Apple 820-2523-B green light, no fan spin

[ktmmotocross]

Hello .
Have this Apple 820-2523-B that have green light on chager , but have no fan spin.

I measure that i have good voltage on PBUS, PP3V42_G3H, PP3V42_G3H, PP3V3_S5, PP1V2R1V05_S5

system takes 0.6W and whe i press powerbutton it goes down to 0.4 and after while back to 0.6W

i even reballed the MCP ic but no change

anybody have idea where to check for fault?

[piernov]

Re: Apple 820-2523-B green light, no fan spin

History? Check all power rails before and after pressing power button.

[ktmmotocross]

Re: Apple 820-2523-B green light, no fan spin

damn. found straight short on GPU resistor withou gpu coil

[piernov]

Re: Apple 820-2523-B green light, no fan spin

Which one, what resistance to ground?

[ktmmotocross]

Re: Apple 820-2523-B green light, no fan spin

R8940 without resistor 0,1ohm on GPU side

[ktmmotocross]

Re: Apple 820-2523-B green light, no fan spin

anybody knows if there can be made DIS to UMA?

[ktmmotocross]

Re: Apple 820-2523-B green light, no fan spin

strange thing is when i inject 1V it take max 1A so it is not short

[piernov]

Re: Apple 820-2523-B green light, no fan spin

Was the GPU reflowed?
It may be possible to bypass GMUX like on 820-2915. In any case you can first remove the GPU inductors or current sense resistors to see if the machine turns on (even with no display/no POST).