doesn't turn on a1278 3115b

syslan

Member
hi i have the situation very similar to the rossman wiki.

Green light, no light: 0.05 A on power supply.

P5VS3_EN_L = 3.42V (pin 2 of Q7221)
P5VS3_ENTRIP = 0V (pin 6 of Q7221)
When Q7221 was removed, PP5V_S3 was good (5V).

PM_SLP_S4_L = 0 V (pin 1 of Q7911)

in my case the consumption is much lower and the PCH does not heat.

any ideas?
 

2informaticos

Administrator
Staff member
We need more specific information.
3V3_S5/SUS both present?
Exact PPBUS_G3H voltage (without battery)?
Check PCH's RTC signals.

Any history fault available?
 

syslan

Member
I don't have any history of why the computer stopped working.

3V3_S5 = 3.3V
3v3_sus is not present (0V)
Exact PPBUS_G3H voltage (without battery) = 12.56V
 

syslan

Member
SYSCLK_CLK32K_RTC = 0.6V
RTC_RESET_L = 3.3V
PCH_SRTCRST_L=3.3V
PCH_INTRUDER_L=2.11V
PCH_INTVMEN_L=2.70V


PM_BATLOW_L = 0V
PM_DSW_PWRGD = 0V
PCH_DSWVRMEN =1.95V
 

syslan

Member
I soldered U7941 again and now I have the 3 signals


PM_BATLOW_L = 3.2V
PM_DSW_PWRGD = 3.44V
PCH_DSWVRMEN = 2.5V

and also S5_PWRGD = 3.05V
 

2informaticos

Administrator
Staff member
PCH_INTRUDER_L is a bit too low; just too close at lower limit (2.1V).
Force it soldering 330K instead of 1M, at R1801.
 

syslan

Member
Measuring PCH_INTRUDER_L I see that it is a bit unstable. starts at 1.70V and goes up until it reaches 2.10V, 2.12V approximately
 

2informaticos

Administrator
Staff member
Very important.
Possibly accumulated crap underneath PCH, or PCH sinks too much current on that line.
Force the signal, as above explained.
 

piernov

Moderator
Staff member
Make sure you don't touch the probes when measuring and you use a decent multimeter (10MΩ input impedance), since INTRUDER# has a very weak pull-up of 1MΩ is it pulled down very easily.
 
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