NotTaR of Television Sets : High voltage to focus short             
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High voltage to focus short

Symptoms would be (with the unit powered and high voltage present):

If the CRT is gassy or up to air, forget it - it might make a decent fish tank :-). In this case, there would be visible arcing INSIDE the CRT probably not confined to a single location.

However, if there is just a metal whisker between the F and HV, that might be able to be cleared by careful tapping or a charged capacitor. You may even be able to see it if you were to remove the yoke - the gap is pretty large, about 1-2 mm - the last gap between electrodes before the start of the internal (Dag) coating.

See the section: Rescuing a shorted CRT.

Note that other damage may have been done as

Other components including the flyback, HOT, and parts on the CRT neck board and beyond, may have been damaged as a result of the short. Zapping the CRT may be just the beginning of what is required to repair it all.