Hi friends need help
Macbook pro a1278 motherboard issues
No green light No fan runs
How to solve it
Macbook pro a1278 motherboard issues
No green light No fan runs
How to solve it
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Re: Apple Macbook pro A1278 No green light no fan
Hi. What is the 820-xxxx logic board number?
Are you using a known good power adapter?
What is the history of the computer? Liquid damage?
Just stopped working? -
Re: Apple Macbook pro A1278 No green light no fan
Yes am using a original adapter it is working fine i have checked with another macbook.
Motherboard number is 820-3115Comment
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Re: Apple Macbook pro A1278 No green light no fan
Review page # 3 of the schematics. This page details the ordering of the power rails. Check each stage and post the first rail that is missing.
So for example, check that the DCIN from the adapter is reaching the fuse @ F6905. Then check AFTER this fuse to confirm the fuse is not blown.
Next, check the output of the dual diode @ D6990 (pin 3). Voltage here ?
Only if the voltage @ D6990 is high enough, then U6990 can perform its job of creating the required 3v42 rail.
Measure and post the voltage @ PP3V42_G3H_REG.
Voltage of PPBUS_G3H ?Comment
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Re: Apple Macbook pro A1278 No green light no fan
Hi
Thanks for the reply it very helpful
i have checked the voltages of the Fuse D6990, U6990 they are getting 16.8v
i dont know what to do as am very basic learner of macbookComment
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Re: Apple Macbook pro A1278 No green light no fan
Measure and post the voltage @ PP3V42_G3H_REG.
Voltage of PPBUS_G3H ?Comment
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Re: Apple Macbook pro A1278 No green light no fan
PPBUS_G3H from 0.8 it is decreasingComment
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Re: Apple Macbook pro A1278 No green light no fan
See attached.
1) Leave meter in DC voltage mode. Check the voltage @ F7040, pin # 1.
What is the reading ? Is it still ~0v8 ?
If the voltage is not the same as on F7040, pin # 2 then F7040 is blown and needs to be replaced.
2) If the voltage is about the same on both sides of F7040, then there is a fault on this switching regulator and may be due to a short circuit on the rail.
Remove all power (no adapter / no battery).
Meter in resistance mode (2k is ok but can be higher).
Red meter probe on F7040, pin # 1. Black meter probe on ground. What is the reading ?
Repeat for F7040, pin # 2.
This test is to check if there is a part that has failed (ie. shorted capacitor) and causing this power supply to shut down.
Update:
Attaching where to locate PP3V42_G3H_REG . Measure and post this very important voltage rail. It should be ~3v42 for this logic board.Attached FilesLast edited by mon2; 11-30-2021, 09:51 AM.Comment
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Re: Apple Macbook pro A1278 No green light no fan
same voltage on f7040 both pins
i measured resistance it is showing 0 ohms and no short hereComment
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Re: Apple Macbook pro A1278 No green light no fan
The resistance measurement should be RED meter probe on fuse pin & BLACK meter probe to ground.
Using this setup and meter on 2k or higher - you are reading 0 ohms ? If yes, then you DO have a short to ground.
Please confirm.Comment
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Hi, I have a MacBook pro A1278 (820-3115-B) that has green light on the charger and does not turn on, the fan does not spin.
The voltages in the SMC seem correct. I have made voltages measurements on the main coils and I put their measurements here:
L7220..........3.3V
L7260...........5.12V
L7330..........1.5V
L7030..........12.67V
L3895..........2.5V
L7760..........1.80V
L9701..........0V
In the following coils they give me continuity with ground, which seems strange to me:
L7550,L7510,L7520........ 0V
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Hello, greetings everyone. I NEED YOUR HELP
I got this macbook that doesn't turn on, I don´t have a green light, but it's got a fan spin for a few minutes and after it's off.
This macbook comes in without damage from liquid spill.
The story of the Mac is that the screen closes and left without use for two days. Then they try to turn on and it won't turn on. Then they connect the charger and it doesn't give light.
It´s a Macbook Air 2017
Please help me understand how this works... Correct me if I'm wrong in my way of... -
I have a 13 inch MacBook Air 2017 that does not show any life, however, there is activity from the MagSafe light going from green to orange and staying. Normally, this battery works perfectly fine and it can actually charge the battery as if I were to leave it alone it would change to just green, however, this thing does not boot up at all, I was told the computer was at 30% and then it randomly shut off.
Some voltages:
PPBUS_G3H - 8.5V
SMC_PM_G2_EN - 3.42V
PP3V3_S5 - 3.32V
PP3V42_G3H - 3.42V
PPDCIN_G3H - 15.18V
PP5V_S5 - 5.04V
PP3V3_S5_REG_R... -
Hello there. I've got an issue with my Macbook Pro A1425 820-3462 with no green/orange light when plug in. Also I was unable to boot with the battery plugged in. When I change the DC-in board to another spare one I had, it show orange light and boot up with fan spinning, without the battery plug in. But it will randomly just not showing the magsafe light and the system become slow and the fans just when erratic all of sudden
Here's the voltage I've measured based on the guide I've read :
Original DC-in board (no green/orange light, no fan spin) :
SYS_ONEWIRE... -
Hi
I have an 820-2610-A motherboard that has no green light.
I have noticed is when I do a SMC reset the light on the Magsafe blinks.
From My understanding, the sys onewire circuit is responsible for the green light on the magsafe
The sys onewire circuit on this model and others is more involved
I was hoping if anyone knows about this and how it works, can reply and let me know
I know this is an old model but I am sure there are people who still works on these or knows about them
I get 1.1v on the C7771 capacitor and will replace...
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