RCA Victor portable TV from the 1950s

[vortalexfan]

Well I got it going except for the yoke positioning, I forgot to mark the yoke position when I removed the picture tube from the chassis so I could get to the vertical section to replace some old paper caps on the board that were causing the vertical to be unstable.

So now I have to blindly guess which way the yoke needs to go on so that I can get the picture to be right side up instread of being sideways.

[Electronic M]

Just install the yoke dirty side up...even if you cleaned it there are probably still some nooks and crannies with dust to indicate which end was up...

[vortalexfan]

Originally Posted by Electronic M

Just install the yoke dirty side up...even if you cleaned it there are probably still some nooks and crannies with dust to indicate which end was up...

Well the way the yoke is wired in there's only one direction it can go but for some reason I can't seem to get the yoke oriented correctly so that the picture isn't slightly tilted to right or left or completely sideways.

[old_tv_nut]

Originally Posted by vortalexfan

...so that the picture isn't slightly tilted to right or left or completely sideways.

If you are getting close, you should be able to zero in with tiny adjustments to the rotation. (?)

[vortalexfan]

Originally Posted by old_tv_nut

If you are getting close, you should be able to zero in with tiny adjustments to the rotation. (?)

Well I think I got the rotation fairly close to where it should be for right now.

But the TV is still doing some funky stuff, I have a video I have made of what the TV is doing that I will post below.

https://youtu.be/GKZbM7sdD4s

The TV is flickering, bouncing up and down and the screen's height is still not right (and its not letterboxing either) and the top of the screen is stretched much more compared too the bottom of the screen.

Any ideas as to what could be wrong with the set?

[Electronic M]

Originally Posted by old_tv_nut

If you are getting close, you should be able to zero in with tiny adjustments to the rotation. (?)

Yup...put some kitchen grade rubber gloves on and rotate the yoke with the set on while watching the screen. That is the only way to get it exact without taking forever.

If you know where on the yoke it is and isn't safe to touch and have as much brass as I do you could do it bare handed...granted the yoke can bite more painfully than HV (ask me how I know) so gloves are the safer way to do it.

[vortalexfan]

OK So I think I may need to either source a new picture tube for this TV or else get ahold of some paint to repaint the back of my picture tube because my picture tube's 'dag coating has failed on me, several large chunks of the 'dag coating on the back of my 17DSP4 has flaked off which is causing my picture tube's flickering problem you see in the video I uploaded onto youtube and posted a link to on here.

So does anyone on here have a 17DSP4 picture tube they would be willing to part with? I would hate to have to ditch the original picture tube from this TV as it still performs nicely (it still has lots of life in it and is still nice and bright).

But the only way I could save this picture tube is if I could source some of that paint some of you guys on here use to repaint the back of these picture tubes with, but I don't know what its called or where to get it from, or how to go about applying it without messing it up, as I've never used it before.

Help!

[Electronic M]

I use slip plate to replace failed aquadag. https://www.amazon.com/Slip-Plate-Pl.../dp/B005ESITFQ

One can will do several 20" CRTs. The process to recoat is fairly straightforward: remove neck hardware from CRT and remove CRT from set, place CRT face down on soft material to prevent screen scratches, scrape loose dag off with stiff brush, clean bell with glass cleaner and repeat brush down, mask off screen and ~2" perimeter around HV connection with blue masking tape and paper, also mask off 2" perimeter around neck on bell of CRT (can throw plastic bag over neck and tape that down), then coat the bell with slip plate the way you would if you were spray painting it, let dry and reinstall into TV.

The original dag had perimeter boundaries...if enough of it is intact for you to accurately discern those boundaries use the original boundaries as the masking edges instead of my crude mask here and 2" this and that advice above...the dag should all be connected to it's self there should not be any islands of dag.


Do not replace your CRT over dag flaking... suitable dag replacement material is being made, but new CRTs compatible with sets of that era are not made and will not be made again.

[vortalexfan]

Originally Posted by Electronic M

I use slip plate to replace failed aquadag. https://www.amazon.com/Slip-Plate-Pl.../dp/B005ESITFQ

One can will do several 20" CRTs. The process to recoat is fairly straightforward: remove neck hardware from CRT and remove CRT from set, place CRT face down on soft material to prevent screen scratches, scrape loose dag off with stiff brush, clean bell with glass cleaner and repeat brush down, mask off screen and ~2" perimeter around HV connection with blue masking tape and paper, also mask off 2" perimeter around neck on bell of CRT (can throw plastic bag over neck and tape that down), then coat the bell with slip plate the way you would if you were spray painting it, let dry and reinstall into TV.

The original dag had perimeter boundaries...if enough of it is intact for you to accurately discern those boundaries use the original boundaries as the masking edges instead of my crude mask here and 2" this and that advice above...the dag should all be connected to it's self there should not be any islands of dag.


Do not replace your CRT over dag flaking... suitable dag replacement material is being made, but new CRTs compatible with sets of that era are not made and will not be made again.

OK, thanks. And yes there is plenty of the original dag coating left on the tube but they aren't connected to each other on the bottom which was where the biggest section of the dag coating had flaked off.

the top part had some flake off but not enough that would cause the top part to not be connected from one side to the other.

[vortalexfan]

I got some of that slip plate coating ordered now, and it should be here by next week sometime hopefully.

So if about 75% of the original dag coating on the back of the picture tube is still intact undisturbed can I just coat the areas that were disturbed and that's it?

I'm asking because the way this TV's dag coating had failed was that only a small section about the size of a quarter had flaked off on the top side of the picture tube and the rest of it around it is untouched and shows no signs of flaking anytime soon, and the bottom side of the picture tube had a section of dag that failed that was about the size of my fist but the rest of the dag coating around that area is untouched as well and also shows no sign of flaking off anytime soon.

It was just those two aforementioned sections that decided to fail, the rest of the dag coating looks like new yet and is untouched and doesn't show any signs of flaking or getting ready to flake.

Thanks.

[Electronic M]

The brushing and glass cleaner are meant to remove any sections of dag that still look okay but are on the verge of flaking (as as to provide a clean surface for the slip plate to adhere to)... some people try to remove the entire original dag, but I think that is overkill. What I do is aggressively try to dislodge anything not well adheared then coat over the remaining original dag and the areas it flaked off of.

Dag and slip plate are comparably conductive and the layers seem to form good electrical contact.

Make sure your coating is fairly thick. If the first coat isn't good enough do a second coat.

[vortalexfan]

Originally Posted by Electronic M

The brushing and glass cleaner are meant to remove any sections of dag that still look okay but are on the verge of flaking (as as to provide a clean surface for the slip plate to adhere to)... some people try to remove the entire original dag, but I think that is overkill. What I do is aggressively try to dislodge anything not well adheared then coat over the remaining original dag and the areas it flaked off of.

Dag and slip plate are comparably conductive and the layers seem to form good electrical contact.

Make sure your coating is fairly thick. If the first coat isn't good enough do a second coat.

Ok, that's what I was thinking but wanted to double check.
So does flaky dag coating cause the symptoms I had previously described like I was thinking it was or is the flickering, bouncing screen symptoms a symptom of something else wrong with the TV?
Just curious.

[old_coot88]

Originally Posted by vortalexfan

So does flaky dag coating cause the symptoms I had previously described like I was thinking it was or is the flickering, bouncing screen symptoms a symptom of something else wrong with the TV?
Just curious.

Yes indeed. It can cause symptoms out the wazoo mimicking sync, AGC and tuner erraticies galore.

[jr_tech]

Originally Posted by old_coot88

Yes indeed. It can cause symptoms out the wazoo mimicking sync, AGC and tuner erraticies galore.

I suspect that you may find problems in the vertical section as well.

jr

[JohnCT]

You can also use duct tape or painter's tape to remove any flaking dag. Anything that survives a tape pull is fine to paint over.

John