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820-3476 U2800 U3900 and PCH heating up

No-Clean

No-Clean

Member
Board had small corrosion on a couple caps and keyboard connector, got all that cleaned and fixed, but still same behaivior.

U2800 U3900 and PCH are heating up while the board tries to startup.

smc bypass doesn't seem to do anything

Board sits around 70-80ma

ppbus 12.6v
smc_reset_l 3.3v
smc_onoff_l 3.4v
 
2informaticos

2informaticos

Administrator
Staff member
If the board only tries to start, no way to heats the chips so fast.
Unless it takes some time "trying to start".
What about 3V3_S5/SUS and RTC voltage?
Any S3/0 voltage tries to appear?
 
No-Clean

No-Clean

Member
It takes a few seconds for the chips to heat up.

pp3v3_s5 3.3v
pp3v3_sus 3.3v
ppvrtc_g3h 3.3v
rtc_reset_l 3.3v

pp3v3_s3 3.3v
PP1V05_S0_REG_R 1.05v
 
2informaticos

2informaticos

Administrator
Staff member
So you also get S0 voltages.
Post all the volatges you have and specify if go off in time, or stable.
 
No-Clean

No-Clean

Member
This board now has a new SMC and clean BIOS, with those 2 things the behavior is the exact same.

At 12 seconds they all go off then come back and stay steady after that with their respective voltage.

Board stays around ~0.065a steady after a few seconds.

PP5V_S0
PP3V3_S0
PP5V_S0_FET
PP3V3_S0_FET
PP3V3_S0SW_SSD
PP0V675_S0_DDRVTT
PP1V05_SUS
PP1V5_S0
PP1V05_S0SW_PCH_HSIO
PPVCC_S0_CPU
 
2informaticos

2informaticos

Administrator
Staff member
Looks like PCH issue; heat it with quality flux.
May have luck and could be only crap accumulated underneath...
 
No-Clean

No-Clean

Member
OK so in this board the PCH is integrated on the CPU, should I use the zaomao for this?

If not just put good flux and heat with how air?
 
2informaticos

2informaticos

Administrator
Staff member
NO, you don't need to melt the balls.
180-200 degrees is more than enough to burn eventual crap.
Use only hot air station...
 
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