Macbook A2337 820-02899 Stuck at 5V

[Instafixx]

PPBUS 12.3V
PP3v8_AON is 3.8V

S2 Rails Missing 5V/3v3/1v25 - No Shorts

P5VS2_EN is at 1.5V
PP3v3_s2_upc is 0V
P3v3_UPC_LDO is 3.3V


Using the 820-02016 boardview as basis

 

[2informaticos]

Any history available?
All MPMU/SPMU LDOs OK?

 

[Instafixx]

No history available.

PP1v25_s2 0V
PPVDD_PMU_LDO_PREREG is 0V
PP1V06_S2SW_DRAM is 0V
PP0V88_S1 is 0V
PP3V8_AON_VDDMAIN is 3.8V

 

[2informaticos]

U8100 & U7700 have more LDOs.
Check diode mode on the ones with missing voltage; compare with good board.

 

[Instafixx]

PPVDD_PCPU_AWAKE is 0.032 diode reading. It should be 0.06 as per openboard.

 

[2informaticos]

I saw several wrong readings on that page.
May be the case now.

BTW, you may have problems getting lower reading on a power rail, instead of expected.
However mentioned rail is not a LDO; it should come on later.

 

[Instafixx]

i saw some flux paste around U8100 - maybe previously some work done . I removed and reballed both U7700 and U8100. Device turns on now.

 

[Instafixx]

It turns on but no TP/KB. No Capslock toggle. No Display.
I get external video.
I put in another board on this chasis to verify all are okay. Issue is with the MLB.

The sensor behaviour was same in both MLBs ruling out UR200 issues.

Tried DFU Revive. Gave error -1.
No i get the chime but no external video.
PPBUS at 12V.

Trackpad connector no shorts.

 

[Instafixx]

Checking only board and trackpad connected

LT400 is 12V
LT401 is 3.3V Both Pins
LT402 is 0V on both Pins
LT403 is 5V on both Pins

Have replaced UT310/30/60 Just in case. Still the same.
LT402 is 0V

 

[2informaticos]

Check UC830 voltages.

 

[Instafixx]

1 - p3v3_s2sw_ipd_dvdt - 0.145v
2 - p3v3_s2sw_ipd_en - 1.47 v
3/4 - pp3v3_s2 - 0.780 v
5 - pp3v3_s2sw_ipd - 0 v
6 - p3v3_s2sw_ipd_flt_l - 1.7 v
7 -p3v3_s2sw_ipd_ilm - 0v
8 - gnd

 

[2informaticos]

Fix 3V3_S2 problem; check UC710.

 

[Instafixx]

1 - ppbus_3v3s2_vin - 2.7 - 2.8 v
2 - p3v3s2_sw - 0.798 v
3 - gnd
4,10,11 - p3v3s2_agnd - 0v
5 - p3v3s2_fb - 0.197
6 - p3v3s2_vos - 800
7 - p3v3s2_pgood - 0v
8 - p3v3s2_en - 1.8 v
9 - p3v3s2_ss - 0v

I replaced UC710. Its still the same.

Input should be 12V but somehow its 2.8V.
No shorts on any other rails as well.

Can it be U8100? Since we reballed this one to get the machine back to work- is it possible that the chip is partially damaged.
I replaced the U8100. Still the same.

 

[Instafixx]

Please help.

 

[2informaticos]

Check RD560 and its traces.

 

[Instafixx]

I had replaced RD560 but didnt work. Replaced again with a jumper from PPBUS to PPVIN. Machine turns on now.

 

[2informaticos]

"Check RD560 and its traces"
Broken trace....

If you bypassed RD560, M1 CPU can't supervise 3V3_S2 current consumption.