820-00165 - No green light. SMC_RESET_L is 1.15v

Mattpd

New member
Dead. No LED and no fan. No obvious liquid.

SMC area looks good.

U5110 looks good.

U7100 area looks good.

PPBUS_G3H is only 8.18v

SMC_RESET_L is always 1.15v

If I jump R5100 with tweezers the fan starts and green light comes on.

Measuring R5100 I am only getting 80k instead of 100k. But I am also measuring it on the board, so maybe that's wrong.

Should R5100 still measure 100k even in circuit? Anything else to check?
 

2informaticos

Administrator
Staff member
R5100 is good for sure.
Clean J6100, if looks ugly; can be removed.
Remove U5110 and check if SMC_RESET_L goes high.
If not, remove R7100 and check again.
 

Mattpd

New member
J6100 looks good.

I removed U5110. SMC_RESET_L is still low, but for some reason green light comes on now. No orange light with battery connected though and no fan.

I also removed R7100 but SMC_RESET_L is still low, but it's higher than before. It was around 1.15v but now around 1.6v.

EDIT: No green light anymore after unplugging for a while.
 
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2informaticos

Administrator
Staff member
Change R5100.
If still low, reflow SMC.
Last option, change SMC; you can reballing it first.

Put back U5110, if is not the culprit...
 

Mattpd

New member
This thing worked for a few days then quit.

I reflowed SMC and it worked for a few more days but now quit again.

Back to the same problem. R5100 now measures low and SMC reset is 0.7v. I can still bridge R5100 and make fan start.

I suspect it needs new SMC although there was never any water damage. Thoughts?
 

Mattpd

New member
I just pushed on the opposite side of the board from SMC and it made green light come on. Still no fan.

Must be ball under SMC right?
 

Mattpd

New member
This thing is still giving trouble.

I did a reball on SMC and the job went very smoothly. I tested it over the weekend by powering it up and down at least 10 times.

Now today it's back to no green light.

Is it worth trying to source a new SMC or is there something else going on?
 

Mattpd

New member
It looks like I have a new problem now. SMC_RESET_L is non existent and PP3v42_G3H is short to ground at 1 ohm.

I won't have access to my DC power supply or hot air until later today, but noticed that with Magsafe connected that U7090 gets kind of hot, but not extremely. Hot enough to evaporate ISO alcohol though. Maybe he is the problem?

I just hope the SMC hasn't failed because I don't have any more. I would think my reball job was good since the machine behaved well for days after doing the job, but maybe not...
 

Mattpd

New member
Thanks for the reply. The short is actually gone now and board is currently working again.

Yesterday I had confirmed with two different meters that it was short at around 1 ohm.

Then I attempted to use DC power supply to heat up the short. I limited it to around 1.5A touched the short.

NOTHING happened. Power supply didn't budge. No fan, no noise, no spark and no amperage. It was like my power supply wasn't connected at all.

I was confused about what was happening so I checked for the short again. Now it's gone.

Did the short burn out instantly when DC power was connected? Like a small fleck of solder maybe?
 

2informaticos

Administrator
Staff member
This symptom points to some cap with partial short.
The short can come back in the future, as that cap is corroded.
 
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