Good afternoon for everyone :)

I haven't got idea what is broken so I decided to ask you about help.
I have problem with no power on memory controller. I have took controller coil off and I made tests.

The photo illustrates my reflections.
I think that the RT8105 is broken but I would like to be sure and that is why I need your help. I want to know which direction power is going.

But first of all.
Resistance under coil is 0ohm or 288k ohm.

About voltages
RT8105: 1. Boot = 12V, 2. UGate 0V, 3. GND 0V, 4. LGate 0V, 5. VCC 12V, 6. FB 0B, 7. OPS 1,55V 8. 0V

My considerations lead to UGate is connected with GATE 7030AL (MOS), and LGate is connected with GATE OF 5030AL. Moreover source from 7030 is conected with Drains of 5030.

However I am not sure which value schould be and where.
So the voltage on the UGATE and LGATE should be more than 0V?
Which is the direction from RT8105 to mosfets or maybe from mosfet to RT8105?

In my second test I connect power supply with 1,5V and 4A to coil where was 0 ohm but I didn't find anything. However I think that it is not surprise for you.
Is it short or not?
Should I search in another place on the pcb?

At the end I would like to add that I checked all fuses.
What's more on the picture I mark it that only 7030 have 12V on the drain, where source and gate are 0V. On the 5030 everywhere is 0.

1) check fuses
2) if on the memory side ~ 0 ohm, then gpu is dead

может память сдохла?

maybe memory dead?
---------- Добавлено спустя 8 минут 23 секунды: ----------
how much current was be?
how much current?
---------- Добавлено спустя 3 минуты 33 секунды: ----------
source 5030 at the ground, 0 it is normal
---------- Добавлено спустя 1 минуту 13 секунд: ----------
for good understanding how RT8105 works, see datasheet

Im not sure is it memory site or not. However I have tested it one more time I give 1,5V and 5A. Te maximum voltage was about 1V and 5A. I have used pirometer to check GPU temperature and there was about 1 celcius degree more. That is why I decided to take off gpu and the short has gone. I have yet 15 pcs 5870, so I will try to replace the gpu.

I was very surprised when I took gpu off because almost all of balls was almost that same like after putting new balls. I think that gpu was wrong soldered or something like that.
I will tell more If I place another gpu.

if on the memory side ~ 0 ohm, then gpu is dead

Quaint
а память в таком случае не может быть дохлой?

Hi, After I had taken GPU off I checked voltages and I was very suprised because now I have about 6-7V on memory controller. It is too much. Could you tell me what can I do now or where I schould looking for?

i think upper mosfet is dead(short circuit)

check all memory mosfet