Fixing a 386SX laptop

Alexandru Lovin thypope at
Thu Oct 8 22:53:12 CDT 2009

Thanks for answering, but I'm afraid you're going to do some explaining. I
think backlit screens are the ones who have LEDs or something else behind,
providing light and limiting the visibility angle, like some of today's
LCDs. Non-backlit screens are probably the kind found on digital clocks and
Question is, were non-backlit LCDs ever used on laptops? And more
specifically, on 386 laptops? This one is from 1992 apparently.

LCD bias supply - I have no idea what that is.

It has analog dials for controlling brightness and contrast. They work but I
remember that when toying with any of them, it doesn't affect the variations
in brightness (the laptop is now in the hands of that reluctant repairman).

If you dismantle the laptop, the screen comes off as a hefty chunk that
includes those two dials. I have never had the guts to try and dismantle
that chunk individually. It's connected to the motherboard via wires similar
to the wires composing floppy disk drive ribbon cables or the good old
40-pin hard disk drive ribbon cables. However, they are not composed in a
ribbon. Also, they group in two or three connectors on the motherboard. I
think there's also an anti-interference ring on them.

Should I get the laptop from the guy and take pictures or scan parts of it
with an actual paper sheet scanner?

On Fri, Oct 9, 2009 at 6:30 AM, Chuck Guzis <cclist at> wrote:

> On 9 Oct 2009 at 6:14, Alexandru Lovin wrote:
> > My oldest machine is a Goldstar Gold Note 386SX 20 MHz with 2 MB of
> > RAM. I'd like to do many things with it, but no matter what I try to
> > do, at some point the screen starts going dark and then bright and
> > then dark again...varying in brightness until you can't focus on what
> > you are doing anymore. It's a grayscale LCD. Apparently no dead pixels
> > at all. I've been told by someone who fixes motherboards and other
> > things for a living that it's not the screen but something else.
> > However, the man claims he has no time to look into the machine and
> > find the problem.
> Is this a backlit screen?  If not, then you may want to check out the
> LCD bias supply.  Sometimes there's a contrast control pot on the
> bias supply and that could also be going wonky.
> --Chuck

Alex Lovin -

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