820-00138 Fans spins but no boot

Sykulski

Member
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.

Symptoms:

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?
 

dukefawks

Administrator
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.
 
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