A2141 820-01700 - 5v / .454a all four ports

[tawnytim]

Have a A2141 no power complaint. Board is out, I'm measuring 5v, .454a draw on all four ports. Voltage @ F700 jumps between 7.87v and 8.77v.

What can I check next?

 

[2informaticos]

First of all, welcome to the forum!

Any history available?
Be aware, this machine requires 96, or 140W charger.
Try with battery connected too.
Remove both F7000/1 and check C7050 voltage.

 

[tawnytim]

Hey! Thanks for the response! No history available unfortunately. Although my customers tend to purposely leave out details it seems. I am using an OEM 100W apple USBc power adapter for reference. With F7000/1 removed, I am getting 12.32v @ C7050.

 

[2informaticos]

Now resolder the fuses and check if 3V3_G3H_RTC is stable.
What about PPBUS_G3H voltage with both charger and battery connected?

 

[tawnytim]

Now resolder the fuses and check if 3V3_G3H_RTC is stable.
What about PPBUS_G3H voltage with both charger and battery connected?

3.384v steady at C3100 which is 3v3_G3H_RTC_X

 

[2informaticos]

Please, don't quote an entire message, visible few centimeters above.

The expected SLPS2R and AWAKE voltages stable too?
Is the machine recognized into DFU mode?

 

[tawnytim]

I'm looking up SLPS2R and AWAKE in the boardview but there are many. Can you tell me a preferable measurement point? This device does not show up in Apple Configurator.

 

[2informaticos]

Look at the small coils surrounding U7800...

 

[tawnytim]

OK, none are stable. Some have 0-.8v fluctuations and others have 0-1.1v fluctuations.

 

[2informaticos]

Did you test with both charger and battery connected?
Also try another known good 96/140W charger.

 

[tawnytim]

It was with the battery and charger connected. I don't think I have another adapter. This is the one I always use. I'll order one and touch base again when it arrives and I test.

 

[tawnytim]

Verified, battery connected, brand new OEM 140W power adapter.

 

[2informaticos]

U7800's LDOs fluctuate too?
Look at page 76.

 

[tawnytim]

C7905/6/14 all fluctuating.

 

[2informaticos]

Check voltage on both sides of R7900.

 

[tawnytim]

This is with battery now disconnected, since this item is on the back side of the board. R7900 has constant 3.38v on both sides.

 

[2informaticos]

Check diode mode to ground on all coils.
Compare with good board, if possible.
If not, use online reference table.

OpenBoardData Project

 

[tawnytim]

Just power supply coils, or every single coil on the board? That's maybe hundreds, so I'm assuming you mean just the power supply coils. Can you confirm?

 

[2informaticos]

I meant power supplies coils, of course.
Don't forget the ones from SSD areas.

 

[tawnytim]

Here you go!