Hallicrafters 505

[Bill Cahill]

Hello. I was begging for help on my customer's hallicrafters 505 tv in a thread at another forum. ARF. I have gotten alot of valuable inrormation from you guys concerning this set.

In my case, the baking did little good. My resistance on hv winding portion only checks 300 ohms against Sam's claim of over 400 ohmns.

I tried a couple experiments that John Folsom reccommended. I removed the chokes supplying voltage to oscilator tube from circuit they were in, connecting the choke that goes to the cathode to chassis ground, and putting other choke in sereies with approx. a 5-10 K 5 watt wire wound resistor to 400 volt B+. I even tried it on lover supplies. In my case, with my hv meter in place, I start off with 6500 volts, and as set warms up, ti quickly sags to under 2000 volts.

With chokes wired as originally wired, I start with 4500 volts, and after a few min, starts sagging down to under 1.9 kv with a nearly un watchable picture.
And, that being in a dark room.

I feel my coil is actually shorted. John doesn't agree, but, he sent me another he removed from a non working T-54. He replaced caps in that cage, and wired it to his own power supply. He claims it stayed at a steady 5000 volts for over half an hour. I'm awaiting that coil now, and will post my results.

I do reccommend his idea for sets with a weak pix. tube, If you make sure the hv doesn't go past, say 5000-5500 volts, you can get a brighter pix. Don't do this with a known good tube, though. You will only add retrace lines.

Well, that's what I know for now.

Bill Cahill