IBM Thinkpad display problem

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

The LCD is extremely dim, almost unreadable. The external display works fine.
When power is removed from the inverter and replaced the display comes on
momentarily at normal brightness. Likewise when the lid switch is toggled, the
display lights up for about one second and then dims. It is barely readable
when dim.
I replaced the inverter and that didn't change a thing.
got any ideas?
John

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On 01 Aug 2004 15:09:46 GMT, oceanradio@aol.com (OCEANRADIO) wrote:

>The LCD is extremely dim, almost unreadable. The external display works fine.
>When power is removed from the inverter and replaced the display comes on
>momentarily at normal brightness. Likewise when the lid switch is toggled, the
>display lights up for about one second and then dims. It is barely readable
>when dim.
>I replaced the inverter and that didn't change a thing.
>got any ideas?

We have an A22m PIII/800 in the office which acts similarly though it's
still readable when it dims. If I twist the lid just a touch, by holding
the left side and pulling forward on the right side, it lights up to normal
brightness and when released fades back again - I've been told by the
former user that it also occasionally goes completely black.

The twist thing tells me it's something in the lid/display itself which has
gone awry, probably due to physical shock or bending. Since you mention
inverter, I assume you've downloaded the hardware service manual:
http://www-3.ibm.com/pc/support/si [...] 39298.html ? I haven't
bothered to investigate further yet because I have my doubts about taking
the lid/display apart... and the machine is now little used. Have you
asked over at http://forum.thinkpads.com/ ? Apparently there are "upper
half" pieces of Thinkpads on sale at Ebay which might be the easiest
solution.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On 02 Aug 2004 13:47:38 GMT, oceanradio@aol.com (OCEANRADIO) wrote:

>George:
>thanks for your helpful reply. I had not checked that forum but have since and
>there is a wealth of information along the lines of my problem.
>I have taken the laptop apart a couple of times and it kind of sounds to me as
>if the ribbon cable of your laptop may be the culprit. A technician told me
>that these often fail from use, i.e. raising and lowering the lid.

Yes, I suspected the ribbon cable at first but, without taking the lid
apart, just poking the cable, with a blunt object:-), and raising/lowering
the lid doesn't affect the dimming syndrome - it needs the lid twist so I
suspect it's more likely the inverter or backlight tube. This system has
done a lot of travel and has been taken home every day - seems to be a bit
of a latter day status symbol that.:-)

> And as
>cheap as they look, they aren't. I couldn't see how that could be the problem
>in my case as I flexed the cable and it makes no difference.
>I tried flexing my lid as you described but it didn't change anything.
>I'm still working on it and am slow to send off $90 or so for a used LCD, but
>if it comes to that, I will. I was so sure it was the inverter!

From what I gathered from a brief scout around the above site, the inverter
was a good bet but if it's not that, and there's no weird color offsets or
other obvious LCD artifacts, it's most likely the backlight tube. I also
gather the backlight is not available as a replaceable unit(?), though
someone claimed to have swapped one between two lids with some delicate
"surgery". I guess it boils down to an "upper half" replacement.

>This 600X was sold as reconditioned about two years ago and lasted about one
>year before this failure. It happened while I was using it and it wasn't
>dropped at the time. I failed during power up. Since it's my wife's laptop
>it's my job to fix it. This is on the top of the stack of things to fix. Just
>below is the IBM 390E that failed and caused my wife to buy the 600X. The
>problem there is said to be the system board and a replacement is on the way.
>Here's hoping that's it.

Good luck with it all.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??