Macbook A1464 dead

[mcplslg123]

Model :Macbook A1464
mb: 820-00165

History:
It came complete dead. Was full of dust and corroded near Spi rom area. Cleaned thoroughly with IPA, removed eeprom chip and restored tracks,resistors as per schemtic. U6101 was also heavily corroded and i've restored it properly. Observed under microscope, rest of the mb seems clean.

It worked like a charm after all these steps, delivered it to customer, it came back again dead but this time magsafe light turns green/orange and it does switches with pulses. I've powered it with dc supply using 45W magsafe2 original cable. The current consumption varies from 0.018ma to 350ma with frequent pulses.

I've again checked the mb under microscope and everything seems fine. These are the rail measurements:

PPBUS_G3H:8.6V
PPBUS_S5_HS_COMPUTING_ISNS: 8.6V
PPBUS_S5_HS_OTHER_ISNS: 8.6V
PPDCIN_G3H_ISOL:14.8V
PP3V42G3H:3.44V
PPVRTC_G3H:3.32V
PP5V_S5:5.03V
PP3V3_SUS:3.3V
PP3V3_S5:3.3V

All the above rails are stable.

These rails are pulsing:
PP5V_S4RS3: PULSING BETWEEN 0.0 TO 2.99V
PP5V_S0:PULSING BETWEEN 0.0 TO 0.45V
PP3V3_S4:PULSING BETWEEN 0.0 TO 1.36V
PP3V3_S3: PULSING BETWEEN 0.0 TO 1.75V
PP3V3_SO:PULSING BETWEEN 0.0 TO 1.52V
PP3V3_S4SW_SNS:PULSING BETWEEN 0.0 TO 3.0V

Known good bios flashed with clean me on a new same model chip, Lio board and connector tested fine with another working a1464.

Need help friends.

[mcplslg123]

Re: Macbook A1464 dead

schematic ,boardview attached

[dellxps15]

Re: Macbook A1464 dead

first remove keyboard, trackpad, battery and all other cable. just mainboard and dc-in and see if it power on. fan could start spinning after 1 minute or so.
edit : this is an old model.... so fan spin right after it power on. i have one board like this with 3 beep. reflowed ram chip is the same and i suspect is pch, but its not available new.

[mcplslg123]

Re: Macbook A1464 dead

first remove keyboard, trackpad, battery and all other cable. just mainboard and dc-in and see if it power on. fan could start spinning after 1 minute or so.
edit : this is an old model.... so fan spin right after it power on. i have one board like this with 3 beep. reflowed ram chip is the same and i suspect is pch, but its not available new.

All the readings in my post is with just logic board and dc-in board.Btw, in this model fan spins as soon as you apply power(without battery)-but thats not happening.

[dellxps15]

Re: Macbook A1464 dead

maybe backlight circuit gone bad ? check C7710 , c7711 if are good or shorted.

[piernov]

Re: Macbook A1464 dead

Probably SPI ROM communication issue like bad trace or resistor. As usual check for damage on J6100.
Can also take a look at U1950 to make sure no pins are corroded (pin 8 especially).
Liquid under SMC could cause issues too.

[mcplslg123]

Re: Macbook A1464 dead

@piernov, i agree its all about spi rom comminication. I've checked C6100/6101 and R6125/26/27/28/30/31/32/33/20/21/22/23/14/15/16/17 for value and all are correct. U1950 is clean.No liquid spill is there on this mb. Any further ideas??

[mcplslg123]

Re: Macbook A1464 dead

maybe backlight circuit gone bad ? check C7710 , c7711 if are good or shorted.

I dont think so it has anything to do with backlit circuit but still checked the caps as per your suggestion and both are good.

[piernov]

Re: Macbook A1464 dead

U6101 was already replaced?
You can take a capture of activity of CS# pin with an oscilloscope. Here is an example of what it should look like: https://logi.wiki/index.php?title=EF...ootup_CS_Graph .
Also replacement SPI ROM should have QE bit set to 1. If unsure, take one from the same model donor board. (even with dirty ME it should turn on, just not boot macOS fully)

[mcplslg123]

Re: Macbook A1464 dead

U6101 was not replaced. It was heavily coroded which i cleaned,rebuilt tracks ans soldered back and it worked for a week or so. I didnt had U6101 at that time but i ordered it and is available with me. Will replace it and update the forum. Spi rom was set to QE1 so thats not the issue. CS# pin i observed on scope and the initial pulse varies from 2s to 6s and doesnt look proper.

[mcplslg123]

Re: Macbook A1464 dead

Thanks master piernov for pushing in the right direction. U6101 replaced and got display. The case can be deemed as closed.