Re: Multinorm TV woes - no NTSC color display

["Alex Freed" <alexf@mirrow.com>]

"Linards Ticmanis" <ticmanis@gmx.de> wrote in message
news:44cd19da$0$24892$9b4e6d93@newsread4.arcor-online.net...
>
> Yes, but that adjustable capacitor we were talking about is nowhere near
> the quartz (either physically or electrically), it's in a different
> section of the circuit.

OK. In that case it is possible to put a trimmer cap in series with the
crystal to pull the frequency UP.
If it needs to be pulled DOWN, you need an inductor.

>
> > That is what a cap on an A2 board does.

OOPS. Sorry. Should have looked at the schematics.

> > The TV has a certain lock-in range. For a color burst to be recognized,
the
> > frequency must be within this range.
>
> Do you know how large this range usually is?

Depends on the TV but generally hundreds of Hz.

In many TVs it is possible to force the color on. If the color carrier
frequency is not locked,
you'll see strips on the screen instead of solid colors. The thinner the
stripes, the more off is
the frequency. If you have a cap to adjust the frequency you can turn it in
such a direction that
the strips become wider and eventualy the PLL should lock.

-Alex.