Recapping Philco 51-PT1207, Headache

[Eric H]

I replaced most of the caps in this Philco and when I fired it up the vertical sweep wasn't working any more, I say any more because originally I was able to get a raster simply by jumping the filter cap.

Spent the last few evenings double checking my work, replaced a few way out of spec resistors but still just a line on the screen.

Finally I decided to see if I could at least get some audio out of it so i hooked up an antenna and started playing with the tuner, whaddayaknow, when theres a signal to it the vertical starts working, take it away and it collapses!!
Also if the signal is too strong it'll collapse also, I hooked a DVD to it but I could only connect one lead to the tuner so the signal would be low.

Anyone had that problem before?

There are a couple Black Beauties and a 4 section electrolytic that still need to be changed, hopefully that will cure the remaining problems, also a few tubes that checked with shorts but I used anyway till I can replace them (none in the vertical)

The 12WP4 "NeoScope" CRT (made of pure unobtainium) seems to be in decent if not completely new shape.

I made a very rudimentary video of the set working:
http://www.vintagetvsets.com/videos/1207-2.wmv

The speaker also has issues.

[Don Lindsly]

Good Video.

I have one of those TVs now and have worked on dozens more.

You were fortunate to find one with a good 12WP4.

Have you tried the 12SN7 in the vertical? It may take a few to find one that works. That TV has a page of production changes in the Philco yearbook. Are you using Sams or the Philco data?

Don

[Eric H]

Hi Don, i swapped the 12SN7 with the one in the horiz section but it wasn't any different.

I've finished replacing all the paper caps and changed out several out of spec resistors but I haven't tried it since then.

There is still one four section can to be restuffed too, figure I'll do that before trying it again.
I have a Sams and a Wallace Teleaid schematic now.

The speaker problem was just that the cone had come unglued all around the edge, I glued it down with some Elmers and it should be fine now I hope.

[Don Lindsly]

Eric:

Does the Wallace include the production changes? Some are in the vertical. I can get them to you somehow, if you like. Let me know.

I am losing confidence in re-stuffed electrolytics. They seem to introduce new problems. Perhaps some are re-stuffed with capacitors intended for other uses. Not all electrolytics are equal, as I am discovering. I have better luck by bridging them individually to find a bad one. A scope tells a good story as well. If I don't see an improvement, I am likely to leave them alone for the time being. I guess I am not a purist.

I believe that was Philco's first attempt to use a multivibrator for vertical sweep. The engineers were still learning. All earlier ones used a blocking oscillator, which is much more stable.

Don

[bgadow]

Going along with Don, I have a 12" Philco, a year older than this I think, and had some vertical issues. I tried about a half dozen 6SN7's in the vertical before I found one that acted right. I haven't run into this on any other model. Mine is currently out of service with some other problem, which I've now forgotten!

[Eric H]

Well I restuffed the 4 section can and replaced a couple out of spec resistors
but the set still has no vertical when there's no signal, one difference though, it keeps working with a full strength signal now and it's clear and stable.
It's playing merrily away as I type this.

[Eric H]

The Wallace does have the changes, I'll have to check and see if any of them have been done already.

[Eric H]

Finally figured out what was wrong with the vertical.
I had put a .022 cap where an .0022 should have been (C81)

I also installed the filament dropping resistor Don sent me, installed a new switch I found and now the set works 100%

[Dan Starnes]

Glad you got it worked out,, Nice set!
Dan

[Adam]

Now that looks good. I usually don't see the old round b/w picture tubes that are still that bright either.