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A1425 (820-3462-A, I think) with most power rails fluctuating.

J

joshAU

Member
Hi all.
I have a Macbook Pro A1425 that gets an orange light, no fans or other signs of life.
No signs of overheating.
Very slight amount of corrosion, all located on bottom side edge of the board (when installed in MB).
Between L7560 and across to around U6990.
C7527 looked the worse -bad corrosion, and actually broke free while cleaning it.

I think the board is a 820-3462-A, and it does indeed look identical to the boardview, I just cannot find the model on the board itself.

The only consistent power supply is PP3V32_G3H, which is a stable 3.41volts.
All the rest were fluctuating.

I suspect there is a short, and the PSU or board itself is cycling on and off to protect it... and hence why nothing is getting hot enough to notice.
Any suggestions on which rail/area to check first?
Thanks for any help you can provide.

PPDCIN_G3H fluctuating slightly 14.75-15.15V
PPBUS_G3H fluctuating slightly 15.09-15.5V
PP3V3_S0 Fluctuating 0.10-1.0V
PP3V3_S0 Fluctuating 0.20-1.0V
PP5V5_S0 0v
PP5V5_S5 3.9-5.02V
PP3V42_G3H 3.41V
 
2informaticos

2informaticos

Administrator
Staff member
"PPBUS_G3H fluctuating slightly 15.09-15.5V"
Looks like shorted Q7030, change it.
Be sure R/C7025 are both good, as all traces around U7000.
 
J

joshAU

Member
Thanks 2inforaticos.
I appreciate your help, once again.

OK, I desoldered Q7030 and checked the desoldered chip.
All pins/pads on the removed Q7030 show essentially zero ohms resistance, so you were correct re it being shorted.
R7025 shows zero Ohms.
C7025 seems OK.

I did find a tiny bit of corrosion near U7000, primarily on C7000, but otherwise area around U7000 looks good.

I don't think I have the same board to grab a replacement Q7030 from. :(
I may have to order one in.
 
2informaticos

2informaticos

Administrator
Staff member
You should find it on other MaBook boards.
Just check schematics of the scrap boards available.
The pin layout is the match you search for.
 
J

joshAU

Member
Hi again 2informaticos, and thanks again for your help.
Sorry for the delayed reply - first day back at work since the mid December.

I replaced Q7030 and now have the unit booting. :)

One thing that isn't working is the left Shift key.
HOWEVER, the SMC correctly resets by pressing the left Shift, Control, Option and power buttons - i.e. the magsafe light changes from orange to green and back to orange, so it must be at least partially working?

However, I notice that it is booting in Safe mode most of the time?
I did an SMC reset and it booted normally, but seems to intermittently boot into safe mode.
I assume that the shift key may be stuck down - although when in OSX, the characters type in lower case unless I press the right Shift?
Once in OSX, after logging in, the red Safe mode up the top right disappears, I only see it on the login screen.
I'm not familiar with safe mode as to whether this is standard behaviour.

Short of replacing the keyboard/kb& top cover, any suggestions?
Thanks again for any help and advice.
 
J

joshAU

Member
Hi again 2informaticos.

Thanks for the link to the keyboard tester.

Yes, the left shift doesn't respond.
However using it to do an SMC works, so not sure whats going on there.

Either way, customer is happy to take it as it is - so job closed... for now at least. :)

Thanks again for your help.
 
2informaticos

2informaticos

Administrator
Staff member
Possibly issue with U5750.
It processes WS_LEFT_SHIFT_KBD, because generates SMC_TPAD_RST_L.
But may fail WS_LEFT_SHIFT_KEY generation, or there is broken trace between U5750 and U5701.
 
J

joshAU

Member
Thanks for that additional information.
That makes sense....if it comes back I'll have a look at U5750, and or traces between it and U5701
Thanks again.
 
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