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Asus Prime x299 Deluxe - no VCCIO VCCSA voltages

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    Asus Prime x299 Deluxe - no VCCIO VCCSA voltages

    Motherboard after starting show Q code 00.
    No shorts on any rail ( at last I can't finde any)
    All voltage are correct on SIO - 3.3V, PCH power 1V , DDR 1.2V, SPI 8 leg 3.3V
    Nothing get hot, PSU starting, all lights came ON....
    One thing i can see incorrect is no VCCIO and VCCSA voltages and no main power on CPU.
    After deep looking I found dead Synchronous Buck converter CSD97374Q4M that is powering VCCIO for CPU but after replacing it nothing changed. Voltages on it are correct....
    This buck converter is PWM'ed by Asus DigiVRM ASP1405I-62T. Can't finde any datasheet for it but I read its a clone of IR35201 and they look similar.
    Checking that datasheet DigiVRM have all voltages, 3.3V VCC, 1.8V internal, 3.3V Enable, SCL and SDA 3.3V, PWM line is pulled high to 1.6V from 5V main connector.

    Any tought what can I check?
    Is this DigiVRM externally started by PCH ( PCH partialy dead )?
    Any way to check if DigiVRM is OK?
    My last idea is to sniff I2C communication to see if anything is going between DigiVRM and PCH.
    Or maybe something else I haven't thought of???
    Thx for any help.

    #2
    Did you scope the PWM input of the buck controller yet? or at least measured frequency and duty cycle?

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      #3
      There's no PWM on buck controller.
      I must look closer to this Digi VRM chip and try to figure why it don't start to PWM buck controller....
      I think ther is no easy way to replace that chip..
      Last edited by lol999; 01-23-2024, 01:48 PM.

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        #4
        So, there is no way to bypass the PWM signal from DigiVRM and inject your own into the buck controller?

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