820-2132-A, A1229 blinking light on magsafe

[lcdcaps1]

Hi
All
I have an old Macbook pro, A1229 (820-2132-A)
I can't remember why this stopped working before and what i did to troubleshoot it before
It's been many years but today I wanted to look at it again

I checked over the board and can't see any burnt marks or anything looking out of place

I started troubleshooting the voltage rails but when I plug in My Magsafe (Original, 85w charger) and I use My tweezers to short the power on pads to turn on, the magsafe charger starts blinking

I don't know if this is a problem with the left I/O board or the logic board
I don't have a spare Left I/O board and don't really want to burn cash to getting one, instead would really like to repair the Left I/O Board.

Can anyone help me please to diagnose this
I can't see anything wrong visually with the Left I/O board


I will really appreciate it very much

Many Thanks
Kind Regards

[piernov]

Re: 820-2132-A, A1229 blinking light on magsafe

Go through the list of power rails and measure voltage when off, voltage after pressing power button and resistance to ground.

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

Go through the list of power rails and measure voltage when off, voltage after pressing power button and resistance to ground.

Hi
Thanks for the reply
I was about to do that but I just want to rule out if it is a bad IO board
I don't have a spare one
How can i do that
anyone had any experience with these please

[piernov]

Re: 820-2132-A, A1229 blinking light on magsafe

You can't trivially rule it out. It's a pretty complex one on this machine. It contains the discrete circuit for 1-wire protection and its own 3V/5V regulator for audio and USB circuits (on the LIO board as well), and they could be part of the problem as well.

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

You can't trivially rule it out. It's a pretty complex one on this machine. It contains the discrete circuit for 1-wire protection and its own 3V/5V regulator for audio and USB circuits (on the LIO board as well), and they could be part of the problem as well.

Hi
Yes I saw that
I saw a video online where a macbook DC in board was repaired, although it was newer than this one
But I saw another one where the DC voltage was leaking onto to the data line

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

Hi i have an update
I have a green light on the charger and I have been following the voltages
I have checked so far
PP18V5_G3H_CHGR
I have voltage on CHGR_EN
I have voltage on PPDCIN_G3H
I have PP3V42_G3H

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

I have gone through all the power rails and below are voltages
PP18V5_DCIN 16.42v
PP18V5_G3H_CHGR 16.42v
U7900, CHGR_EN 4.8V
PPDCIN_G3H 15.41v
U7800, VIN 15.22v
U7800, SHDN 15.22v
PP3V42_G3H 3.4v
PPBUS_G3H 12.59v
PPDCIN_G3H 15.41v
PP3V42_G3H 3.4v
PP5V_S5 0v
PP5V_S3 0v
PP5V_S0 0v
PPVCORE_S0_CPU 0v
PPVCORE_S0_NB_GFX 0v
PP3V3_S5 3.2v
PP3V3_S3 0v
PP3V3_S0 0v
PP1V25_ENET_ISNS 0v
PP1V8_S3 0v
PP1V8_S3_ISNS 0v
PP1V8_S0 0v
PP1V5_S0 0v
PP1V25_S0 0v
PP1V05_S0 1v
PPVCORE_S0_NB_R 1v
PP0V9_S3_MEM_VREF 0.9v
PP0V9_S0 0.9v
PP3V3_ENET 3.2v
PP1V9_ENET 0v
PP1V25_ENET 0v
PPBUS_FW_FWPWRSW_F 12.59v
PPVP_FW 12.41v
PPVP_FW_PORTA_UF 12.42v
PPVP_FW_PORTB_UF 12.39v
PP3V3_FW 3.3v
PP1V95_FW 1.9v
PP3V3_GPU 0v
PP3V3_GPU_TMDS 0v
PP1V8_GPU 0v
PP1V25_GPU 0v
PPVCORE_GPU 0v

[piernov]

Re: 820-2132-A, A1229 blinking light on magsafe

PP5V_S5 0v

That would be a problem, double check this measurement.

PP1V05_S0 1v
PPVCORE_S0_NB_R 1v
PP0V9_S3_MEM_VREF 0.9v
PP0V9_S0 0.9v

It sounds suprising that some random S0 rails come up when you're not even getting correct PP5V_S5, and no other S3 rails. Again double check your measurements.

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

That would be a problem, double check this measurement.


It sounds suprising that some random S0 rails come up when you're not even getting correct PP5V_S5, and no other S3 rails. Again double check your measurements.

So I need to find out what creates PP5V_S0

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

Does anyone know what can be used as a substitute for IRF7707PBF, please

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

Hi
This machine model does not auto power on when magsafe is connected
I plugged in magsafe and touched the power on pads with tweezers to turn on and get voltage measurements
I get a green light and voltage measurements are as I posted them

I get 5v on pin 1 on u7300, which is PP5V_S5
but if i check other places where PP5V_S5 should be is not there

Can anyone advise on what might cause this
has anyone got experience with this board, please
Thanks

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

I have 4.9v on PP5V_S5
I checked on c8900

[dellxps15]

Re: 820-2132-A, A1229 blinking light on magsafe

in diode mode value of gpu power rail ? it has old nvidia kown to fail...

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

in diode mode value of gpu power rail ? it has old nvidia kown to fail...

Hi seems like it is trying to boot because The fan starts to spin and then stops
About 2 seconds between starting and stopping
I checked all_sys_pwrgd, on Pin 4 of u7880 and get 3.2v

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

in diode mode value of gpu power rail ? it has old nvidia kown to fail...

Which power rail for the gpu
there are a few

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

ok on c1252 which is PPVCORE_S0_CPU i get 0,7v

If I keep My probe on c1252 and when the fan starts I get 0.7v but then when fan stops the voltage goes down to 0v but when fan starts spinning the voltage goes to 0.7v

[piernov]

Re: 820-2132-A, A1229 blinking light on magsafe

Of course the GPU will be dead if it hasn't been replaced by the fixed revision, but they don't short when failing. Only when they are mistakenly reflowed…

[dellxps15]

Re: 820-2132-A, A1229 blinking light on magsafe

half fan spin could be also cpu circuit... clock generator and so on

[lcdcaps1]

Re: 820-2132-A, A1229 blinking light on magsafe

half fan spin could be also cpu circuit... clock generator and so on

any chance of helping me further, please
I know that this model had a bad gpu but surely the fan should spin continuously

[dellxps15]

Re: 820-2132-A, A1229 blinking light on magsafe

if it was a newer model we could see if current resistor were ok, but here it use ISL6255AHRZ and different layout. tomorrow ill see datasheet and see if we can find some news

edit: check if R7905 is 18 ohm