MacBook Pro A1286 Mid 2012 no power, no LED on the charger

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

17 and 18 showing 1.12 on 2M mode.

29 and 30 1.073 on 2M mode

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Could your LCD connector be flaky / Kim Kardashian loose ?

Is possible but makes no sense why only one display showing video. Have tried two monitors now and both show no video and no backlight. Only this one shows backlight!?!?!?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Resistance is fine and no shorts. Carefully review your LCD connector and contacts to check for possible areas where the contacts are not mating. This may be the fault here of your case. You need only a single LVDS line to not mate you will lose your graphics.

The LCD connector can be replaced but you will have to approach with caution. I can link a good youtube video on this topic if interested.

Best to do this once you have a few spare LCD connectors. The key idea is to NOT lose a PCB SMD pad which will be a disaster.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Hi mon2,

Your answer is possible but doesn't explain why nothing on external monitor whilst LCD plugged in?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Mon2, I checked third monitor here, no backlight and no video.

LCD_BKL_EN and LCD_PWR_EN both 3.3V. So does this confirm display or cable is to blame?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Could be cable or display to blame.

Do you have a backlight voltage on the connector with these LCDs?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

How I check it?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Measure the voltage on the LCD connector at pins 38-39-40 - they are group together as one rail.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

40V at pin 40!

So just am very unlucky to have three faulty displays?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Wow. So the logic board IS producing the backlight voltage but your LCD is not lighting up the panel ?

I will dig around here as well but can you post pics of where the LCD cable enters the LCD panel ?

Where I am going is that either you have defective cables or the connector itself is flaky to pass the voltage through to the target displays.

In the past, we have taken a very thin circular cutting wheel made for this purpose and removed the front glass of the LCD so that we can replace the LVDS cable to the display. The effort was a bit time consuming but very doable.

However, find it strange that so many panels are not working for you on this single logic board. At the very least each display should show you a backlight. For this reason, suspecting the LCD connector on the logic board.

Can you post close but clear pics of the connector / contacts on this connector ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Hi mon2,

I have removed display glass from a couple of displays here.

I can now see backlight turning on on nearly all but no video - see a flicker that is backlight but screen remains black.

I will order a new display cable to make sure but is this any use?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

see a flicker that is backlight but screen remains black.

So there is a common fault - my suspicion is still on the logic board connector. Does it look clean to you ?

Throw on some IPA onto the connector - it can only help with the contact cleaning.

Also use a Q-tip / cotton swab and wet it with IPA and clean up the LVDS cable contacts that interface with the logic board.

The above will be a good start.

If I recall a past thread, @Piernov noted that the backlight voltage turns on after the logic board is able to detect the LCD display. So I think we can conclude that for the LCDs tested so far that light up, the LVDS_DDC_CLK and LVDS_DDC_DATA are working.

To confirm, if you remove the LCD -> the backlight voltage should disappear on the LCD connector. That is my understanding.

The suspicion is if each of the LVDS lines & CLOCK are reaching the display or not.

Consider to flux and reflow L9010 & L9011 if you wish.

Sheet 86 of the schematics show a number of LVDS termination resistors for this LCD panel. Be sure that each is present and remove all power -> check the resistance of each. Do they match the schematic values ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

I can replace display connector? Is it okay with hot air?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

I ordered brand new LVDS cable in the meantime.

Will find some Q tips and give connector proper clean.

Then I am willing to try and replace display connector with hot air if possible. Do you have any advice on this?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Yes, review this video - be very patient and with lots of flux to remove the connector and to apply a fresh one. The fresh one should be soldered with a point to point soldering as we have seen the plastic housing of such connectors warp with the hot air guns. They deform like a Chucky Doll with the hot air tools.

For this reason, remove with hot but replace with normal soldering tools.

Do you have a known good connector already ?

https://www.youtube.com/watch?v=90OLMQNetow

and another:

https://www.youtube.com/watch?v=XqaZpIDEju8

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

I will source a few new ones. They are quite cheap.

Mon2 I thank you for your kind patience and help so far, you are a real gentleman can I offer you any donation?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

When I say flicker, what I mean is that it looks like backlight is coming on, not like screen flickering.

But don't see image on any of the displays, still don't understand why only one shows just white image and others don't. Very confusing.

@mon2, what pins can we check to verify video is going to connector? Is it data lines?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

real gentleman can I offer you any donation?

Please convince my wife of the same...

Donation - at your discretion to this forum. We are all volunteers here and very much in learning phase.

What is the history of the non-working displays ? Were they purchased used from Ebay or similar ? Have they been man-handled already ?

Have had my fair share of lemons from Ebay but also many bargains. I know that we have abused the LVDS connector with the many pulls / insertions so perhaps it is worn out.

Do I understand correctly that you have one working LCD display that has backlight & graphics display ?

Do you have other working A1286 boards at your place ? (for testing)

My further steps would be to remove all power and check the continuity (resistance mode) from the connector pin to the next point that can be probed on the logic board. Each LVDS connection is a suspect till proven otherwise. For LVDS - each and every data line and the differential clock lanes MUST be working.

PS: In my 'spare time', working on a small and affordable jig to test these displays that are MIPI / LVDS style. Not an easy project and learning about FPGA design - something I should have learned in university days but technology has advanced a great deal. Fairly confident that we will be able to test target displays like the A1286 so do not have a problem to buy a few for testing.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

I have some non-working boards on the way but no working ones

What is the history of the non-working displays ? Were they purchased used from Ebay or similar ? Have they been man-handled already ?

Yes all sourced from eBay either as parts or with other defective MacBooks!

Do I understand correctly that you have one working LCD display that has backlight & graphics display ?

One display initially showed graphics and backlight on this board, then during usage suddenly went black and since then has only showed white screen with backlight at best, initially just showed nothing until I cleaned U9600.

So in total I have four displays which I have seen working on other boards that I no longer have - albeit only for short periods of testing. I cannot believe they are all faulty!

Still, I have new LVDS cable coming to eliminate cable as being the issue, can connect this to three of the displays as they are now removed from the housings.

I also got new display connectors arriving!

And some more displays I can test with from some other broken MacBooks.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Mon2,

I see this video from dosdude with almost exactly the same problem but on 13". Is from same year.

Are you able to help me "translate" the steps here to 15" 820-3330B board?