macbook A1466 no green light

[sassan]

Hello,

i have a macbook air A1466 820-00165A with no green light,when trying to turn it on the fan spins for short time then stops ,no display.

Any suggestion please.

Thank You.

[mon2]

Re: macbook A1466 no green light

1) Is the adapter an Apple original? Is it a known good working adapter ?

2) Attach the adapter. Post the voltages from the attached locations. Meter in volts mode, black lead on ground. Red lead on each requested location.

3) Volts on L7095, pin 2 = PP3V42_G3H. This rail must be 3v42 or close to this value.

[sassan]

Re: macbook A1466 no green light

1) Is the adapter an Apple original? Is it a known good working adapter ?

2) Attach the adapter. Post the voltages from the attached locations. Meter in volts mode, black lead on ground. Red lead on each requested location.

3) Volts on L7095, pin 2 = PP3V42_G3H. This rail must be 3v42 or close to this value.

Location 1 = 8.57V
Location 2 = 15.09V
Location 3 = 14.83v
Location 4 = 3.427v

Thank you .

[mon2]

Re: macbook A1466 no green light

Is the missing green light on the magsafe power adapter head?

[sassan]

Re: macbook A1466 no green light

Is the missing green light on the magsafe power adapter head?

yes,it's missing.

Thank You.

[mon2]

Re: macbook A1466 no green light

1) Power down. Meter in resistance (ohms) mode. Black lead to ground. Red lead on (usually white in color) fuse F7140, pin # 2. Value in ohms ?

You may have a bad cap on the logic board that is causing a very low resistance (CPU rails are ok to be low in value). A high current draw occurs on the respective rail and the local power supply then shuts down to prevent damage.

Review each coil for each power rail on the logic board and post their resistance to ground. All with the power removed.

If the resistance for each coil to ground is ok - then a bad cap is not the issue so continue with...

2) Post your voltage for PP5V_S4RS3 rail @ L7520, pin # 1.

3) Confirm the voltage reaches the connector J7000, pin # 3.

4) The LEDs onboard the magsafe head are based on the Maxim (aka Dallas) Semiconductor 1-wire interface. Using a single wire / pogo contact pin, communication occurs between the magsafe adapter and the host logic board.

After a handshake occurs between these 2 parties, the magsafe power adapter will power up to the max voltage to power the logic board.

Check that the pogo pin contacts are clean on your paddle (LIO) board that mates with the magsafe adapter. This is very important. Recommend to use a cotton swap or similar with alcohol to clean up each contact.

Also attempt to power up the logic board without a battery. Does this allow for the magsafe light to turn on?

5) Check that the bridge cable between the main logic board and this LIO board is solid and with no corrosion. These cables are relatively low cost to replace (821-1722-A).

6) The LIO board may be defective. Not aware of any schematics for this paddle board.

See here:

http://www.righto.com/2013/06/teardo...f-magsafe.html

The power cycling issue to me would indicate a power supply issue on the main logic board. The logic board does not remain powered up long enough for the host to communicate with the magsafe power adapter to enable the higher adapter voltage which also is the same 1-wire interface to change the LED colors.

[sassan]

Re: macbook A1466 no green light

Hello,

i cleaned the bridge cable between the main logic board and LIO board ,now i get the orange light on the megasafe with and without the batttery .trying to switch it on same thing,the fan spins then stops,no display no nothing.

Thank you.

[mon2]

Re: macbook A1466 no green light

Post the values from the earlier requests. Interested in each coil (grey inductors on logic board) resistance to ground with all power removed. A very low resistance will denote a bad or shorted caps which are quite common.

[sassan]

Re: macbook A1466 no green light

Post the values from the earlier requests. Interested in each coil (grey inductors on logic board) resistance to ground with all power removed. A very low resistance will denote a bad or shorted caps which are quite common.

OK,
here is what i did so far:

yesterday when i cleaned the bridge cable between the main logic board and LIO board ,the magsafe light is back on(orange),i plugged the battery left it until the battery is charged then became green.

when i press the power button the fan spins the immediatly stops (same thing on the battery alone).

L7310 L7320 23,4 ohms
L7630 192 ohmS
L7430 329 ohms

L7520, pin1= 0volts,

Thank you for your help.

[mon2]

Re: macbook A1466 no green light

L7520, pin1= 0volts

Resistance to ground on L7520, pin 1 ?

Voltage on R7551 = Enable for this rail via pin # 4, U7501 ?

voltage @ P5V_S4RS3_DRVH ?

voltage @ P5V_S4RS3_DRVL ?

voltage @ PPBUS_S5_HS_OTHER_ISNS ?

[prof6]

Hi all,

What was the solution?
I have Exactly the same issue.
no green light, fan spins and immediately stops. All voltages are ok. I did not found any short on the voltage lines.
If i press power button fan starts spin and stops, like when i connect the charger.
What else could it be?


Thank you in advance!

[mon2]

Review this flow chart:

https://logi.wiki/index.php/G3_to_S3..._and_Broadwell

[dellxps15]

check if cpu vcore comes when fan spin.

[prof6]

When the fan spinning(about 1sec) i measured the following(Resistances measured when charger or batt. not connected):

Schematics net names || Measured Voltage || Measured on which coil || Comment or condition

PPVCC_S0_CPU = 1.762V (L7320 & L7310) Resistance is 122.8ohm
PP1V05_S0 = 1.069V (L7630) Resistance is 183.1ohm
PP1V2_S3 = 1.203V (L7430) Resistance is 628.1ohm
PP3V3_S5_REG_R = 3.335V (L7560) Always ON! Resistance is 2.631kohm
PP5V_S4RS3 = 5.105V (L7520) Resistance is in Mohms range, no short.
PPBUS_G3H = 8.58V (L7130) Always ON! Resistance is in Mohms range, no short.
PP15V_TBT = 0V (L3095) Resistance is in Mohms range, no short.
PPHV_S0SW_LCDBKLT = 0.1V (L7701), no LCD connected, resistance is 3.71kohm
PP3V42_G3H = 3.416V (L7095) Always ON! Resistance is 6.48kohm

I am not familiar yet about repairing Apple's logic boards instead of an other laptop motherboards. So thats why i am really appreciated your kindly helpful tips/hand.

JOhn.

[mon2]

Can you start in SMC bypass mode?

[dellxps15]

fan spin for 1 sec then stop and no loop or it do fan spin every tot seconds ? when u plug magsafe, fan spin then stop and stay in stop mode also if u wait like 60 seconds ? check bios area, bios spi connector for corrosion, check cpu data lines. also check r1270, r1275 also l1290, l1275 and so on in that area

[prof6]

Hello,

Sorry for the late reply, it was a busy weekend i had no time to step forward about it.

I found that the flex cable's connector(between logic board and dc input board) was damaged by the previous owner when battery changed by himself.
SMC_BD_ACOK line was damaged/shorted, and some others too.
I cannot repair that, but fortunatelly at the flea market i bought exact same model macbook air which is works like a charm.
Even if i just changed the flex cable it wasnt enought.
So, when i changed the flex cable and the DC input PCBA as well, the charger light works, sometimes it is orange even if the battery does not connected, but works.
But the sympthome is the same, fan spins 1 sec than turns off. if i press power button, fan spins 1 sec. than turns off. i can repeat this endlessly.
I never heard the SMC bypass before, so based on mon2 suggesion i tried it, and it is fully works, the fan spins 100% and everything works.
Dear Dellxps15, thx for the tips, it is looks like the bios/prom data lines are fine.
So what else could be?

I guess the failure comes from the damaged flex connector, i mean some data lines pullups or pulldowns damaged permanently or somehing like that.
If i can start the macbook in this SMC bypass mode, is there any kind of diagnostic tool(SW) to be able to see what is causing the start inhibit?

Br,
JOhn.

[mon2]

If SMC bypass works then the SMC device may need to be flux and reflowed. Search for articles / YT videos on this topic. Years ago, piernov suggested the same to me when first starting with board repairs and of course it worked well. The solder balls sometimes break under the SMC device. Only if you are comfortable with the process, consider to reflow the SMC with hot air but low air pressure else the parts will go flying into the next room.

https://www.youtube.com/watch?v=4-S8...annel=ResetLab

Proceed at your own risk. You will need to remove the edge glue with a low temp before reflowing the chip at a higher temp.

[dellxps15]

easy question.... are sensing resistor ok ? r7121 r7122 (10omh each) u can check pin 27-28 of u7100 if it's 20 omh. also check r7151 r7152.

[prof6]

Hi,

SMC reflow done. nothing has been changed, same sympthome.

R7121, 7122, 7151 and R7152 checked, all are OK. Shunt resistors are OK as well.
The board charging the battery while i replaced the DC input module.