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Asus Rog Strix 3070 - no 1V8

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    #1

    Asus Rog Strix 3070 - no 1V8

    Hi everyone.

    I'm trying to repair my ASUS ROG STRIX 3070 which was broken. I have burnt PU1 and I have CG1425-version schema and boardview. According to the schema, it is a buck converter TPS51396ARJER. I soldered a newly purchased converter, however 1V8 is not generated. I have VIN 12V, SS 3.3V, FB voltage, and correct value resistors for FB, but I do not have an EN signal. I found this signal unconnected by an open contact pad (for the resistor PR10 as per the schematic). I doubt that there was one initially. 3V signal PS_1V8_EN is present. I stuck with this problem and could not find a better schematic. Maybe there was another power unit IC and the schematic is invalid?

    Can anyone suggest to me what would be a possible way to figure this out?


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    #2
    so u have EN after soldered PR10 or not

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      #3
      It seems I found the problem and it is not EN, but the wrong buck converter. The schema I have specifies TPS51396A, however, according to the PCB layout and connections, it was a mysterious SYV728RAC, which I have found on the schematic for ASUS 3060 Ti. I cannot find a datasheet for it and no one sells this IC. Can anyone share the alternative buck converter or datasheet? Or the only way is to salvage this from a donor board?

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        #4
        Click image for larger version Name: image (1) (1) (1).png Views: 0 Size: 242.9 KB ID: 3304702

        The schematic for 1.8V includes two buck converters which can be alternatively placed, but require adding or removing some elements. My board originally had an SYV728RAC which was successfully burned out, and I cannot buy it anywhere, so I decided to try installing a TPS51396A buck converter.

        I followed the schematic and datasheet for the TPS, but it still refuses to produce the required 1.8V despite providing VIN and EN. I tried soldering two TPS chips (to eliminate overheating), but neither of them worked. I even have no VCC, which should be present if the EN pin is high (I have 3.2V on it).

        Can anyone help me identify the possible problem?

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          #5
          no until u post full pin measure. voltages and resistance to gnd

          Comment

            #6
            with disconnected coil PL1:

            Voltages (present):
            VIN = 12.1V
            EN = 3.2V
            PGOOD = 3.2V (comes from outside, if disconnect PR18 then no voltage on PGOOD)
            VCC = 20mV
            FB = 3mV
            MODE = 0.4V

            Resistances to GND:
            BST = 0L
            VIN = 2.7k
            SW = 1.5m
            PGOOD = 90k
            SS = 0L
            EN = 99k
            FB = 34k
            MODE = 39k
            VCC = 105k

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              #7
              vcc dont look good

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