Re: [TCML] CRT wire - harvesting safely

[Sfxneon@xxxxxxx]

Consider any intact CRT as a potential bomb which must be disarmed before  
it is safe to work on. CRTs are under a hard vacuum, so for every square 
foot of  surface area, atmospheric pressure is trying to crush it with over a 
ton of  pressure. (atmospheric pressure ~ 14.7 PSI x 144 sq. in. = 2116.8 
lbs.) Even a  scratch can weaken the glass to the point of failure. If you 
still plan on  disarming a CRT, wear eye and face protection and gloves.
 
The safest way to equalize the pressure is to snip off the vacuum tip,  
which is located in the center of the back of the neck. It's usually exposed on 
 smaller "baseless" tubes and under the center "key" of the Bakelite bases. 
Use  wire cutters to snip the glass tip (called the tubulation) just enough 
to allow  air to slowly enter the tube. If it has a Bakelite base, you'll 
need to  carefully crush the center key to expose the tip, and then snip it 
off. It's  usually too difficult and risky to try to remove the whole base.
 
Something else to consider it that CRTs are in effect, a Leyden  jar 
capacitor, and can store a potentially hazardous charge for a very long  time! Be 
sure to first discharge the CRT by connecting a ground wire to the  chassis 
(or the conductive outer coating on the CRT) and then touching it to the  
second anode button on the side of the CRT. Keep it there a while because a  
residual charge will build back up if only touched briefly. 
 
Tony Greer
____________

In a message dated 2/7/2010 2:59:24 P.M. Central Standard Time,  
brianh4242@xxxxxxxxxxx writes:


I managed to get the CRT out of a  little old portable TV, with a 4 by 5 
inch screen, and it has lots of lovely  copper wire that I want to get out and 
use for a secondary coil.  I know  these tubes are under a vaccum of sorts 
and I will have to melt off a bit of  glue and bend off some posts with 
pliers, so should I pop the tail end of the  tube before I start trying to 
extract the wire?  If so what is the safest  way to pop a tube or otherwise get 
at that  wire?


---------------------------------- 
Brian Hall 
 
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