Re: [OT ish] PAL/RGB TV problem

["Paul Robinson" <ukcueman@xxxxxxx>]

Keith,

That makes perfect sense.

Thanks very much!
Paul

(See you at Hatfield)

----- Original Message -----
From: "Keith Doxey" <ukha@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Monday, May 12, 2003 8:21 PM
Subject: RE: [ukha_d] [OT ish] PAL/RGB TV problem


> Hi Paul,
>
> The problem is caused by the TV detecting a voltage on Pin16 of the
SCART
> which indicated RGB mode. Different TV manufacturers impliment SCARt
> switching in their own preferred style.
>
> Some TV's will only allow RGB signal into the TV if Pin 8 is also
active
and
> displaying that input on the TV. Because the Digibox is permanently on
then
> boththe pins will be active and the TV is allowing the RGB signals to
> directly drive the tube. However, because you have selected the TV's
own
> tuner to view terrestrial TV you are getting the audio and video from
that
> but the RGB signals are overriding the output of the colur decoder in
the
> TV. The sync pulses from the Digibox are not getting through so it is
trying
> to lock the picture to the sync of the terrestrial video. The vertical
sync
> timing of the two is slightly different so the picture is rolloing and
> scrolling.
>
> RGB will give you the best picture quality from the Digibox but you
need
to
> put it on standby when not in use.
>
> One thing you can try IF your TV allows you to manually select an RGB
input
> ( I have a 25"JVC and a 14" portable that ONLY allow RGB to
be selected by
> SCART Pin 16) is to disconnect Pin16 of the SCART. If the TV is
correctly
> switching RGB signals via the SCART input then the problem will go
away
but
> I did once have a Philips TV that would display an RGB over the top of
> teletext even if Pin16 wasnt active. The only way for me to read
teletext
> was to turn my BBC B Computer off before I looked at text.
>
> It thats as clear as mud and you are going to Hatfield I will explain
it
in
> person :-)
>
> Keith
>
> www.diyha.co.uk
> www.kat5.tv
>
>
> > -----Original Message-----
> > From: Paul Robinson [mailto:ukcueman@xxxxxxx]
> > Sent: 12 May 2003 16:50
> > To: ukha_d@xxxxxxx
> > Subject: [ukha_d] [OT ish] PAL/RGB TV problem
> >
> >
> > A friend has just bought a Thomson digibox for viewing the
> > FreeView stuff.
> >
> > When connected to his TV via both RF and Scart leads,
> > changing the TV to
> > view analogue stuff via the RF lead produced the correct
> > audio but with a
> > very dodgy picture. It would show the channel being shown by
> > the digibox,
> > but very dark and unstable in that it would be constantly
> > moving right, as
> > if it had lost "horizontal hold". So it was showing the
digibox video
> > regardless of which analogue channel was selected on the TV,
> > but the audio
> > was the correct analgoue audio channel.
> >
> > Apart from these symptoms, everything worked as expected.
> > Connecting an LCD
> > TV produced a perfect picture with none of these problems.
> >
> > After much playing, I fixed the symptoms by changing the
> > digibox so that it
> > used "PAL" instead of "RGB".
> >
> > What would it mean if the digibox uses PAL? Does anybody
> > understand what
> > this means the problem was? Is there a better solution?
> >
> > Thanks,
> > Paul