On Sat, Jan 7, 2017 at 11:37 PM, Adrian Graham <wit...@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