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Dell Inspiron 7506 2-in-1 HELLCAT 19859-1 - No power

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    Dell Inspiron 7506 2-in-1 HELLCAT 19859-1 - No power

    Hi all,

    I've had trouble with the power on this device since I got it. It always shut down with no warning and would often fail to power up. Dell's advice has been to disconnect the power and battery, wait, then reconnect and boot. Letting the battery run down completely also helped. I had them come out at one point and they said they replaced the board. This helped for a while but then it just stopped powering on. At this point it's well out of warranty. I missed the chance to get them to come out again because life. Current situation is it shows zero signs of life with both barrel and USBPD as charger. No LED, no nothing.

    Wanting to fix this (and having only used it for about 2 hours in total since purchase) I decided to open it up and have a look. I have a boardview for the 19860 and schematics for the 19860 and the 19859. I had a look at standby rails. The 3V has something weird. The schematic for both models are identical and have a pair of Schottky diodes acting as an OR gate to take Type C and Barrel input (both tested to work btw). Where the component should be according to the 19860 boardview.... there's nothing. It's not stuffed. More than that, it looks like it's been taken out (see photo). The input pins are at voltage as expected, but of course nothing downstream gets anything. While the battery had charge I don't think it was a problem, but now that it's empty it's a problem I guess. Anyone heard about anything like this?

    Thinking back when the engineer swapped the MB I don't remember the usual grief, it just booted up normally. Did he whip that diode pair out? Surely not. But the pads look like they've had something yanked out for sure. THis laptop has had a LOT of complaints about power issues.


    #2
    Just two things.

    A) This does not look like there was anything soldered ever. The marks we can notice are a result of probing (with a Multimeter for example).

    B) From where do you know that this is PD4402? Explain please.
    FairRepair on YouTube

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      #3
      Sorry, of course. Here's the schematic. And a close-up of +3D3V_VDD_DCIN section from page 44 (this is identical in the schematics for both the 19860 and the 19859). Also enclosed a screen shot of the boardview for the 19860 at the location of the photo. The boardview doesn't have a PD4402. It does have the component PD44C1 (highlighted in screenshot) that has identical connections so AFAICT that's a typo, though I could be wrong. That component is at the position given in the photo I sent.

      Hoping that gives the info you need. Let me know if not and I'll send more.
      Attached Files

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        #4
        I'm curious but not convinced, since there are simple reasons why PD4402 respectively PD44C1 is missing. For example that the device has not the capability to be powered from USB-C or classic barrel charger. Or the designers implemented a different solution. In this case the schematics would simply not match for this particular question.

        What's the voltage at PU44C1, respectively U4302 Pin 1?
        FairRepair on YouTube

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