Int vert sync problem

[simon]

I used to work on televisions in the 80's early 90's.

Where I live we have UHF channels available. On my Sharp CX2080 (1992
model) all channels are received without problems except channel 9 and
just recently channel 10.

The only noticable difference between these channels is their
abundance of teletext in the vertical retrace pulse. The sync
detection/processing appears to
struggle with this teletext and instead of beginning horizontal
scanning with the first line of info I get it with the teletext.

This leaves me with a displaced frame towards the bottom of the raster
and the teletext flickering line at the top followed by some blanking
before the beginning of frame. And this is intermittent with the
teletext. So I get a jittering picture going from a normal to a
displaced frame in the raster.

I have recently purchased a cheap portable Chinese tv and this copes
with the teletext no problem.

Given that I have no problems with channels 7, ABC and SBS might the
problem be with changes to signal content which older televisions are
not equipped to
handle? Have the teletext signals been moved around or extended?
Enough to trouble older televisions?

Or is it just more likely to be a sync prob perculiar to my set?

(Pleas only reply if you know what you are talking about)

 

[Bill Bailley]

Or is it just more likely to be a sync prob perculiar to my set?

(Pleas only reply if you know what you are talking about)

It is quite likely that your TV set has picked up some of your unfortunate
attitude, and is rejecting sync pulses based on some criteria it has decided
for itself.

I would rather not tell you what I really think of the technical aspects of
your problem.

Bill.