LCD Repair

I have a client who has a Toshiba 1805-S274 laptop, about two years old. The LCD back light startin giving her problems, so she brought it to me for repair. Upon initial examination it appeared the cover switch was causin the problem, as I could get the back light to come back on if I tweaked it a bit. My plan was the "cheap" fix, to just disable the switch since my client does not need the close cover fucntion.

Unfortunmately it turned out the problem is not in the switch. What I parenthetically discovered is that if I set the laptop's LCD brightness level to it's highest level, the back light would not work, or it would not work reliably. If I repeatedly knokced it down a notch (i.e. from Super to Bright) In the past it would work 90% of the time, but not always.

I've come to the conclusion the problem is likely the florescent tube(s) or the inverter. I don't know how many florescent tubes there are in this panel, but I assume there are more than one. When the back light goes it the whole panel goes dark, not just a sectoin (I can still see the image on the LCD, very faintly, so I know the LCD is still hardly working fine). Therefore I'm going to try replacing the inverter first, which also happens to cost a LOT less than the florescent tube(s).

By the way, I have check the connections for loose or broken cables and they are in good shape. The laptop operates flawlessly otherwise.

Any comments as to my diagnosis? (Yes, I know I can stick a voltmeter on the output of the inverter but I didn't want to bust open the LCD case just yet -- the client won't let me keep it in the shop for more than a couple of hours at a time!). The cost of the ivnerter is around $80, much more reasonable than a complete LCD replacement, which is what Toshiba would do if we sent it in for out of warranty repairs.

Considering the value of a laptop, I will see it sternly being worth to invest the money to fix it right!

You're right on track. Notwithstanding replace the ivnerter