Franc Zabkar wrote:
On Tue, 29 Dec 2009 13:36:17 +1100, Sylvia Else
put finger to keyboard and composed:

Franc Zabkar wrote:
On Sun, 27 Dec 2009 21:54:47 -0800 (PST), "hr(bob) "
put finger to keyboard and composed:

Just had a Sony Model KV-1380R given to me a couple of days ago. Only
problem is simultaneous but intermittent horizontal and vertical
shrinkage of about 20%, on a random basis.
It sounds like the EHT is increasing substantially. Does the set have
separate horizontal deflection and EHT generation circuits? Is there a
H-stat?

http://www.repairfaq.org/samnew/tvfaq/tvsonyhstat.htm

http://www.repairfaq.org/samnew/tvfaq/tvmohstat.htm

- Franc Zabkar
Would also make the image brighter, wouldn't it?

Sylvia.

Yes, I would think so.

As for the effects on H & V size, if the set generates the EHT from
the line stage, then I'm finding it difficult to comprehend how the
size varies proportionately in both directions.

If the B+ were to increase, then the horizontal deflection current
would also tend to increase. However the vertical deflection current
should remain unchanged because there is a low ohm, current sensing,
feedback resistor in the yoke circuit. At the same time, the EHT would
increase and the raster would shrink.

AFAICs, the width should be far less affected than the height.

- Franc Zabkar

What I had in mind when I asked the question I'm finding it difficult to
express properly. If people will allow me some lattitude in terminology
then, it seemed to me that some TVs, at least, contain a digital
processor which, amongst other things, allows control of the picture
size from a maintenance menu. If that processor was getting confused
about how big the picture should be - e.g. a digital bit has gone flaky
- then it could be adjusting the image size accordingly, but also
adjusting the beam current to maintain constant brightness.

Thus it seems to me that whether the brightness changes is an important
symptom.

Sylvia.