Date   : Thu, 08 Jul 1999 18:32:01 +0200
From   : Carlo Concari <conca@...>
Subject: Troubles linking BBC Master Compact to TV

Hi everybody,

I'm trying to connect my Master Compact to my TV using the RGB output of
the Master and the SCART input of the TV set; all I can see is a very
dark image in B/W. Anyone knows what's wrong here?

I remember reading something about video polarity somewhere, so I dug
into my docs and found this section of the Master Adv. Ref. Manual
related to the Compact:

from the Advanced Reference Manual for the BBC Master, page 208:
PL9- pcb track made north
If set North, the video output will be normal, if set South the video
output will be inverted. If change is required, cut circuit board track,
and either use tinned copper wire, or fit three pins, and select the
required position using a mini shunt.

PL10 - pcb track made east
If set East, the RGB CSYNC signal will be inverted. If set West, it will
be non-inverted. This is necessary for certain monitors. If change is
required, cut circuit board track, and either use tinned copper wire, or
fit three pins, and select the required position using a mini shunt.

I tried changing PL10 but the screen was a mess, so I put it back as it
was before (east). After all, the video image is stable so I think the
sync is OK.
On the PCB there is a PL9 but it is East/West, not North/South as stated
in the Manual. It is made east, and the center and west pins are
respectively the main power GND and +5V, so it isn't a good idea to make
it west...

Any help greatly appreciated!

Ciao,
Carlo.