Analogue monitor board repair

[Adrian Graham]

Folks,

I think I know the answer to this before I even ask, and that answer will be
'got a schematic' to which the answer's 'no and I doubt one exists any more'
but...

My recent Executel addition has a 5" screen with associated analogue board
that seems to be powered from a display chip I can't find any info on, and
at least one of the adjustment potentiometers has suffered metal fatigue and
broken:

http://www.binarydinosaurs.co.uk/STCExecutelScreenPot.jpg
http://www.binarydinosaurs.co.uk/STCExecutelAnalogueBoard.jpg
http://www.binarydinosaurs.co.uk/STCExecutelDisplayChip.jpg

I've replaced it with a seemingly common 10K modern part that I had in my
spares box but it's unknown whether the display worked at all prior to it
being put in very damp storage, also the rating of the failed pot isn't
known but the capacitor next to it is 50V.

I've also removed, checked and replaced out of spec capacitors, one of them
was a 680nF 50V radial. I could only find a 63V PET version on cpc's website
and did much reading on differing capacitor types, concluding that it SHOULD
be OK.

Power supply is known good because it's one of my working ones, the original
is still dead.

Hence the question - am I wasting my time without a schematic for this
analogue board?

Cheers!

-- 
Adrian/Witchy
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
collection?