820-00165 liquid, no fan spin but orange light [solved]

nik1981

Member
I have an 820-00165 with no fan spin after liquid damage.
Orange light and SMC reset goes green and back to orange.

Liquid damage around U5110 cleaned up.

PPBUS_G3H = 8.52v
PP5V_S5 = 4.98v
PP3V3_S5 = 3.32v
PM_SLP_S4_L = 0v
SMC_PM_G2_EN = 3.4v
PPVRTC_G3H = 3.3v
PM_DSW_PWRGD = 3.4v
PP3V3_SUS = 3.301v
PPBUS_S5_HS_COMPUTING_ISNS = 8.53v

R1300 pin1 = 3.302v - pin2 = 3.296v
R1301 pin1 = 3.302v - pin2 = 3.030v
R1302 pin1 = 3.302v - pin2 = 3.208v
R1303 pin1 = 3.302v - pin2 = 3.296v

JTAG obviously removed, replaced the burnt LVDS connector.

I’m not sure where to go from here.
 

2informaticos

Administrator
Staff member
"PM_SLP_S4_L = 0v"
No pulse at all when trigger SMC_ONOFF_L

Did you try to start in SMC bypass mode?
PM_BATLOW_L is high, original Magsafe 2 charger?
 

nik1981

Member
OMG! I've been testing with the wrong charger. Such a noob sometimes, I should have known better.

Now turns on, fans normal, CPU heats up but nothing on the screen. No backlight or screen activating
 

nik1981

Member
I don't have a way to test external at the moment but it does power a USB mouse.
Tried another screen assembly also
 

nik1981

Member
On U8300 I get 0v on pin 1 (EDP_PANEL_PWR) but I'm getting 3.3v on pin 2 and 3

R1431 is the pull up resistor for EDP_PANEL_PWR and its supposed to be 100k but tests as 82k on the board.
Do you think this might be an issue or is something pulling that down a touch while its attached to the board?
 

2informaticos

Administrator
Staff member
I didn't ask for USB power.
Does the mouse get steady light if you disconnect/reconnect it when board is turned on?

Looks like no image, why do you search for backlight then?
DP_INT_HPD goes high?
Check in the first 10s, if pulses at least...
 
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nik1981

Member
The light on the mouse I use is bright and then dims after 5 seconds. I think this is normal as it does it on my iMac just the same.
DP_INT_HPD is 0.00v I can't see any pulses or maybe my multimeter is too slow.
 

2informaticos

Administrator
Staff member
"DP_INT_HPD is 0.00v"
You vannot get image, nor backlight.

Use bootable pendrive with Link LED; if flashes, there is USB activity 100%.
 

2informaticos

Administrator
Staff member
Start with bootable USB connected and internal SSD removed.
The pendrive MUST flash continuously, like charging OSX...
 

nik1981

Member
I've tested with two seperate USB that I know will boot. Neither of them flash continuously like it is booting the OS.

Tried with internal SSD removed also, don't think it is trying to boot.
 

2informaticos

Administrator
Staff member
As I imagined, no USB activity.
Your board doesn't boot, or gets stuck.
There is no reason to search for video.

Try known good BIOS...
 

2informaticos

Administrator
Staff member
Do you get PLT_RESET_L?

Did you swap the BIOS chip from working board?
Don't you have a programmer to write a known good (clean ME) BIOS?
 

nik1981

Member
PLT_RESET_L is 3.3v

The BIOS chip was from a dropped 820-00165 (dead CPU) so the bios should be okay but I suppose it could be also faulty.

The only programmer I have is SOFI SP8 for doing bios locks on the old A1278/A1286 boards. I haven't programmed the bios on A1466 before, sorry.
 

nik1981

Member
Tested all SPI Bus Series Termination resistors

R6110
R6111
R6112
R6113
R6118
R6119

R6114
R6115
R6116
R6117

R6120
R6121
R6122
R6123
R6130
R6131

R6133
R6132
R6128
R6127
R6126
R6125

All test as schematic, can't see any issues with traces on the microscope.

Going to reball the SMC now
 
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