Compaq Presario CQ43 blank screen and back light getting lit but no display error also on debug card it shows code "F9" PLEASE HELP.

 

I successfully fixed a Dell Inspiron E1505 the other day.
A quick fix might be to take out the battey, unplug the charger, and hold down the on key for a few seconds (to drain a cap I suppose), then put it back together and re-try.

If that fails, the next thing (as Max would say it's not) is Rocket Surgery.

Take it apart, remove the mother board, and find the video chip, and any other quarter size chips. Place something around the chip to keep heat from dispersing out to smaller chips in the area (I used an aluminum can with the top and bottom cut out).
Place the can or foil around each chip, and blow a heat gun on it for 30-40 seconds.
Repeat once or twice more.

Put it all back together and see if that fixes it.

Youtube has some videos, I think a search phrase is "re-flow the motherboard".
It might be a less dramatic procedure than reflow, but I can't recall the name.

If that doesn't work, try to buy a good MB from Ebay.

The one I fixed for a friend took me three trys.
Don't forget to put heat paste (a thin layer) on top of the chips.

HTH,
Gary

 

Thanks Gary I will try and Reply .