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NotTaR of Television Sets : Warning about disconnecting CRT neck boa..
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1994-2007, Samuel M. Goldwasser. All Rights Reserved. Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: 1. This notice is included in its entirety at the beginning. 2. There is no charge except to cover the costs of copying.
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Some manufacturers warn against powering a TV or monitor CRT without the
CRT neck board connected. Apparently, without something - anything -
to drain the charge resulting from the current flow due to residual gas ions
inside the CRT, the shortest path may be through the glass neck of the tube
to the yoke or from the pins outside the CRT to whatever is nearby. There
aren't many ions in a modern CRT but I suppose a few here, a few there, and
eventually they add up to enough to cause a major disaster at least on some
CRTs.
This is probably not a problem on small CRTs but for large ones with high
high voltages and high deflection angles where the glass of the neck is
very thin to allow for maximum deflection sensitivity, the potential does
exist for arcing through the glass to the yoke to occur, destroying the CRT.
There is really no way to know which models will self destruct but it
should be possible to avoid such a disaster by providing a temporary return
path to the DAG ground of the CRT (NOT SIGNAL GROUND!!) via the focus or G2
pins preferably through a high value high voltage rated resistor just in
case one of these is shorted.
This probably applies mostly to large direct-view TVs since they use high
deflection angle CRTs but it won't hurt to take appropriate precautions with
video and computer monitors as well.