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820-3115 no power

K

Kyle93

Active member
Board had mild water damage. All components were replaced that had corrosion, smc was reflowed and board went in uc afterwards. It worked for a few minutes and then died.

Currently I have a green light and all power rails up to pp5v3_s3 is missing. I already checked and replaced u7200. pin 16 is 16v. what should I check next?
 
D

dukefawks

Administrator
You saw the original water damage. The fact that it worked and then died usually point to a corroded resistor or corrosion under a chip. It all depends on where the corrosion was.
 
K

Kyle93

Active member
While it was working i attempted a smc reset and thats when it died. Do I need to replace smc again?
 
D

dukefawks

Administrator
SMC_RESET will not hurt anything like that. It is corrosion under some chip or a corroded resistor/trace. Again, it all depends on where the corrosion was.
 
K

Kyle93

Active member
Can someone assist me with this board with more suggestions? recap I have all power rails up to pp5v_s3. Dont have a short to ground pin 16 of u7200 is 12.60v
 
2informaticos

2informaticos

Administrator
Staff member
Do you get any pulse at L7260, or other secondary supplies?
Apart of L7220, which must have stable 3V3...

Post SMC_ADAPTER_AN, PM_BATLOW_L, PM_SLP_SUS_L.
Check 32KHz clock to SMC.
Try to start shorting power pads (R5015/16) and check if PM_PWRBTN_L reacts.
PM_RSMRST_L should rise first.
 
K

Kyle93

Active member
0.007V on l7260. doesnt move from there

SMC_ADAPTER_EN 0V

0.427 32KHZ CLOCK pin 12 u2600

shorted pads and PM_PWRBTN_L didnt react

PM_RSMRST_L didnt react
 
2informaticos

2informaticos

Administrator
Staff member
"PM_SLP_SUS_L"???

Check PPVRTC and all 4 (four) RTC signals.
SMC crystal Y5010 oscillates?
32KHz present at SMC input?
SMC_ONOFF_L is high?
 
K

Kyle93

Active member
PM_SLP_SUS_L 0V

RTC_RESET_L 3.482V

PCH_SRTCRST_L 0.412v

PCH_INTRUDER_L 3.199v

PCH_INTVRMEN_L 3.338V

Do not own a oscilloscope to check Y5010 oscillating

How do you check for 32KHz?

SMC_ONOFF_L 3.487V
 
J

jadao

Member
PCH_SRTCRST_L should be higher around 3.3V
Check if R1802 measure ok, hard for a 20 kohms to go high but still possible it happens. Check also if any corrosion underneath the resistor ( I mean corrosion on the pad). Check also C1802.
See if any short on pin 2 of R1802.

It could be a pch issue also... I had an smc with SMC_RESET_L low stuck at 1.4v, but no short at all, when I heated smc SMC_RESET_L went 3.3v and back to 1.4v when cold...
 
2informaticos

2informaticos

Administrator
Staff member
"PCH_SRTCRST_L 0.412v"
PCH is kept in reset, no need to measure oscillation anymore.
C1802 is the first suspect here.
If not, bad PCH (hope not the case)...
 
K

Kyle93

Active member
Ok I have cleaned the pads up and replaced c1802 and r1802 but still same results. First time I have run into a board with this issue, however I have the ability to replace the pch. Does anything need to be done to the bios after pch is replaced?
 
2informaticos

2informaticos

Administrator
Staff member
Of course, new PCH requires clean ME region...

Did you check resistance to ground on PCH_SRTC_RST_L?
Check it again with removed PCH and compare values.
 
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