820-00967 component identify

[yair37]

L9090 0v 400
And there is now just one light..

 

[yair37]

Q1030 PP12VR11V_G3H_RSNS 12v and PP12v_MAIN 0v and the voltage climb very very slowly

 

[yair37]

I was replaced Q1030 but the same

 

[yair37]

PP12v_MAIN 0v and the voltage climb very very slowly

up to 3v not more then that..

 

[2informaticos]

"L9090 0v 400"
Did you check its continuity?

Check what happens when you've changed U9000; broken trace, bad solders, knocked off component.

 

[yair37]

PP12v_MAIN 0v on Q1030 continue to L9090 and continue to PP12V_S0_CPUCORE_FLT_REG..
from were i get the PP12v_MAIN and PP12v_s0? i do get 12V on PP12VR11V_3GH
i was put few time the U9000 but the same, and no short or missing/broken component...wierd!

 

[yair37]

i dont get 12v like before on (r9003) PP12V_S0_CPUCORE_FLT 12v side 1 so its not from U9000.. should i need to fix the 12v first right?

 

[2informaticos]

PP12V_MAIN comes from PP12V_ACDC power rail (RI010).
Check diode mode to ground at PP12V_MAIN first.

PP12VR11V_3GH comes from PP11V_ACDC.

 

[yair37]

o.k!! i didnt know that the 4 screws on the power supply are important for this!
so now i have again 12v on side 1 of r9003 but i have 0v on side 2 (REG_CPU_VINSNS) 500 on diode mode.
and still just on light...restore not do nothing...just stuck.

 

[yair37]

r9003 is 100k out of the board but its show 2k on the board

 

[2informaticos]

Big value resistor shows lower value measured on board; depending on other components (resistors, chips) connected in same points.

Do not expect 12v after R9003; calculate R9003/4 divider, to find its output voltage.

 

[yair37]

How do I calculate that? And what is the next step?

 

[2informaticos]

Calculated voltage is 0.177V aprox.

What happened on the MLB?
You had two lights, before touching U9000.
Re-check what you did there.

 

[yair37]

i will check again...LED #2 is CORE_VOLTAGES_ON. PP3V3_S0 0V - 180

 

[yair37]

i can find the problem..U9000 look fine..i dont know what to check around, and i prefer to go step by step to see exactly from where is the problem.

 

[yair37]

I can’t *

 

[2informaticos]

Be sure all ZTI0xx points are connected to the power supply.

 

[yair37]

o.k i was put back the "old" u9000 now it pass DFU there is just 2# light, the 3# light is the memory sticks? or something else ?

 

[2informaticos]

Yes, it should light before the GPU LED.
If S0 LED is on, there must be several coils with voltage, including the one for RAM; check that.

 

[yair37]

O.k it was also problem with one of the memory stick..
Now everything work.!
So for other that will fix this shi** few things.
All the 4 power supply screws(silver) must be connected to get 12v on board.
After replace/upgrade something and you see one led on, just do restore with DFU.
1# led is mean that the board is getting voltage.
2# turn on just after restore if you replace something.
3# just when the iMac is on and getting the gpu work.
Hope it will work for other!
And be careful when you take the board off, you can broke some components off
Thanks