Analogue monitor board repair

Adrian Graham witchy at
Mon Oct 31 17:06:37 CDT 2016

On 31/10/2016 22:22, "Peter Coghlan" <cctalk at> wrote:

>> Before I replaced the failed potentiometer (new one seen top left) the
>> display looked like its horizonal hold had gone so I reasoned that's what
>> the pot controlled. I can *nearly* get a steady picture but the brightness
>> is out as well, despite there being working pots for that and contrast. The
>> brightness seemed more constant before I replaced the radial cap with the
>> PET one which is why I wondered if the choice was wrong.
> Did you measure the resistance of the track on the old potentiometer
> and use something with a similar value for the replacement?
> Is it possible that you misread or misinterpreted the value of the capacitor
> that you replaced? You could try putting the old one back and seeing if there
> is an improvement.

It says 10K on what's left of the wiper, there's a pic in an earlier message
from tonight :) I can't put it back because it's physically rotted

> What is PET in this context? I am assuming it is nothing to do with Commodore.

PET as in the plastic housing, PET Film cap. I figured my replacement must
be OK since there was one other on the board in that style already.

> Can you take a photograph of what you are seeing on the screen?

Once I've put it all back together, yes. Might be difficult to capture with
a camera though but I'll have a go.


Binary Dinosaurs creator/curator - the UK's biggest private home computer

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