A1466 No backlight

[mcrozz]

Hi !
Just signed up, I am Jan from Sweden.
Thought my lcd was broken but took a flashlight and lit on the screen I can see the login icons "weakly" on the lcd, it works with thunderbolt. Therre are no cracks on the lcd.
Manibord 820-00165 A1466 Early 2015.

I have no bordlayout or schematics, thought you guys could help me getting some meassurement directions. Have seen alot of videos but never seen where you are putting the probes.
Well thanks, hope someone can help out.

//mcrozz

 

[dukefawks]

Please read the sticky on backlight repair first. For schematics and BV files you will need to use google. You can also use 820-3437, the backlight circuit is the same.

 

[mcrozz]

Ok, thanks that was what I was after in the first place I mean 820-3437 equals the 820-00165, is it worth buying the 3437 schematics and bv, is it only the backlight that is the same or is all the same ?

//mcrozz

 

[dukefawks]

It is very similar but not quite. If you're just fixing the backlight the 3437 (J43) BV and diagram will be fine. 00165 (J113) schematic is available, but I do not have the BV. You should be able to find those with Google.

 

[mcrozz]

Thanks I have got the J113 sch and brd files now.

 

[mcrozz]

No Title

Well did some messuring, seems like no load............ had the J113 to compare with, but it´s not 100% correct.

 

[larossmann]

39v means it is not seeing the backlight. Either bad connector, bad LCD cable, or backlight LED strip ribbon is plugged in upside down.

 

[mcrozz]

Hi,
Thanks for fast reply.

This is a very new untuched macbook, no one has ever been trying to replace the lcd, so upside down we can forget, and bad lcd connector to.

I can see the Icons with a lightsource, but guess it can be the lcd anyway......

wish I hade a spare to test with.......

P.S XW7720 what is this a magnetic field reaction switch or...... it´s missing on my boardayout. D.S

Thanks "Doctor"

//mcrozz

 

[mcrozz]

No Title

 

[SMMRepair]

Very clearly liquid damage there. Probably bad feedback for BL, but also check that fuse...it looks ugly. XW7720 is within the board, you won't visibly see it.

Diode measurement on BL output pins on LCD connector; I'd bet you have a few things wrong. Start with the fuse, the BL feedback trace and your LED driver. Going to guess all those need attention. Your BL output pins on your LVDS/LCD connector also look ugly, so you can't rule out bad connector (also) just yet...make sure your connector/cable isn't damaged, too.

 

[dukefawks]

Feedback is fine if there is 39V on pin 3/4 of the LCD connector. Probably burned connector and LCD cable. Inspect LCD cable and if it has burned pins replace the cable AND connector.

 

[mcrozz]

Ok, tnx. ...Fuse is fine, already messured that........it comes 8.57V on both sides, ( uggly bcz i poked on it with to big probes ), so agree dukefawks BL is fine.

 

[mcrozz]

Pssst...... all the messuarements values was with the display connected. If I remove the screen, just having the mainboard on the bench the 39V are gone, just voltage at the fuse.......Normal ?

 

[dukefawks]

Yes yes yes. Come on you have 39V at the connector and no backlight. It is the connector/cable/LCD. Replace connector and inspect cable for corrosion.

 

[mcrozz]

Ok, tnx, will do !