ASRock B650I Lightning WiFi no boot

[Weissnix4711]

Hi all,

I'm having some trouble with an ASRock B650 board, any help would be appreciated. Appears to boot at first, turns PSU on, fan spin, but does not post. no display output, beep codes, or anything.

Tracing signals after power button press,

PSIN and PSOUT work as expected,
SIO asserts PSON and the PSU turns on.
RSMRST# jumps to 1.5V then immediately starts decaying over ~200us.
SLP_S3# and SLP_S4_s5# stay high throughout.

Further power good signals:

ATXPGD, PWROK0 and PWROK1 (labelled O_PWROK1, SIO_PWROK and PWROK_PS in boardview) are high. good.
SYS_PWROK (from CPU) stays low

I don't understand the ACPI power sequence properly, so please any help is appreciated.

Boardview attached.

Thanks,
Thomas

[SMDFlea]

Please post the boardview in a new thread in the Bios & Schematics requests forum https://www.badcaps.net/forum/troubl...matic-requests ,then post a link to it from this topic

[Weissnix4711]

https://www.badcaps.net/forum/troubl...wifi-boardview