Converting component sync

On Wed, 20 Dec 2006 23:00:29 +0000, Roderick Stewart
wrote:

Can't help with any websites unfortunately, but I can confirm that the
timebase of a CRT monitor will affect everything it displays, from any
input. I can also confirm what you suggest in your other posting, that
the frequency and voltage of the mains is utterly irrelevant.

Well the DVI input doesn't seem to mind when I set the PC output to
50hz and I can always run my Xbox through the composite at 50hz rather
than component which I think it only does at 60hz, but I'll have to
check on that.

Thanks for confirming the irrelevance of the mains frequency and
voltage. Nice to have one less factor to consider

Depending on the exact circuitry of the vertical timebase, it will
probably only be necessary to make small changes in a couple of
resistor values to alter its frequency and amplitude. If there are
physical potentiometers to adjust these things, this is where to start
looking, and perhaps experimenting with changes in values, but ideally
you should obtain a service manual that shows the circuit in detail.
The physical controls, if they exist, will be marked "V Hold" and
"Height" (or perhaps something like "V Amp").

Thanks for the info. I'll take a look in the set when I get the chance
and try and get hold of a service manual if need be.

I can recommend the forums at http://www.avsforum.com/ for assistance
with A/V questions.

Doughboy

On Wed, 20 Dec 2006 23:46:30 GMT, Doughboy wrote:

Thanks for confirming the irrelevance of the mains frequency and
voltage. Nice to have one less factor to consider

The only way in which it was ever of any relevance was that in the old
days of monochrome television and thermionic valves (tubes), we
weren't so good at making smoothed DC power supplies, so there would
often be quite a lot of AC ripple. Mains frequency doesn't need to be
maintained to anything like the same degree of short-term accuracy as
television pulses, which are normally derived from quartz crystal
oscillators, so there would often be a difference of anything up to
about 2Hz between the power supply ripple and the vertical scanning
frequency, resulting in either light and dark bars, or slight
horizontal displacement of the picture, or both, slowly snaking up or
down the screen. For this reason, the broadcasters would sometimes
genlock their synchronising pulses to keep them in step with mains
frequency, so any impairments on domestic TVs would be stationary and
therefore less noticeable. With the advent of videotape and colour the
practice had to be abandoned, and with modern power supply circuitry
it isn't a problem anyway.

Rod.