820-3747 liquid


New member
Hi! I have a liquid damage Air that turns on occasionally.

The damage was minor and in these areas:
JTAG - Removed.
U1900 - Replaced and traces checked.
U7501- Replaced and traces checked.
U7701 - Cleaned
U3220 - Cleaned
U4430 - Replaced

Here are voltages
PPBUS - 8.5
PP3V42 - 3.42V
PPRTC - 3.3
PP5v_s5 - 5V
PP3.3v_S5 - 3.3
PP5V_s4 - 0
PP3V3_s4 - 0
PPVCC_S0_CPU - Fluctuates between .57V and .85V when fan spins.
All_SYS_PWRGD - 2.57V When fan spins.

Obviously missing PM_SLP_S4_L

Any direction will be greatly appreciated.
Have a good one!


Staff member
"Obviously missing PM_SLP_S4_L"
Not true.
It pulses at least, if fan spins...
The fan needs 5V_S0.

"All_SYS_PWRGD - 2.57V When fan spins."
That means all the secondary coils pulse too; maybe not the CPU ones, check that.

Check U1950 area.
Pins 7 & 3 pulsing too?


New member
Thank you for your reply,

L7630 fluctuates between .003V and .004V.
L3095 starts at .003V and stops at .040V
L7520 - 0V
L7430 - 0V

Pins 7 & 3 of U1950 are not pulsing.

Thank you!
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Staff member
Use o-scope for fast pulses, normal DC multimeter doesn't catch them.

Will be good to know if PM_SLP_S3_L pulses too.
Those mV you mentioned don't tell nothing; pick an o-scope...


New member
Ok, thanks.

Update : This one may hang for a bit due to the fact that I don't have a scope.
Thanks for your input.
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