820-3115 No image, on USB

iClub

Member
No oxidation, no USB activity, cooler spins. Replaces u7400 and r7402,03, the CPUIMVP_TONA voltage 0.67V , I found too low.
Voltage: PPbus_g3h 12.59V; PP3V42_G3H 3.42v; ALL_SYS_PWRGD 3.3v; PLT_RESET_L 3.3v;PPVCORE_S0_CPU 0.87V.
 
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2informaticos

Administrator
Staff member
Does VCORE drop from 1.15V to 0.87V?
If yes, board should boot.
Are you sure no USB activity?
Try PC3-10600 RAM modules, one at a time on each slot.
Did you try PRAM reset?
 

iClub

Member
There is no activity on USB. I tested a memory in each slot. I will reset the PRAM when I get to the service.
 

2informaticos

Administrator
Staff member
Board doesn't boot with new file?
I just swapped Fsys area from the file you sent.

PCH heats on these boards, as doesn't have any heatsink...
 

iClub

Member
when I test with the multimeter in the CPUIMVP_TONA mesh the mac turns on, strange. Replaces the u7400 and r7403/02, but still with the defect.
 

iClub

Member
When I started to do the analysis it didn't show image and without activity in the USB, it replaces the u7400 and the resistors, I didn't have result. Then, replaces the u6100, the mac showed white screen, and was locked in the PRAM reset sound, after a certain time it did not give more image. I recorded the BIOS file you sent me and used another BIOS chip, but it didn't work.
 

iClub

Member
The mac displays an image, but when I select MacOS, it freezes. And most of the time it doesn't give an image. Vcore 1.12V after a few seconds it drops to 0.87V. It looks like a RAM or CPU defect.
I tested with RAM 10600 and 12800 module.
 

2informaticos

Administrator
Staff member
"Vcore 1.12V after a few seconds it drops to 0.87V"
That is normal behaviour and I explained to you several times!
The drop voltage, means the board is booting.
However board can get stuck after few seconds; have to find a reason for that.
Did you reball SMC?
 
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iClub

Member
I changed the SMC, in the tests the board is with the same defect. In SMC it had a relief in one of the pads, so I replaced it.
 
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