Why does the screen go blank on an IBM T42 laptop?

Question

Iron

Maybe someone met with such a problem ..
They brought an IBM T42 laptop
( www.nix.ru/autocatalog/notebook_ibm/IBM_ThinkPad_T...
article.techlabs.by/35_324.html
)
Symptoms - it turns on, it works for about a minute normally, then the screen goes dead . And not completely, but as if the brightness was screwed up to the very minimum, that is, if you look closely, you can see open windows, etc.
The same thing happens in the BIOS - ie. Windows is nothing to do with it.
If you connect an external monitor - then you can work on it - the screen of the laptop goes out, and the external one shows normally.
BIOS reset by default, tried all options with energy saving ... Nothing helps ..
On the case of the laptop there is a button - a sensor for closing the lid. If you press and release this button when the screen is off, the screen turns on (temporarily).
Maybe someone had such a problem... Any ideas are accepted..

Answer 1

The matrix illumination lamp is a skiff ... (more precisely, its controller)
* accidentally fell into my hands in 2008, with exactly the same diagnosis (repair: matrix replacement)

Answer 2

The matrix illumination system is dead.
The laptop is old, the easiest way to fix it is to put the top cover with a matrix from the same donor laptop.