Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

[Pgratis]

Hi,

I have one MBP 13" that started to refuse to boot.

Two months ago the WiFi chip stopped working but that was solved by putting a Wifi USB dongle (the Aliexpress Wifi Module is on it's way since early April).

This weekend the MBP didn't started. When pressing the power button I saw some activity (the led was on and I got the DVD head sound, but black screen and no chime).

After some time I've replaced the current DIMM's (1 original 2GB PC3-8500 + 1 PC3 10600) that have worked without issues since 2012, with new DIMM's.

Then the weird stuff started to happen.
When using only PC3-8500 DIMM's (from another Mac that is working great) there is no boot.
When using only new PC3-10600 DIMM the MBP boots, I get the white screen with the Apple logo and the progress bar goes up to 60% and then it starts to loop reboot.

I've opened the MBP, made visual inspection and the only thing I see is there are some dry solder joints on 2 inductors (L7400 and L7401) that power the CPU, but I guess it's not related to this problem.

My wild guess is there must be some capacitor which is malfunctioning and driving the DIMM voltage to a level that the PC3-8500 don't “like”, but I cannot find where to look for.

Any suggestion is more than welcome.

Thanks.

BR,
PMA

[piernov]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

You MUST use PC3-8500 on this machine. Not sure why it wouldn't work with it though, clean the RAM slots and try another RAM stick. (try each slot alternatively, the one closest to keyboard can fail)
Note that the cheap RAM sticks coming from China are often misadvertised with wrong frequency, don't trust them…

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Hi,

I know I need PC3-8500 for it to work (I've been using one original DIMM to trick the chipset to lower the frequency for quite a few years now).

I've tried 3 different PC3-8500 modules from a working Mac but this motherboard refuses to boot with all of them.

I've reset the SMC (with keyboard and by removing the battery) to see if the chipset would start to collaborate, but this MBP now only "likes" PC3-10600 DIMM's.

I'm adding some photos of the motherboard.

Thanks for the prompt reply.

BR,
PMA

P.S. - The DIMM's are only from reputable sources (Micron/Samsung)

[piernov]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Inductors look ok.
Did you try PRAM reset as well?
Motherboard is pretty dusty so always good to clean that. Note that if you are in a high humidity environment, dust can catch the humidity and disturb signal lines. Remove the speaker as well.
Dust can also get into the RAM slot and cause weird problems.

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Inductors look ok.
Did you try PRAM reset as well?
Motherboard is pretty dusty so always good to clean that. Note that if you are in a high humidity environment, dust can catch the humidity and disturb signal lines. Remove the speaker as well.
Dust can also get into the RAM slot and cause weird problems.

I can't reset PRAM with the "official" DIMM's because I never get the white boot screen, but I've done it several times with the higher speed DIMM's, so I believe that part is don.

I've cleaned the board out of dust but I'm having doubts how to clean the RAM slot contacts.

Thanks.

BR,
PMA

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Hi,

I've cleaned the board, replace the thermal grease and remounted the system but still the same behaviour.

I've tried to use the original DIMM on both slots but there is no boot.

With the 1333MHz DIMM's the boot goes up to 50-60% and then starts looping.

Any ideas?

Thanks.

BR,
PMA

[SMDFlea]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

What voltage do you get on PPSPD_S0_MEM_A

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

On the board view that would be "PP3V3_S0", right?

I've measured 3.25VDC on a resistor that was connected to that line.

I've also measured the DIMM VDD "PP1V5R1V35_S3" and it measures 1.48VDC.

BR,
PMA

[piernov]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

The behaviour with non-PC3-8500 RAM is expected. I genuinely have no idea what's causing the issue with PC3-8500, maybe a dying MCP but still weird that it POSTs with non-PC3-8500.

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Hi,

I've tried several techniques to identify what is happening with this logic board but I'm on a dead end.

With the correct DDR3 modules:
- I've measured the power buses and all seems to be ok.
- I've heated up the logic board (using a hot air gun) to see if some capacitor would start working, but no fun either.

The computer keeps POST works ok with the higher speed DDR3 modules.

Any ideas?

Thanks.

BR,
PMA

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Hi,

I've replaced the DIMM with new 1066MHz version.

I was able to reboot the MBP once and run the ASD EFI without any errors but I have to stopped it because the computing was getting very hot and the fan was spinning in normal speed which could damage the logic board.

Now when I try to start it I see the fan spinning hear the DVD drive seek but get the black screen and no chime.

Taking out the 1066MHZ DIMM and putting the 1333MHz DIMM alone in either slot I can have the logo and the OS starts to load.

Mixing both DIMM's I get the same black screen and no chime.

I have PPVCORE_S0_CPU with 1.1V and PP1V5R1V35 with 1.48V with either DIMM's.

Any help is appreciated.

Thanks.

BR,
PMA

[EDIT] P.S. - I've noticed that, even with the black screen, the MCP and CPU are getting very hot.

[Pgratis]

Re: Macbook Pro 2010 13" A1278 (EMC 2351) boot loop

Hi,

Here follows my update.

After a huge fight with the Logic Board, where I've reflowed the MCP and the CPU with a hot air gun the symptoms kept the same.

One thing I've remembered while in desperation was to correlate this issue with the Wifi board malfunction and Bingo!!!

After disconnecting the Wifi/camera cable from the logic board the MBP booted normally and started working without any major issues.

Then I've unplugged the Wifi board and the MBP kept booting, so it ruled out being a problem on the camera.

I've runned the ASD with success (only complained about the HDD - which I've replaced with a SSD), so no problems.

Now I'm waiting for the replacement wifi board to close this subject.

Actually I will need to downgrade the OS from High Sierra to Sierra. The poor Core 2 Duo is being pushed to the limit with the High Sierra.

Thank you all for your tips and assistance.

Hope my message can also help someone.

BR,
PMA