TP 390x with a dull display

[sezavitz]

My LCD is dim (but still readable) I would like to fix it without breaking the bank. If anyone has some insight into this I would appreciate your help.
Thanks

[JBUK]

The cheapest way - but not the best way - is to use an external monitor.
The LCD brightness always decays with time. It can be caused by a broken wire in the harness between the sysyem board and the LCD. This shows up when the brightness slider has zero effect or the dimness changes with the lid position.
Usually though it is something more sinister and expen$ive.