Apple MacBook Air A1466 EMC 2925

[mferna14]

Hi all , I am working on this Logic Board 820-00165-A EMC 2925 (Intel i5 1.6MHz).. No Display what so ever. I re-programmed the EEPROM chip but still no luck. I get all the required voltages. Display/CPU/Memory VCORE voltages are all good. There is absoluetly no liquid spill on the logic board, its clean as ever. LCD Display fuse, I get 8.5Volts when harness cable is connected. Any idea what's going wrong with the Logic board. No chime but fan spin is very normal. I feel CPU gets hot as though its working in the background. Replaced with a known good LCD Screen, no luck. Maybe SMC bad??? Any tips will be greatly appreciated. Thanks

[piernov]

Re: Apple MacBook Air A1466 EMC 2925

No image, no backlight or both? PRAM reset done? Image on external display? History of the device? Activity on USB drive?

[mferna14]

Re: Apple MacBook Air A1466 EMC 2925

I worte that I replaced the LCD Screen, No image or backlight & no chime., It came in as no display & no start chime & no liquid spill anywhere. No activity on any bootable USB. Did a PRAM reset but it did not help. Any more tip will be appreciated.

[piernov]

Re: Apple MacBook Air A1466 EMC 2925

PLT_RESET_L present? Do you have an oscilloscope to check for activity on SPI ROM CS# pin and LPC bus LFRAME#?
Try another EFI if possible (swap the SPI ROM from donor board if you have one).

[mferna14]

Re: Apple MacBook Air A1466 EMC 2925

Ok thanks, I checked PLT_RESET_L & its ZERO volts out there.... no volts at all. What voltage reading should it show on this line???

[piernov]

Re: Apple MacBook Air A1466 EMC 2925

PLT_RESET_L should be 3.3V. Check if it's shorted to ground. And check if PM_PCH_SYS_PWROK, CPU_VCCST_PWRGD and LPC_PWRDWN_L are present.

[mferna14]

Re: Apple MacBook Air A1466 EMC 2925

Thank you very much., I will have it checked first thing in the morning when I am in my workshop.... & do all these signal PM_PCH_SYS_PWROK, CPU_VCCST_PWRGD and LPC_PWRDWN_L should have to be 3.3v????