CRT Heater problems

[Swann1]

Hello all,

This is my first posting on here, and my first television repair! so here goes.

I'm currently trying to locate a problem with a Sanyo 28inch TV controlled by a Phillips UOC. The set appears to be dead, however, I’ve tested the start up, the HOT and the LOPT - well all the voltages appear to be about correct - I think the problem is the CRT heater as when the system is on I get no orange glow from the base of the tube -even with all the lights of in a dark room I get no light at all- but the required voltages seem to be present (~7V).

I have also put an ohmmeter across the heater to try and measure the DC resistance, which, from what I’ve read, should be a filament, but I get an infinite resistance???

My questions are as follows,
1) Would the infinite resistance imply that the heater has gone open circuit, or is this usual for this type of heater?
2) Would this completely disable the set, or can the electrons travel on indirect heating alone? - Note: I’m getting nothing from the front of the screen at all!

Any help on this matter would be greatly appreciated, as I mentioned, this is my first TV repair - well, that's not including the one I blew up in the process of repairing a few years ago.

Kindest regards

Steven

[vtech]

Sounds like you've pretty much nailed it. Regardless of any other problem, the filament must always be a closed circuit & although rare, sure sounds like an open filament---(just make sure settngs on the meter are not responsible if using non-auto range meter).

You'd have to have filament for CRT operation.