Xbox Series X mosfet controller questions

[liquidzorch]

Hello. I got in an xbox series x that was taken apart to clean, then reassembled, after that, it powers on then off instantly.

When pressing the on button, I have found that the two ic's that control voltage to the memio, memphy (MP2926) and cpu, gpu (MP2855) DO recieve an EN signal, and probing the pwm outputs (that go to the intellegent mosfets (MP86965)) of both of the ic's go high, but there is no PWMing (probed with oscilloscope).

So the EN pin goes high, the PWM output (all of them) goes high for about half a second, then everything goes low again.

I have inspected the boards both sides with a lense, three times already, there are no missing components, and no missing standby voltages. The power on sequence of the Xbox "ONE" was the memory first, then the NB core, then the APU. This one seems to be all that together, as the same enable line (VREG_1P1_ACTIVE_EN) goes to both the controllers.

What could cause there to be no PWM signals going out to the mosfets? I do get a really low ohm reading on the gpu side (0.1ohm), but even if that was a real short, there should still be some PWM to try to turn it on (at least that's what happend in previous versions), but it just goes high and that's it.

Any advice?

[liquidzorch]

Re: Xbox Series X mosfet controller questions

Here is a snip of the schematic, it's the MEMIO controller. This controller has a datasheet, unlike the gfx controller. And if I understand it correctly, once EN goes high, there should be a PWM out each of the PWM lines, but mine only go high.

[amigo744]

Re: Xbox Series X mosfet controller questions

Hello,

i have also here an xbox series x, that after cleaning and thermal paste replacement goes on and off..
Have you solved the problem ?

[gurj1979]

Re: Xbox Series X mosfet controller questions

I believe those controller chips by MPS must be progtammed. Various laptops use the same controller chip and need to be programmed.
Good luck.