MBP Mid-2012 Missing Question-Mark Folder

[Mechanicalbytes]

The MB chimes and has a working screen which illuminates as normal.
I've followed the guides on SMC / PRAM resetting.
I've removed the HHD and reset everything again, still no luck.
I've tried to re-install Mac OS using a USB stick, again no joy.
Nothing seems to recognised when using usb, although they do flash when plugged in.

What should I try/do next.
Any help is greatly appreciated.

[piernov]

Re: MBP Mid-2012 Missing Question-Mark Folder

Boot into Internet Recovery, erase the drive with Disk Utility and reinstall macOS.

[Mechanicalbytes]

Re: MBP Mid-2012 Missing Question-Mark Folder

Followed your instructons, initially I had no joy, although the screen did dim momenterally after a few seconds but nothing happed.
So I tried again with a second display connected through the displayport and hey presto I got an image, the MB screen is still white.
I turned the MB off insterted a HDD with Lion already installed and checked specs, sys info etc.
1. When opening window about this mac it only states it's a Macbook Pro nothing about size or screen. I've included an image(1).
2. Changing the resolution worked fine but the display tab on about this mac states it's a 17 inch. I've included an image(2).

My MBP is a 13-Inch Mid 2012 Core-i5-3210M.

Thanks again.

[piernov]

Re: MBP Mid-2012 Missing Question-Mark Folder

I interpreted your issue as operating system not found. You mentioned the screen to be working, not showing a solid white background.
If there is an issue related to LCD, first thing would be to try a known good LCD.

[luckydip]

Re: MBP Mid-2012 Missing Question-Mark Folder

Did you check the lcd connector on the board and the lcd cable? When you say working screen is it a known working screen or are you going by the fact it illuminates? If its the latter then try a known working screen.

[Mechanicalbytes]

Re: MBP Mid-2012 Missing Question-Mark Folder

I've disconected the screen and connected to a MBP mid-2011 where it works fine, I can see the OS on screen.
So atleast we know the screen is fine.
The LVDS connector looks fine on the MBP, but I've included an image.

I guess it's a case of fault finding along the gpu to screen output? or am going in a totally wrong direction.

Thanks again for the help.

[piernov]

Re: MBP Mid-2012 Missing Question-Mark Folder

It's a 13" so GPU is indide CPU. Check voltage on pins 2/3 of J9000 and all pins of U9000

[luckydip]

Re: MBP Mid-2012 Missing Question-Mark Folder

Can you check diode mode on all 6 LVDS lines (pins 8-18) and voltage on pin 3 on J9000 (lcd connector) ?Is the board number 820-3115?

[Mechanicalbytes]

Re: MBP Mid-2012 Missing Question-Mark Folder

J9000:
Pin 1 0.26v
Pin 2 0.26v

U9000:
Pin 1 3.3v
Pin 2 0.24v
Pin 3 0.24v
Pin 4 0.26v
Pin 5 0.26v
Pin 6 Gnd

6 LVDS lines gave no shorts, with the following readings:
8 1768 ohms
9 1982 ohms

11 1758 ohms
12 1963 ohms

14 1746 ohms
15 1994 ohms

17 1839 ohms
18 1903 ohms

The board is 820-3115-B.
Thanks again for all the help.

[luckydip]

Re: MBP Mid-2012 Missing Question-Mark Folder

voltage on pin 3 on J9000

[piernov]

Re: MBP Mid-2012 Missing Question-Mark Folder

U9000 pins 2/3 should have 3.3V, they are connected to PP3V3_S5 which must be present if the machine turns on. There is probably a break in the line.

[Mechanicalbytes]

Re: MBP Mid-2012 Missing Question-Mark Folder

J9000

pin2 0.26v
pin3 0.26v


Miss labelled the pins sorry

[Mechanicalbytes]

Re: MBP Mid-2012 Missing Question-Mark Folder

If I solder two small wires from Pin1 of C9009 to pins 2/3 on the U9000, this would fix the issue?

[luckydip]

Re: MBP Mid-2012 Missing Question-Mark Folder

If I solder two small wires from Pin1 of C9009 to pins 2/3 on the U9000, this would fix the issue?

If there is voltage on c9009 pin 1 then yes otherwise you'll need to go further back

[Mechanicalbytes]

Re: MBP Mid-2012 Missing Question-Mark Folder

Thankyou Piernov and Luckdip for all the help.

Soldered the wires as mention earlier and this solved the problem. My question mark folder has now been found.