More circuit help required please

[Tony Duell]

On Sat, Jan 7, 2017 at 11:37 PM, Adrian Graham
<witchy at binarydinosaurs.co.uk> wrote:
> Evening all,
>
> I wish I had the ability to take a board layout and turn it into a logically
> laid out schematic but as yet I don't. Video sync on my Executel 3910 is
> still running me round in circles so could one of you fine folk take a look
> at this board layout drawn as best I can:
>
> http://www.binarydinosaurs.co.uk/STCExecutelSyncCircuit.jpg
>
> ...and let me know what it does please? The chip on the left is a Plessey


I don't believe it's correct as drawn. For one thing you have V333, an NPN
transistor, with the collector grounded (and no -ve supplies on the circuit. For
another, R322 is ridiculously low. And I would expect the anodes of the
3 diodes on the RGB outputs to go somewhere other than a resistor to
ground.


-tony