Discharging start capacitor before removal


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Old 06-22-09, 07:02 PM
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Discharging start capacitor before removal

I'm replacing the start capacitor on my RV air conditioner with a hard start capacitor (Supco SPP6E). What is the best way to discharge the capacitor that is on the unit now? I was told to use a screwdriver to arc between the two poles. Will this work without causing any harm to the rest of my unit? Suggestions???
 
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Old 06-22-09, 09:29 PM
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Originally Posted by bob213
I'm replacing the start capacitor on my RV air conditioner with a hard start capacitor (Supco SPP6E). What is the best way to discharge the capacitor that is on the unit now? I was told to use a screwdriver to arc between the two poles. Will this work without causing any harm to the rest of my unit? Suggestions???
Not exactly the same but maybe you could do something like this.

Many years ago we used home-made probes with a resistor to discharge picture tubes. Pretty simple, just a larger gauge, sharpened probe wire soldered to one lead of the resistor, and a wire with an alligator clip soldered to the other lead. Disconnect power, connect alligator clip to ground, insert probe under anode cap, hear ZAP, remove probe, remove anode cap, probe hole again, all done. Seems to me we would leave the probe in place just to ensure there was no residual charge left.

This thread suggests using a 10K-ohm resistor, although I have used a screwdriver and an alligator clip jumper many times:
How to discharge high voltage in tv tube
 
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Old 06-23-09, 12:20 AM
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I used the screwdriver to short out the capaitors { only at the capaitor termail point anywhere else forget it it will not work the reason why due the starting switch can isoliated it that why I mention that in first place }

That I been done doing that for long time.

Merci,Marc
 
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Old 06-23-09, 05:17 AM
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The proper way to discharge a cap is to use a resistor as Arg suggested. It allows the cap to discharge slowly.

Wear safety glasses if you use a screwdriver. Capacitors can release all kinds of nasty chemicals when they explode. Remember, caps are just like batteries.
 
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Old 06-23-09, 08:35 AM
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Originally Posted by ArgMeMatey
Many years ago we used home-made probes with a resistor to discharge picture tubes.
This is the safe, correct way.

I used the screwdriver to short out the capaitors
This is the way pretty much everybody does it.

Some caps have a bleed resistor built-in so it will automatically discharge itself after a few seconds of no power.
 
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Old 06-23-09, 09:48 AM
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For discharging an ac capacitor do you need the power to the unit on
 
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Old 06-23-09, 09:53 AM
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Originally Posted by zacktx
For discharging an ac capacitor do you need the power to the unit on
Definitely not -- that could kill you.
 
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Old 06-23-09, 10:28 AM
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Thanks everyone. I picked up a resistor this morning. For less than $2, I'd rather be safe. Really appreciate all the help here!!!
Bob
 
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Old 06-23-09, 11:07 PM
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Originally Posted by zacktx
For discharging an ac capacitor do you need the power to the unit on

That is not a wise advise in here and it is too dangerous to do that.

Merci,Marc
 
 

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