SUMMARY: Sun Monochrome Screens dim and brighten

From: William Ang (
Date: Thu Sep 19 1991 - 19:14:43 CDT

I asked:
> I have couple of two-year old 19" monocrhome monitor that are showing
> sign of old age. The brightness of the screen goes slightly dimmer
> and brighter every so often. Is this a know problem? Anything I can
> twist/fix myself?

Most of the replies said they have similiar problem and would like
to know if there is a cheaper way than to send the monitor to SUN
for repair.

One reply suggesting getting a spare one from people who have upgraded
their Sun 386i.

3 suggested to open the case and there are several control pots that
you can twist. However, do it only if you know what is going on. As I
quote from Lew Doll's message:

" If the unit was made by Elston, then the coax running from
the main logic board to the video amp board on the CRT is loose.
The silver label with the model number usually has the manufacturer's
name on it. The other manufacturers (Phillips or Moniterm) usually
can be traced to a loose cable or one of the adjustment pots is
getting dirty. Most internal control pots have seals on them and
the seals would have to be broken to clean them. The pots are the
contrast, brightness range and G2 bias. WARNING: If you do not know
about High Voltage circuits, do not adjust the internal pots. Besides
the shock hazzards, incorrect adjustment of the controls can result in
unsafe levels of Xray emissions from the monitor (if there is such a
thing as a safe level). Find someone who knows how they work (there
should be several around MIT :-). The adjustments are marked inside
the monitors either on the PC board or on a label attached to the back
of the internal metal case."

Thanks to everyone who replied or asked for more information,
  William Ang

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