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820-00165 - computer dropped and will not switch on G3H voltage low

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leonattpcs

New member
I have tried a new battery and does not do anything. When connecting power with the battery connected or not connected the light on the charge connector goes green then red, no fan spin. I have found r7005 has dc in voltage r7006 only has 1.3v. So is G3H voltage not being boosted or being dragged down by something?
Thanks
 
smiba

smiba

New member
Alright so from your explanation I get that you have a low voltage on PPBUS_G3H?

How does U7100 area look like?
Fuse (F7140) Not blown?
Resistance to ground on PPBUS_G3H in Ohm?
CHGR_RST_L High?

Check if PP5V1_CHGR_VDD and PP5V1_CHGR_VDDP is there
 
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leonattpcs

New member
Around u7100 looks good, f7140 not blown
resistance to ground on PPBUS_G3H is 166 ohms
CHGR_RST_L beeps @ 3ohms
PP5V1_CHGR_VDD there
PP5V1_CHGR_VDDP there
c7150 beep like it is a filter though...
 
D

dukefawks

Administrator
CHGR_RST_L beeps @ 3ohms
PP5V1_CHGR_VDD there
PP5V1_CHGR_VDDP there
c7150 beep like it is a filter though...

Are you measuring with power applied??
 
smiba

smiba

New member
CHGR_RST_L should most definitely not be 3ohm to ground

Are you absolutely sure this is the case with no battery and charger plugged in? Because then I'd say replace U7100

Also do not measure resistance with the power applied unless there is a reason to do so
 
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leonattpcs

New member
OK so CHGR_RST_L is now .555 ohm to ground... no idea how, red probe on ground then black probe on each side of the component I am changing u7100 and will test again
 
L

leonattpcs

New member
Just an update, I have fan spin after replacing u7100 and the voltage that used to be 1.3 v is now 8.2v, am rebuilding the computer to see if it will work properly.
 
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leonattpcs

New member
OK so the problem is still there even with all voltages back. Tried another battery no change. One thing I have noticed:
Q7155 pin 1,2 3 are at 8.2v, pin 4 is 8.18
Pin 5 is 0.24
I am thinking pin 5 should be be the same as pin 1,2,3 and 4 so the battery can charge?
 
G.Beard

G.Beard

New member
It was dropped. Who knows what little pad could be hanging on by a thread, or not hanging on at all.
I don't have the experience of some of the guys here but what I do do (lol, do do) is refuse to touch dropped machines.

Even if you can fix all rails and get a fan spin. What if it goes beep beep beep at the end of it all?
 
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leonattpcs

New member
Well I am thinking it is something to do with pin 4 on Q7155 due to where it comes from which is u7100. I am thinking it is not being told to charge the battery.
 
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leonattpcs

New member
OK so looking at my own MacBook Air, pin 4 is less than 1v therefore I am thinking the voltage changes depending on whether the computer should use the battery or not, so where to find what tells that voltage to change...
 
smiba

smiba

New member
What is the issue at the moment? Can you confirm the system boots? (You said it had fan spin)
 
smiba

smiba

New member
Trouble on SMBUS_SMC_5_G3 datalines, make sure U7100 is well attached and try known good battery.
Check if R7380 and R7381 are about 2kohm. Also unlikely but just to be sure, check if R6950 is not closed / within specifications

Check SMBUS_SMC_5_G3_SCL/SDA voltages are not above 3.4V with the battery plugged in, because that would mean the battery is killing the SMC.

If this all alright, the dead U7100 probably killed the SMC. Replace SMC
 
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leonattpcs

New member
Hi, after checking that with a known good battery the SMBUS_SMC_5_G3_SCL/SDA voltages are unstable between 0.9v and 3.4v, the battery sense line is the same type of voltage as well. I will replace u7100 again, and if no change then will replace smc
Thanks
 
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