820-00138 Fans spins but no boot


Was liquid damaged but cleaned by another repair shop so i can not see any corrosion. I asked the other shop if they could remember or had pictures of the damage but no luck.


When AC connected fans starts to spin then stop then start and slowly goes faster and faster

At the moment where fans stop for 1-2 seconds there is 3.3V on p5 and p6 on U6100 (SPI_MLB_IO0_MOSI and SPI_MLB_CLK) but at the moment the second spin starts these two values go down to some mV.

I dont have board view for this one and bus termination resistors are positioned a bit different than the 00163 board view so i am having trouble measuring all of them. But the ones i can see the traces measure fine.

I tried replacing U6100 temporarily but it did not help so i put the original one back

I tried replacing SMC but same issue

Any ideas?


Yeah this will suck....Could be everything including the so common dead CPU on these. The common checks would be U1900/U1950/U6100 resistors. Inspect board closer for corrosion, it is always visible if you look close enough.