A2141 820-01700 no power

[hgoncalves]

Hi.

I have an A2141 820-01700, that seams to try to boot but then powers off. It puls 20V from ampmeter, reaches 0.400A, but then drops to 0.100A.

DFU goes until the end, and a lock appear on the host mac, but nothing appends on the dead mac.

No big coils have voltages, but none seams to be shorted on diode readings.

PP3V3_S5 = 3.3V
PP1V8_S5 = 1.8V

PMU_CLK32K_PCH = 0.869V
PMU_ACTIVE_READY = 1.8V
PMU_ONOF_L = 3.3V


PP1V8_SLPS2R = 1.8V
PP1V1_SLPS2R = 1.1V
PP0V8_SLPS2R = 0.8V

PP1V8_AWAKE = 1.8V
PP3V3_AWAKE = 3.3V
PPVDDCPUSRAM_AWAKE = 0.8V
PP1V2_AWAKE = 1.2V

Can you help?

 

[2informaticos]

"DFU goes until the end, and a lock appear on the host mac, but nothing appends on the dead mac"
Revive, or restore?

Do you get SSD voltages?
Also check G3S ones.

 

[hgoncalves]

Hi,

Sorry, I meant DFU restore.

PP1V8_G3S = 1.8V
PP5V_G3S = 5.1V

PP0V9_SSD1 = 0.899V
PP1V8_SSD1 = 1.8V
PP2V5_NAND_SSD1 = 2.5V

PP0V9_SSD0 = 0.9V
PP1V8_SSD0 = 1.8V
PP2V5_NAND_SSD0 = 2.5V

 

[2informaticos]

Check diode mode to ground on all big coils; compare with good board.
Any of them gets voltage?

 

[hgoncalves]

Only L7660, L7600 and L7030 have voltages:

L7660 = 3.3V
L7600 = 5.1V
L7030 = 10.73V

I don't have other board to compare diode redings, but it seams that no big coil is shorted. Maybe L3500 is a bit low, not sure...

L7600 = 0.401
L7660 = 0.376
LA950 = 0.037
LA870 = 0.045
LA860 = 0.045
LA750 = 0.008
LA850 = 0.057
L7231 = 0.006
L7330 = 0.040
L7221 = 0.006
L7211 = 0.006
L7420 = 0.012
L7410 = 0.012
L8102 = 0.120
L7701 = 0.153
L7030 = 0.479
L8410 = 0.827
L3500 = 0.227
LB700 = 0.196

 

[2informaticos]

Compare diode mode readings on LA750 with good board.

 

[hgoncalves]

Hi.

Compared with a known good board with a mac broken display, I get the same values:

LA750 = 0.007

However, L7330 has 0.,and on the good board it has 0.040. That´s the major diference comparision

 

[2informaticos]

"L7330 = 0.040"
Is your previous reading...

 

[hgoncalves]

Sorry. It was a typo.

I meant on the known good board, L7330 = 0.025, and on the bad board L7330 = 0.040

 

[2informaticos]

"reaches 0.400A"
Check for pulse on big coils, at same time.

 

[hgoncalves]

No pulse on any big coil, except L7030 that goes until 14V and then stabilizes at 11.30V

 

[2informaticos]

Test if board turns on alone on the desk.

 

[hgoncalves]

No it doesn't. I'm already testing it alone on the desk

 

[2informaticos]

Trigger PMU_ONOFF_L and check for drop pulse at PM_PWRBTN_L, at same time.

 

[hgoncalves]

When trigering PMU_ONOFF_L, I don't have a drop pulse at PM_PWRBTN_L.

It stays stable at 3.3V

 

[hgoncalves]

When trigering PMU_ONOFF_L, I don't have a drop pulse at PM_PWRBTN_L.

Do you think it is PCH?

 

[2informaticos]

This signal is controlled by T2; however PCH may block it.