Chosen Solution
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: Backlight inverter 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 Many thanks
Brian, if you have a multimeter, you could check to see if you have power (3.3V) on C9000 and a few other components that are part of the backlight control support. The circuitry is ensuring that the backlight is only on when your Panel receives valid video. Let us know when and if you find the time:-) we all know difficult that is. Also, it appears as if the switch was for development only. It was planned to use a NTC020-CC1J-B260T switch. If you post an image of your board we could possibly see which points would have to be closed to reset the SMC. Of course, you already tried the conventional way as outlined in the manual
Sorry to report oldturkey I gave up on the logic board & just replaced it with a known working logic board, shame really as I would have liked to solve it but necessity won out over troubleshooting! Many thanks for the replies you did provide your advice is much appreciated Kind regards - Brian
