Greetings uk.comp.sys.mac. Last time I was here was about 10 years ago. I apologised for not having been here for about 10 years. I feel very old!

The point of my post is this: I have an old 2012 Macbook Pro i7 (A 1278). The other day, it gave me the white screen of death. My research took me to this video: https://youtu.be/b3knhnxan9Q?si=1So7F8jjXzGnd0ss
.... which shows the same problem being fixed on an identical Mac.

Examination of my own machine revealed that the problem was caused by the same component failure, and I was wondering if anyone knew what the value of this particular resistor is (just below the LVDS connector).
https://drive.google.com/file/d/1lD2GWzOeE_NrcZyUxsKKogJ_mCic8Ud8/view?usp=sharing

Thanks in advance.
Graham R

On 2023-11-02, Graham Raine <grahamrainemusic@gmail.com> wrote:
> Greetings uk.comp.sys.mac. Last time I was here was about 10 years ago. I apologised for not having been here for about 10 years. I feel very old!
>
> The point of my post is this: I have an old 2012 Macbook Pro i7 (A 1278). The other day, it gave me the white screen of death. My research took me to this video: https://youtu.be/b3knhnxan9Q?si=1So7F8jjXzGnd0ss
> ... which shows the same problem being fixed on an identical Mac.
>
> Examination of my own machine revealed that the problem was caused by the same component failure, and I was wondering if anyone knew what the value of this particular resistor is (just below the LVDS connector).
> https://drive.google.com/file/d/1lD2GWzOeE_NrcZyUxsKKogJ_mCic8Ud8/view?usp=sharing

Welcome back! I don't know the answer but Jon B at Bramley Computers might be
able to help, (although I expect he will offer to do the job for you ;) )

<https://bramley-computers.co.uk>

--
Cheers, Alan

On 04 Nov 2023 at 19:29:39 GMT, "Alan B" <alanrichardbarker@gmail.com.invalid>
wrote:

> On 2023-11-02, Graham Raine <grahamrainemusic@gmail.com> wrote:
>> Greetings uk.comp.sys.mac. Last time I was here was about 10 years ago. I
>> apologised for not having been here for about 10 years. I feel very old!
>>
>> The point of my post is this: I have an old 2012 Macbook Pro i7 (A 1278). The
>> other day, it gave me the white screen of death. My research took me to this
>> video: https://youtu.be/b3knhnxan9Q?si=1So7F8jjXzGnd0ss
>> ... which shows the same problem being fixed on an identical Mac.
>>
>> Examination of my own machine revealed that the problem was caused by the
>> same component failure, and I was wondering if anyone knew what the value of
>> this particular resistor is (just below the LVDS connector).
>> https://drive.google.com/file/d/1lD2GWzOeE_NrcZyUxsKKogJ_mCic8Ud8/view?usp=sharing
>
> Welcome back! I don't know the answer but Jon B at Bramley Computers might be
> able to help, (although I expect he will offer to do the job for you ;) )
>
> <https://bramley-computers.co.uk>

I shall be sending him a 2007 Mini in a few days for some R&R. We use that
Mini to drive our slide scanner, and yesterday after working for a few hours
it refused to wake up, or, after power off/on, to boot (no chime).

--
Tim

Graham Raine <grahamrainemusic@gmail.com> wrote:
> Greetings uk.comp.sys.mac. Last time I was here was about 10 years ago. I apologised for not having been here for about 10 years. I feel very old!
>
> The point of my post is this: I have an old 2012 Macbook Pro i7 (A 1278). The other day, it gave me the white screen of death. My research took me to this video: https://youtu.be/b3knhnxan9Q?si=1So7F8jjXzGnd0ss
> ... which shows the same problem being fixed on an identical Mac.
>
> Examination of my own machine revealed that the problem was caused by the same component failure, and I was wondering if anyone knew what the value of this particular resistor is (just below the LVDS connector).
> https://drive.google.com/file/d/1lD2GWzOeE_NrcZyUxsKKogJ_mCic8Ud8/view?usp=sharing

To do this, we need to download the boardview file for this board, which can
be found here:
https://www.alisaler.com/macbook-pro-13-a1278-820-3115-b-boardview/

Then we need some software to open boardview files - I used OpenBoardview (I
had to build it):
https://github.com/OpenBoardView/OpenBoardView

If I open the boardview file in OpenBoardView and flip to the other side of
the board, I can see the component is L9004:
https://ibb.co/jJLzKyJ

The connector end of L9004 goes to PP3V3_LCDVDD_SW_F and the other end to
PP3V3_LCDVDD_SW.

Since it's an inductor, I would expect a low resistance reading across it.
If you don't get that, it's dead Jim.

Then if we grab the schematic:
https://www.alisaler.com/macbook-pro-a1278-13-i5-820-3115-b-schematic/
and search for L9004, it's marked
FERR-120-OHM-1.5A
0402-LF

That indicates a 120 ohm, 1.5 amp ferrite bead in an 0402 package. All of
these would fit that description:
https://uk.farnell.com/w/c/passive-components/emc-rfi-suppression/ferrites-ferrite-assortments/ferrite-beads?ferrite-bead-case-package=0402-1005-metric-&impedance=120ohm&dc-current-rating=1.5a

although we have no clues as to its frequency response.

That component going open circuit does sound a plausible reason for failing
to display anything - it probably powers up some part of the LCD panel.

However, since this is a power line, I think the idea is for the ferrite to
block conducted RF noise into the display and allow a path for DC power, in
which case probably any of them will do that job to a greater or lesser
extent.

You could also just short it out (since a short would also allow DC power to
pass, and a little extra RF noise won't kill anyone), although perhaps it
popped for some reason other than old age, and it might be safer to replace
it in case whatever that reason is decides to make it pop again.

Theo

Theo wrote:

[snip]
>
> You could also just short it out (since a short would also allow DC power to
> pass, and a little extra RF noise won't kill anyone), although perhaps it
> popped for some reason other than old age, and it might be safer to replace
> it in case whatever that reason is decides to make it pop again.
>

The fqilure, particularly with the track damage on the video, would
suggest a design fault ...

--
Graham J

Many thanks for the helpful feedback guys.

I thought it was a resistor, but if it's an inductor, that would explain the small piece of wire where the component used to be. It may have blown because the Mac was running quite warm at the time, sitting on top of the duvet.

The new Apple Silicon ones look nice and shiney, but I like having an SD card slot and an optical drive and my 1TB SSD. If I can manage to keep this one running by replacing a single component, then I'd like to save the expense and inconvenience.

Graham Raine <grahamrainemusic@gmail.com> wrote:
> Many thanks for the helpful feedback guys.

> I thought it was a resistor, but if it's an inductor, that would explain the small piece of wire where the component used to be. It may have blown because the Mac was running quite warm at the time, sitting on top of the duvet.

> The new Apple Silicon ones look nice and shiney, but I like having an SD card slot and an optical drive and my 1TB SSD. If I can manage to keep this one running by replacing a single component, then I'd like to save the expense and inconvenience.

What do you use in this 2012 MBP these days when it works? Can it run newer than Catalina v10.15 for macOS updates?
--
"But remember the Lord your God, for it is he who gives you the ability to produce wealth, and so confirms his covenant, which he swore to your forefathers, as it is today." --Deuteronomy 8:18. Boo 2 USC, time changes (please keep daylight saving 4eva), my sick body, etc. again. :(
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