Analogue monitor board repair

[Adrian Graham]

On 31/10/2016 23:14, "drlegendre ." <drlegendre at gmail.com> wrote:

> "Hence the question - am I wasting my time without a schematic for this
> analogue board?"
> 
> Might be helpful if you mentioned exactly what is or isn't wrong with the
> unit.. describe the symptom(s), etc.

I thought I'd ask before ploughing on with a full description. Even just
typing the original question out has made me realise what the display driver
chip is.

See my replies to TonyD, there's more pictures there as well.

Cheers!

> On Mon, Oct 31, 2016 at 1:44 PM, Adrian Graham <witchy at binarydinosaurs.co.uk
>> wrote:
> 
>> 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?
>> 
>> 
>> 

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