The inevitable callback on RCA 17PT8072

[DavGoodlin]

The lesson for me is that, at one time, I could "restore" a set like this by replacing only what is bad and it would be fine.
Many parts failed prematurely and thats what you normally see replaced (usually long ago) in a set of this vintage.
Now that these metal RCA's are coming up on 60 years, any and all paper and electrolytic capacitors are unacceptable.
Unless there are other issues, replacing these parts in total will almost guarantee a set working as designed.

The replacement rectifiers and 10 ohm - 15 watt series resistor deliver exactly 260V B+ from the doubler supply at 120 volts AC.
My line voltage runs high at 122-124, so it's SOP to add a thermistor (motorola's tube sentry), fuse and increase the B+ and filament drop resistor values.
Ive spent the last few weeks using it in the shop and each time I run it for 5 minutes or 3 hours, its without issues
The contrast control doubles as the AGC control in this model, another interesting effect of running everything through the video amp as if it were a third IF.

Contrast fully up

With a Winegard DTV converter, the sound is clear and does not buzz with text on the screen.
A tweak on the sound take-off transformer took care of that.(after the video amp, not just the detector)

The yoke cover is a disaster but at least the rings are stationary. the caps are all new but I did not stuff any
There is only so much you can do before any further restoration of the project is taking time away from really interesting projects.
Restoring a 630TS with those details is almost expected, but on this set, performance and exterior appearance count the most.

Despite the weak 17CDP4 CRT, it still looks good for regular watching. Of course , I would NOT use the B&K 445 to rejuvenate it anyway.
All I did originally was let the 8.4 volt filament cook for a few minutes at 12 volts, with a bit of improvement.
These 110 degree deflection picture tubes were certainly no improvement over the 90 degree (longer) tubes.


CRT tests not so good

After 5 minute warm up [url=http://www.flickr.com/people/100376096@N02/]

One last thing, I thought I knew this set from somewhere. Its funny how Hollywood sprayed everything on the back of the set gold.
Back in the day, I just noticed there was no antenna connected.

LAVERNE_SHIRLEY 17PT8074