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820-2936a missing pp5v_s3

K

Kyle93

Active member
Board had severe liquid damage but since then have replaced all components that had liquid damage.

I now have green light and have all power rails leading up to pp5v_s3 is missing. Already replaced u7200.

PPBUS 12.60V

12.59v on pin 16 U7200

C1802/C1803 are 2.882 V

Also PM_SLP_S4_L is 0v. Does this automatically mean dead pch?


what to check or try next?
 
2informaticos

2informaticos

Administrator
Staff member
Do you get any pulse at PM_SLP_S4_L at least?
Short power pads on the board and see if reacts.

PM_SLP_SUS_L is OK?
 
K

Kyle93

Active member
No Title

Here are some pictures of the board. I will get back to you later on the requested measurements.

also forgot to mention rtc circuit is working as it should to power the pch.
 

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J

JohnB8812

New member
That could be literally anything I prob wouldn't even take something like that in. Upload a picture of the BIOS area currently. Also check resistance to ground on CPU VCore.
 
larossmann

larossmann

Administrator
Staff member
Could be thunderbolt circuit, could be corrosion under SMC, bad BIOS traces, firewire chip... that board is terrible looking.
 
K

Kyle93

Active member
PM_SLP_SUS_L is missing along with SMC_BATLOW_L

I replaced the smc but still no change. traces around smc look good. should I assume bad smc?

bios area looks good
 
K

Kyle93

Active member
Replaced SMC again with a known good smc from a board that had a short inside the board but still no change.

what else to check?
 
2informaticos

2informaticos

Administrator
Staff member
"all 4 RTC signals"
Almost always, people posting only two.
As the other two don't have "RTC" in the name, nobody pay atention.
But schematic clearly show them connected to PCH's RTC block...

Y5010 oscillates?
Do you have 3V3_S5 present?
Check S5_PWRGD and PM_DSW_PWRGD.
PM_BATLOW_L is also low?
 
K

Kyle93

Active member
PCH_INTRUDER_L 2.849v

PCH_INTVRMEN_L 2.201v

Y5010 is not oscillating and is at a steady 1.578V

3V3_S5 0v

S5_PWRGD 0V PM_DSW_PWRGD 0V

PM_BATLOW_L 0.017v

Put board in ultrasonic again earlier since liquid damage was so bad. Before board was drawing 0.20amps and now the board is using 0.142 amps and u7200 is very hot. I already replaced it but still very hot
 
2informaticos

2informaticos

Administrator
Staff member
"Y5010 is not oscillating and is at a steady 1.578V"
I mean oscillates on o-scope...
1.5V is close to normal value, but DC voltage cannot assure you for proper oscillation.

"3V3_S5 0v"
This doesn't depend by PCH, is controlled by SMC.

If U7200 heats after UC, probably some traces got broken, or some components fall out.
UC without sweep function is a danger for logic board, if you let it various minutes in the same position; read about "hot spot" for cavitation.
Check for any short (L7220/60 maybe) and missing caps (C7220/60?) around U7200.

Never power up a board after replacing of a hot component.
Think first, why was getting hot???
There could be other reason...
 
2informaticos

2informaticos

Administrator
Staff member
U7200 MUST have a reason to get hot.
If changed and still the same, obviously is not the culprit.
Check for short/low resistance on VREG3/5, VIN, VREF, L7220/60...
Post its voltages.
 
K

Kyle93

Active member
also once in awhile when you plug board in it will make a ticking noise for a couple minutes. Doesn't happen all the time
 
K

Kyle93

Active member
I apologize I see the values on the schematic.
I apologize I see values on schematic now

VREG 3 0v

VREG 5 0.50v

vin 12.60V

VIN 3 0.31v
 
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