A1398 820-00163/00426 No fan spin PPBUS_G3H ok PP5V_S5 ok but not S4, PP3V_S5 ok but not S4, no PP3V3_SUS

[stef4n]

Good evening,

I started investigations on a board that suddenly stopped working out of the blue. I get an Amber Light, fan spinning, PP5V_S5, PP3V_S5, but no S4. I do not have any PP3V3_SUS.
Logic board is out of the case.

PPBUS_G3H: 12.53V
PP5V_S5: 5.00V
PP5V_S4: 0V
PPVRTC_G3H: 3.24V
PP3V3_S5: 3.306V
PP3V3_S4: 0V

U7501:
PP5V_S4 (pin2) : 0V
P3V3S5_RF (pin3) : 1.246V
P5VS4_EN (pin4) : 0V
SMC_PM_G2_EN (pin12) : 3.402V
P3V3S5_EN (pin21) : 3.402V
VIN (pin23) : 12.52V
pin 29: 5.00V

U8170
PP3V3 S5 (pin6) : 3.3V
SMC_S4_WAKESRC_EN (pin1) : 0V
PM_SLP_S5_L (pin2) : 0V
S4_PWR_EN (pin4) : 0V

Page 66, 3.3V SUS FET:
PP3V3_S5 (Q8020 pin6 + R8022pin1) : 3.305V
P3V3SUS_SS (Q8020 pin3 + test probe) : 3.27V
PP3V3_SUS (Q8020 pin2 + test probe) : 0V
P3V3SUS_EN_L (R8022pin2): 3.275V
PM_SLP_SUS_L : 0V

As I found this post: https://boards.rossmanngroup.com/threads/a1398-820-00163-no-pp5v_s4.61990/
Which seemed a bit similar but might not be at all, here are more voltages:
SMC_ADAPTER_EN : 3.375V
PM_BATLOW_L : 3.3V
PCH_DSW_PWRGD : not found
PCH_DSWVRMEN : 1.173V
PM_RSMRST_L : 0V
PM_PWRBTN_L : 3.4V
SMC_ONOFF_L : 0V

Currently on pages 66/67 of the schematics; U8170 gets the PP3V3_S5, and should enable S4_PWR_EN, provided that PM_SLP_S5_L and SMC_S4_WAKESRC_EN have the expected values.

What exactly is missing is still unclear.

About Q8020; it is a P-Type, which gets 3.3V on the source, and less than that on the Gate, as P3V3SUS_SS is 3.27V. I should get 3.3 on the Drain, shouldn't I ? Or the difference is not significant? Then voltage on the gate should be much lower. And PM_SLP_SUS_L actual value is problematic

 

[2informaticos]

PM_SLP_SUS_L is controlled by PCH.
So check its RTC (DC) signals, at page 11.
Also check SMC_ADAPTER_EN, PCH_DSWVRMEN, PMDSW_PWRGD, PM_BATLOW_L.

 

[stef4n]

Good Evening 2informaticos,

SYSCLK_CLK32K_RTC : 233mV
PCH_SRTCRST_L : 1.21V
PCH_INTRUDER_L (R1101, pin2) : 1.104V
PCH_INTVRMEN_L (test probe & R1100, pin2) : 1.174V
RTC_RESET_L : 1.21V

(PPVOUT_S0_PCH_DCPRTC : 2.4mV)
(PPVRTC_G3H : 1.215V)

Regarding the other measures, as per yesterday for 3 of them, just adding DSW_PWRGD

SMC_ADAPTER_EN : 3.375V
PCH_DSWVRMEN : 1.173V
PM_BATLOW_L : 3.3V
PM_DSW_PWRGD: 2.056 V

(Note: no o-scope available for the time being)

 

[2informaticos]

"PPVRTC_G3H : 1.215V"
That is the problem.

Try replacing U1900.
Be sure no caps corroded on the mentioned rail.

 

[stef4n]

Thanks 2informaticos; I will check C1924, C1920, C1922, C1902, C1905, C1906, C1910, C1102, C1103 tomorrow evening and update this reply once done.
Will see if I can find a donor board by then, for U1900 replacement. Otherwise, I will order a bunch of U1900. In all cases I will update this post tomorrow evening. I'm sorry I couldnt do it today, the day was too short.

 

[stef4n]

All caps looked good.
I replaced U1900 with a chip from a donor board.
I have 1.26V for PPVRTC_G3H. Still far from 3.3V

SYSCLK_CLK32K_RTC now shows 35mV (233mV before)
PCH_DSWVRMEN : 1.217V
PM_DSW_PWRGD: 2.094 V

I blew C1740 a few times. I put it back in place. Is there a polarity on this one?
(Still possible that the donor board suffered from the same issue)

 

[2informaticos]

C1740 is unpolarized ceramic capacitor.

If U1900 and all corresponding caps are good, then bad PCH.
Just in case, check voltage at pins 2, 5 & 13 of U1900.

 

[stef4n]

pin 4: 314mV
Other pins values are disturbing. I checked after having resoldered, I had the PP3V3_S5 yesterday.
I plugged the powercable a few min ago but this morning I have nothing.
pin2 & pin5 "peak" for a fraction of a second at 3.x V when I touch the pin with the multimeter probes prior to immediately going down to 0V. If I measure other points on the logic board (same rail, 3 other points), i get zero volt on each too.
Pin 13 shows 0V. Either I did a poor job when replacing this IC, or the one from the donor board was dead.

Will redo my job this evening and update this post.
Thanks for the support so far

 

[stef4n]

The battery of my multimeter was dead...I have the correct voltage on pins 2, 5, and 13 of U1900. Nice and steady 3.3V, 3.42V.
Visually all the caps look good. How do you proceed in such a case ? Take each cap out of the board and test them ? Or replace all of them ?
There is no sign of corrosion on this board.

 

[2informaticos]

Take them out one by one.
No need immediat replacement.
Need to confirm first if isn't PCH problem.