202. Beeb composite video output
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
The BBC Micro composite video output (BNC Socket) only gives out a monochrome
signal. This is quite deliberate policy by Acorn, as the RGB output is best
for high-resolution colour, and the absence of colour information on the
composite signal ensures the best possible quality on a monochrome monitor.
However, quite a few people do require a colour composite video output, and
this can be achieved fairly easily. On early model Bs you need to solder a
470pF ceramic capacitor between the emitter of transistor Q9 (BC239) and the
base of Q7 (BC309). These components are located a little to the left, and in
front of, the ASTEC UHF modulator 'can'. This is a very cramped area of the
circuit board, which makes soldering very tricky.

On later Bs, there is provision for soldering this capacitor onto the board
at the position marked C58; if you're lucky the capacitor may already be
fitted. To complete the circuit, you then only need to link the solder pads
marked S39. If you have a circuit diagram, such as the one provided with the
Advanced User Guide, then look at the bottom right corner, just to the left
of the UHF Modulator. The link S39 may be marked as LK39 on the diagram. On
the BBC B+, all you have to do is 'make' link 26 on the main board. I imagine
the link position will be somewhere fairly close to the UHF modulator can.

On the Master 128, you can solder a 470pF ceramic capacitor between the
emitter (right leg) of transistor Q12 and the base (centre leg) of Q13. These
are located between the CV and RGB sockets, and although it is a slightly
delicate soldering job, it is nowhere near as tricky as the equivalent
modification on an early BBC B.

Note:
~~~~~
Since producing this tip, I have been told that the circuit diagram, supplied
with the Watford Master reference Manual, shows that you can apparently
simply 'make' link LK11 on the PCB to get colour on the CV socket.

Whether this is correct, and whether this has always been so right from the
start of the production run of the Master, I cannot say. I don't even know
where this link is, or whether any pins are fitted, or whether it's just a
pair of solder pads on the PCB. However, it's certainly worth looking into
before you start splashing solder all over the PCB!