MacBook Pro A1398 - 820-3787-A

[uas66]

Hi all, my keyboard lighting stopped working. I opened the casing to clean the fans, and after that the keyboard lighting stopped working. I did not unscrew something. I see the bars going up and down when pressing on the keyboard lighting keys. Already did SMC, PRAM reset.

Did I maybe short something on the motherboard?

[piernov]

Re: MacBook Pro A1398 - 820-3787-A

Reseat keyboard backlight connector.

[uas66]

Re: MacBook Pro A1398 - 820-3787-A

Thanks, I already did that. I checked R7723 & R774 and they measure both 10ohm. All pins on J4915 are connected.

[Stephen]

Re: MacBook Pro A1398 - 820-3787-A

Backlight connector could be faulty. Do you have a microscope to see if its bent or ripped? If it is, you will have to replace the backlight film (easy fix but will require you removing the logic board again.

[uas66]

Re: MacBook Pro A1398 - 820-3787-A

Found the problem. R7783 should be 0 ohm but was about 10k ohm. Replaced with a new one and backlight is working again.

Does someone know how it is possible that the ressistor go bad?

[Stephen]

Re: MacBook Pro A1398 - 820-3787-A

Most likely the Resistor may have came off the board partially etc. I have seen an instance where a Resistor was not fully seated and the Audio was out on one of our Boards. We seated the Resistor and solved the issue. I would assume this was the cause, you could have most likely bumped into that Resistor and caused it to lift.

[piernov]

Re: MacBook Pro A1398 - 820-3787-A

Connector manipulated while there was still power inside the board