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820-02020 liquid damage

K

Kyle93

Active member
This arrived with liquid damage and no power. After cleaning up and replacing bad caps and resistors board is back to 20v and partially booting but no there is no image on internal or external.

When external plugged in with internal lcd disconnected the caps lock light comes on. Heatsink is not getting warm.

LPD_INT_HPD is present 1.8V

What should be checked next???
 
2informaticos

2informaticos

Administrator
Staff member
So Caps Lock light reacts normally, or just stays on?

Did you note liquid signs on video, or backlight areas?
 
K

Kyle93

Active member
Caps Lock light reacts normally, has the ability to turn on and off.

Yes there was liquid in backlight area. Already replaced backlight driver but there was no change.
 
2informaticos

2informaticos

Administrator
Staff member
If LPDP_INT_HPD stays high, internal LCD is detected.
However, missing internal and external video points to CPU problem.

No USB activity, nor Caps Lock light reaction, when internal LCD is connected?
 
K

Kyle93

Active member
Have not checked USB activity but Caps lock light reaction is the same when internal LCD or only external is connected
 
2informaticos

2informaticos

Administrator
Staff member
"When external plugged in with internal lcd disconnected the caps lock light comes on."
I was thinking may have a problem when internal LCD is connected.

Check diode mode to ground at LPDP_INT lines; on the M1 side of series capacitors.
 
2informaticos

2informaticos

Administrator
Staff member
You have 10 caps there; don't forget CP620/21.
Need to check the value on the left side, toward M1 chip.
 
K

Kyle93

Active member
Checked the remaining values and all look good. Looking closer at internal lcd I do see a apple logo for the first few seconds after plugging in.

PPVOUT_LCDBKLT 0V not shorted

LP800 pin 5 only 0.628v pin 17 1.8v

QP800 pin 2 0.060v pin 4 12.60v
 
2informaticos

2informaticos

Administrator
Staff member
"LP800 pin 5 only 0.628v pin 17 1.8v"
Did you mean UP800 missing 5V at pin 5?
Check diode mode to ground there and replace RP844.
 
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