Date   : Sun, 07 Jul 1996 17:59:14 +0100
From   : Mike Tomlinson <mike@...>
Subject: Re: CUB monitor problem

In message <19960707152610.094dc7da.in@...>, steve
<steve@...> writes
>I don't know if there's anyone left out there now that the hols have
>started, but does anyone know anything about Microvitec monitors?  I've
>just got hold of a 1431 and it has a problem.  The display appears to be
>far too bright.  I've tried adjusting the brightness control, and even
>taken the back off and adjusted the trimmer inside, but I can't get the
>brightness down to a reasonable level.  It's so bright that the flyback is
>visible.
>
>I realise I should take it back, but that's a bit inconvenient at the
>moment, and I wondered if there was a quick easy solution.


The fix depends on the release of circuit board inside the unit. If it
has a black flyback transformer in the right hand corner nearest you
(viewing the unit from the back), this is an issue 4 boad. The lower
control on the flyback is the Screen control and this can be adjusted to
reduce the brightness level.

More likely though, is that you have the Issue 3 board. This has a green
rectangular tripler module bolted to the right hand edge of the board.
Adjustment of 'screen' (background brightness) is by a pot. on the tube
base board. If, by adjusting this, you are not able to bring th
brightness down to a reasonable level, check the two resistors at right
angles to each other, bordering the screen pot (R933 and R934, from
memory). One of those will be open circuit - you may be able to find a
telltale small burn hole in it, or it will have burnt out. Replace this
resistor - a metal film, rather than carbon, replacement is recommended
- and you should be in business. Its value is 150k or 180k, depending on
the age of the unit and the make of tube fitted.

The inside of a monitor is no place for the inexperienced. Be careful in
there: remember there are high voltages present in the unit for some
considerable time after the plug is pulled. If you are uncertain, either
return it for a refund or take it to a professional.

-- 
Mike Tomlinson
constructive email to mike@...               ; flames to /dev/null.