Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 07-30-2017, 10:21 PM
CPQ5360 CPQ5360 is offline
Florence
 
Join Date: Jan 2013
Posts: 39
Can CRTs hold a charge after they've been vented?

I feel like this is a dumb question, but I can't for the life of me find the answer by googling. I've got a bad 5" tube that I'd like to vent and keep as an ornament.
Reply With Quote
  #2  
Old 07-30-2017, 11:25 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
The charge is held between the inner dag and outer dag acting as capacitor plates and the glass acting as the dielectric. Venting makes no difference, except that the charge might leak off faster due to humidity in the air.

Just discharge the tube properly before you vent it, and there won't be any charge to worry about.

REMEMBER that discharging once is not enough, because the glass dielectric can undergo electrical relaxation and restore part of the charge. To be safe, discharge once, wait 30 minutes or so and discharge again. On the other hand, relaxation is worse if the initial voltage is higher, so a 5 inch tube, which will use lower voltage, and have less total charge, is not going to have anywhere near the secondary charge that a large color CRT would have.

Edit: If the tube has been sitting around unused for months, it probably has no charge anymore, which you can verify when you get no spark on the first discharge.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #3  
Old 07-31-2017, 09:13 AM
Jon A.'s Avatar
Jon A. Jon A. is offline
Don't mess with Esther.
 
Join Date: Jun 2013
Location: Canada
Posts: 4,267
I accidentally zapped myself twice with CRTs that had been on recently, one of them vented. It'll get your attention but it's no big deal. I'm sure I got an even bigger hit from accidentally touching the case of the horizontal output transistor in my daily watcher while it was running. Again, no big deal. You're likely to get worse from touching a doorknob during cool, dry weather.
Reply With Quote
  #4  
Old 08-01-2017, 12:21 AM
Boobtubeman's Avatar
Boobtubeman Boobtubeman is offline
<---WANTED: Motorola 17P6
 
Join Date: Jun 2007
Location: Woodland Ca.
Posts: 931
I got a bite from a necked color tv once while pulling the remains of the gun out of the crt... The struggle is real..

SR
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:55 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.