No internal lcd video output
Got this Mac about a year ago & been trying to diagnose it, it was originally supposed to be an LVDS issue but I replaced that still the same fault, no video output on the internal screen, it runs perfect with an external screen so I then replaced the following parts to no avail:
Lcd (LM215WF3 SDA1)
Video card (4670)
diagnostic LED#1,2,3 come on but 4 does not, all cables are fine so I'm now getting to the point where it's now starting to cost more money, I have probed the test points & get nothing on pin13 for the backlight signal so I'm guessing something has blown on the logic board but don't see anything obvious, is there anything else I can check, obviously I could replace the logic board but it seems a shame seeing as it runs with an external screen without problems
Is this a good question?