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ArcticMyst Security by Avery

Shocked by dead HeNe

Joined
Dec 31, 2012
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I bought an older (sealed) HeNe from eBay hoping she might lase. I hooked her up to a PSU and I see no output. Not even plasma glow. :yabbem: Poopy.

The funny thing is, when I unplug her, I’ve been shocked by the exposed HV connections at the Alden connector - several times in the last few days.

I know very well the capacitors within a recently charged PSU can zap you. That’s why you see them protected by the female Alden connector in most cases. But from the laser head, I can’t recall ever being zapped – and I’ve handled a good number.

Under what conditions will a HeNe tube hold a charge like that?
 





ARG

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Feb 27, 2011
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I've been zapped by HeNe tube before, I have one that struggles to ignite. When I give up trying to make it work and unplug it the results are shocking :shhh:
 
Joined
Mar 10, 2013
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Indeed the tube itself is capacitive and needs discharging unless it's made sealed, then it usually has a bleed down resistor. What tube is it?
 
Joined
Jul 27, 2007
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Yup, even working HeNes exhibit this behavior. The tube itself is a capacitor (two electrodes separated by an insulator) The zap is usually bigger for tubes that don't ignite since you get the full starting voltage of the HeNe psu instead of the operating voltage (2-3x lower)
 

SKeeZ

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Sep 2, 2013
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pretty interesting. hoping i don't get shocked. its usually quite shocking- ha. pun intended
 




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