820-00165 green light, no fan spin

[kevinklinkmuller]

have another 820-00165 with green light and no fan spin this time. no sign of liquid damage. initially PRAM reset worked but then it died again. already checked around ISL and pins 17/18 etc. and have normal values (low resistance)

 

[2informaticos]

Post basic voltages and signals...

 

[kevinklinkmuller]

PP3v42 = 3.4
PPVRTC 3.3
PP5V_S5 5v
PP3V3_S5 3.3
PP3V3_SUS 3.3

 

[kevinklinkmuller]

not sure if I should go further down the list?

 

[kevinklinkmuller]

U7100 pin 27/28 20 ohms
Pin 17/18 3.6 ohms

 

[2informaticos]

Poste exact voltage for PPBUS_G3H.
Check if any of PM_SLP_Sx_L signals pulses when trigger SMC_ONOFF_L.

 

[kevinklinkmuller]

PPbus G3h is 8.58

When you say trigger SMC, how do i do that? or is that just plugging it in?

 

[kevinklinkmuller]

none of the PM_SLP_ are pulsing hmm

 

[2informaticos]

Use R5115/16 pads for that.
I prefer to solder a tiny wire on SMC_ONOFF_L and simulate power button touching some metal plate from chassis...
PM_PWRBTN_L must react then. PM_RSMRST_L should be high, of course.
Check if PCH receives 32KHz oscillation.

 

[kevinklinkmuller]

Hmm i think SMC on/off is doing nothing. am not getting anything on PM_PWRBTN_L on PM_RSMRST_L it's always 3.3

How would I check PCH for oscillation? im a noob! haha

 

[kevinklinkmuller]

No Title

coincidentally c7870 has a tiny pit of corrosion/burning on it. probably not the issue though since that line has 3.3v

 

[2informaticos]

PM_PWRBTN_L stays always at 3V?
You should catch a drop pulse when simulate power button.

 

[kevinklinkmuller]

Must've been a bad connection because PM_PWRBTN_L works now. 3.4v normal and then 0.36v when simulating power press

 

[kevinklinkmuller]

So that's working as expected?

 

[2informaticos]

Yes, check now if PM_SLP_S5/4/3_L react too.
Use o-scope, or repeatedly trigger SMC_ONOFF_L if use DC multimeter only.

 

[kevinklinkmuller]

Ok so the S4 sometimes i catch the multimeter going up to 0.025v when triggering just for a second s3 does nothing it appears I think. and neither does s5. something interesting I found accidentally. when triggering power press once, I was accidentally measuring S5_pwrgd and it was pulsing from 0v to 3.3 v constantly until it was eventually stable at 3v. not sure if relevant

 

[2informaticos]

S5_PWRGD should be high before board starts; depends by 3V3_S5.
SMC generates PM_DSW_PWRGD in base of it.
The sleep reactions should be ordered as S5 -> S4 -> S3.
If PM_PWRBTN_L reacts, no sleep reaction will point to PCH.
But you must be sure if no reaction at all.
Catch a cheap analog second hand o-scope; it is good enough for this job.
I don't recommend mini DSO bullshits...
You must also assure PCH gets all necessary signals to power on.

 

[kevinklinkmuller]

Which is the PCH? I can see many different ones on the schematic? Do you think it's fixable with Osciliscope and patience?

 

[kevinklinkmuller]

came accross this vid of rossmann with what looks like the exact same issue https://www.youtube.com/watch?v=uvRaC3VUYR0&list=PLkVbIsAWN2lsjujIe9sbzDDXwQJHShVGI

 

[kevinklinkmuller]

so i basically tested for continuity on SPI_CS0_L and it's ok