Philco 50t1400 pic question - Videokarma.org TV - Video

radionut · #1 10-10-2015, 07:22 PM

Hi all, got an interesting issue with my re-capped 50t1400.It plays very nice with a strong pic when first turned on.After 20-30 minutes the pic starts to dim and then I lose the pic and can't get it back with any type of adjustment.The pic is there but not visible and looks scrambled.The sockets were cleaned with de-oxit etc.Now....the biggie here is where do I start trying to run this down? Bad tube,bad "new" cap,resistor? I don't have a scope so trying to pinpoint may be dicey. If any of you experienced tech's can point me in a direction?

If the set is cold it plays perfectly..........I know I know this can be a pain to find.With the pic getting dim that may be a clue??

zeno · #2 10-11-2015, 09:16 AM

Sounds like the hoz osc is drifting maybe. That will
scramble the pix and the HV will drop darkening it.
Start with hoz osc tube, its quick & easy. BTW
dont trust a checker. Use a known good new tube.
If you can get a screen shot that may help us too.

73 Zeno

old_coot88 · #3 10-11-2015, 09:58 AM

A vid would be even better.

radionut · #4 10-20-2015, 03:55 PM

I think I have a loose connection in the yoke.I gently tapped it when the pic went crazy and it came back? .The pic is getting fuzzier the longer it's played. When it's first turned on the pic is very sharp,after 20-30 it's loses it crispness.Does that sound like a tube?

Electronic M · #5 10-20-2015, 04:58 PM

Have you replaced the selenium rectifiers (if it don't use tube B+ rectifiers)?

stromberg6 · #6 10-20-2015, 08:57 PM

Connect a voltmeter after the dropping resistor that supplies the tuner. If the voltage starts to drop, and the resistor becomes hot, you may have leaky feed through caps in the tuner chassis. I have that problem in both the 50T1440, and the smaller 10 inch Bakelite set that uses the same chassis. I have yet to get back to them, so I'm sorry I don't have a workable solution yet. Kevin