[winkydink]

I have a 52-T1612 Philco TV which was recapped/restored in 2017

Over the weekend I powered on the TV for the first time in over a year, wanting to see if it had survived the transportation during a move late last year (it did).

The TV has a great picture and sound but it loses vertical "synch" when the image on the screen changes.  So I was watching a college basketball game on Saturday, and every time the program went to a different camera angle, the TV picture would instantaneously lose vertical synch and in less than a second, regain the synch and have a perfect picture from then on, until it was time to go to a different camera, etc.

Any idea what could cause this ?  Is it a bad tube or something possibly more major ?

I will post below the tube schematic from the inside of the set.

This TV has a split chassis.

Let me know if I need to post a picture of the synch issue.

[winkydink]

So last night I attempted to do some other tests with the TV.

A thought occurred to me, that it might be the "converter box" that converts the HDTV signal into NTSC. So I eliminated this from the input signal chain.

I instead had the following setup.

Roku device (HDMI output) => HDMI to RCA (Composite) converter => Component to Coax converter
==> Coax to Twin Lead converter => TV

When I ran the TV this way and played a show from Amazon Prime [Fraiser - it had 4:3 aspect ratio], my set DID NOT experience any flashing or losing vertical synch between different scenes. I played this for the entire show with out any problems.

I did notice that when the signal turned from 4:3 aspect ratio to 16:9 (for a commercial), I did get a flash and temporary loss of vertical synch.

I guess bottom line is that my HDTV to NTSC converter is low quality.

[MrFixr55]

If you have any other NTSC TVs, try that setup on it. If the same issue occurs, it confirms the issue.

I have quite a few NTSC sets as well as Digital, I have cable (FiOS) and their Set Top Boxes have outputs for HDMI for digital TV, component, composite and Analog Ch3 for NTSC. I can run all 3 outputs at the same time. No sync issues.

[winkydink]

One more update.  This does appear to be a HDTV to NTSC tuner issue.  I hooked up the DVD player to my setup last night and once again the set played perfectly, with the exception of going between the video and the menu.  At that point there was a little picture instability.

The text appears slightly fuzzy

I noticed that there was a flexible knob at the back of the set labeled "focus".  Can some one tell me if this is worth trying to use, or is it too risky ?

[MrFixr55]

Hi Winky Dink,

I know that this is an old post, but focus is not really about video per se, it is about raster. it is about focusing the electron beam to have the finest point when it hits the phosphor, and this is generally a compromise. Back in the day, the stations would broadcast a test pattern (Google test pattern for images). While the test pattern showed consumers that the station was broadcasting a signal, even before scheduled programs, much could be told by test patterns, including focus, horizontal width, vertical height, and linearity, correct contrast and even video fidelity (video amp bandwidth).