MacBook Pro A1286 - GPU Issue - Fan Spin 2 Seconds - GSM-Forum

simplylcd · 02-02-2021, 13:14

820-2915 MacBook - No screen / no boot / no chime just fans spins for about 2/3 seconds
I have already checked the following core voltages:
ppbus_g3h=12.5v
Dcin = 16v
pp3v42_g3h =3.4v
ppvrtc_g3h= 3.3v
PP5V_S5=5v
PP5V_SUS=5v
PP5V_S3=0v
When I short power on pads , fans spin then shuts down and pp5v_s3=5v for about 2 seconds then shutdown to 0v.
I removed L2406 so I could program the g-mux but the same thing was happening - on , fan spin , off
ppvcore_gpu diode = 0v
ppvcore_gpu = 4.5 ohms
Any tips would be useful.

macbookrepairdu · 02-11-2021, 21:37

Replace the GPU chip
Also, check CPU supply
Change CPU ic and change CPU
Also check near GPU and CPU resistance

02-02-2021, 13:14	#1 (permalink)
simplylcd Junior Member Join Date: Nov 2015 Location: United Kingdom Posts: 6 Member: 2482696 Status: Offline Thanks Meter: 1	MacBook Pro A1286 - GPU Issue - Fan Spin 2 Seconds 820-2915 MacBook - No screen / no boot / no chime just fans spins for about 2/3 seconds I have already checked the following core voltages: ppbus_g3h=12.5v Dcin = 16v pp3v42_g3h =3.4v ppvrtc_g3h= 3.3v PP5V_S5=5v PP5V_SUS=5v PP5V_S3=0v When I short power on pads , fans spin then shuts down and pp5v_s3=5v for about 2 seconds then shutdown to 0v. I removed L2406 so I could program the g-mux but the same thing was happening - on , fan spin , off ppvcore_gpu diode = 0v ppvcore_gpu = 4.5 ohms Any tips would be useful.

02-11-2021, 21:37	#2 (permalink)
macbookrepairdu Junior Member Join Date: Aug 2020 Location: dubai Age: 34 Posts: 2 Member: 2966707 Status: Offline Thanks Meter: 0	Replace the GPU chip Also, check CPU supply Change CPU ic and change CPU Also check near GPU and CPU resistance