. :)  You'll know pretty fast if you do it wrong. It's a great learning experience and will quickly teach you to respect electricity.
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