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    Spectre x360 - no power

    I am trying to fix spectre x360 13. Laptop is exactly same as in https://www.badcaps.net/forum/showthread.php?t=82397 (same motherboard)

    Something like ant shorted one cap on 19v around charging controller. I replaced the cap from donerboard (but it may be just removed since it's back filter).

    The board is still dead: no power, lights. I didn't find any other shorts on the board, checked all caps.

    I tracked down that 19v is reaching BQ24715 and mosfets close by . I checked voltages of BQ24715 using values from above thread. Everything looks good. AD_ID is 0.47v

    I see that +3V and +3VPCU are missing. Of course +5v is off as well.

    +VIN is 0.87v which is I am not sure is proper value but I don't have working motherboard to compare.

    So I am stuck at this point. Any help or advise how to troubleshoot further ?

    #2
    Re: Spectre x360 - no power

    Do you have Voltage on PR91?
    Last edited by Sephir0th; 01-17-2021, 02:22 PM.
    FairRepair on YouTube

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      #3
      Re: Spectre x360 - no power

      Originally posted by Sephir0th View Post
      Do you have Voltage on PR91?
      Yes. 19v. The shorted cap was exactly there.

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        #4
        Re: Spectre x360 - no power

        You have a Big BGA Buck Converter. (Never Seen Something Like this before... ) However, the First Rail which has to come Up is +3VPCU.

        Check PL10 for Short to ground. If it isn't short, Check PQ14 and PQ18 beetween D - S, G - S and G - D in lowest Ohms Mode and Tell the values.

        Edit: don't forget to Remove Power, when Measuring.
        Last edited by Sephir0th; 01-17-2021, 03:41 PM.
        FairRepair on YouTube

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          #5
          Re: Spectre x360 - no power

          Originally posted by Sephir0th View Post
          You have a Big BGA Buck Converter. (Never Seen Something Like this before... ) However, the First Rail which has to come Up is +3VPCU.

          Check PL10 for Short to ground. If it isn't short, Check PQ14 and PQ18 beetween D - S, G - S and G - D in lowest Ohms Mode and Tell the values.

          Edit: don't forget to Remove Power, when Measuring.
          No short PL10. PQ14 & PQ18 shows OL between D-S, G-S, G-D. Multimeter lowest is 400om

          I still suspect +VIN ...It is only 0.87v. It seems to very low, right?

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            #6
            Re: Spectre x360 - no power

            Just overlooked the NVDC Design. So yes, You need +VIN for working Power Rails. Do the Same measurement on PQ6, PQ7 & PQ28 Like for the Mosfets before. If you find nothing Special, Check also for Gate Voltage on First both Mosfets. No short on PL6?

            You Said everything seems okay on PU1, but Just to be Sure. What are The Voltages on PIN 3, 5, 6, 16 and 20?

            Is battery plugged in or Out while your measurements?
            Last edited by Sephir0th; 01-18-2021, 12:53 AM.
            FairRepair on YouTube

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              #7
              Re: Spectre x360 - no power

              Originally posted by Sephir0th View Post
              Just overlooked the NVDC Design. So yes, You need +VIN for working Power Rails. Do the Same measurement on PQ6, PQ7 & PQ28 Like for the Mosfets before. If you find nothing Special, Check also for Gate Voltage on First both Mosfets. No short on PL6?

              You Said everything seems okay on PU1, but Just to be Sure. What are The Voltages on PIN 3, 5, 6, 16 and 20?

              Is battery plugged in or Out while your measurements?
              The battery is unplugged when I measure voltage.

              I will check PU1 and rest tomorrow and update the thread. I don't have time to work on the board today.

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                #8
                Re: Spectre x360 - no power

                Originally posted by Sephir0th View Post
                Just overlooked the NVDC Design. So yes, You need +VIN for working Power Rails. Do the Same measurement on PQ6, PQ7 & PQ28 Like for the Mosfets before. If you find nothing Special, Check also for Gate Voltage on First both Mosfets. No short on PL6?

                You Said everything seems okay on PU1, but Just to be Sure. What are The Voltages on PIN 3, 5, 6, 16 and 20?

                Is battery plugged in or Out while your measurements?
                No short on PL6. PQ6, PQ7 & PQ28 are OL between legs (d,s,g)
                PU1
                3 - 17.8v
                5 - 3.37v
                6 - 2.76v
                16 - 6.08v
                20 - 18.9v

                I suspect “hot” short (when voltage applied) on +VIN line. But I am not sure since +VIN is on PU1 (leg 19) and it has same voltage as from another thread. Any ideas ?

                Thanks for helping me.
                Last edited by kostik78; 01-19-2021, 08:34 PM.

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                  #9
                  Re: Spectre x360 - no power

                  Well... I decided to triple check 19v rail again and ... of course PQ8 is shorted (S-D). Not sure how I missed it multiple times. I believe I did checked
                  I don’t have it right now to replace and test. Same mosfet is shorted as well on my donerboard. So I guess I need to buy it. I will update the thread once I do it.
                  Last edited by kostik78; 01-20-2021, 12:49 AM.

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                    #10
                    Re: Spectre x360 - no power

                    Oh...well. I replaced PQ8 and the motherboard came to life. I did a testing and everything was working fine (loosely installed in case with the screen). Touch, keyboard and etc.

                    After I assembled and during the second testing, I shorted accidentally something around V10(1.2V capacitors). I know I know My bad.

                    So now I have non working board again but in different way.

                    If I connect powercharger 19V, VIN, 3VPCU, 5VS5 are good. Also I see V9(1.05VS5) which I am not sure right or wrong. Even the battery is charging.

                    But once I press power button, 3VPCU, 5VS5 and 1.05VS5 go off (ac light as well).
                    Also PQ13, PQ26, PQ4, PQ2 are showing 1.6 Om between G-S and it doesn’t look like the mosfet itself. Initially I thought they were shorted. But I removed one of them and 1.6Om is there, after pressing power button and disconnecting powercharger.

                    Is this board doomed now ? I am still ready to continue but I need a help. I never tried to fix a motherboard before.

                    Any advices ? Thank you.
                    Last edited by kostik78; 01-21-2021, 11:20 PM.

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                      #11
                      Re: Spectre x360 - no power

                      This is Not good. Which mosfet did you removed? And are you Sure with PQ4? Because if this one is shorted, you can't have 19V (VIN) on Main Power Rail. Double-check Please.

                      And also Check PL5 (Low Resistance can be normal Here), PL12 and PL15 to ground. Tell the exact value of PL5. If PL12 and/or PL15 are Reading Low OHMs (the 1.6Ohms, you Had measured) Remove them and Check on which Side is the short, but i guess now PU4 is gone... However, do the Checks to be Sure.
                      Last edited by Sephir0th; 01-22-2021, 01:16 PM.
                      FairRepair on YouTube

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                        #12
                        Re: Spectre x360 - no powero

                        Originally posted by Sephir0th View Post
                        This is Not good. Which mosfet did you removed? And are you Sure with PQ4? Because if this one is shorted, you can't have 19V (VIN) on Main Power Rail. Double-check Please.

                        And also Check PL5 (Low Resistance can be normal Here), PL12 and PL15 to ground. Tell the exact value of PL5. If PL12 and/or PL15 are Reading Low OHMs (the 1.6Ohms, you Had measured) Remove them and Check on which Side is the short, but i guess now PU4 is gone... However, do the Checks to be Sure.
                        PQ4 is VCC_CORE and I don’t think it will affect VIN. I think your point is true for PQ6.

                        I removed PQ4 and PQ2. The low resistance between G-S on these mosfets (and others I specified above) exists only after an attempt to start the board after disconnecting the power-charger. And it lasts for a few minutes (like something keeps a charge that slowly goes away)

                        I don’t see any obvious shorts on “cold” board (except the case I described above). Only one strange thing is 400Om resistance between S-D on PQ24 (even with removed mofset) which doesn’t exist on the doner-board. I am sure that the doner-board should be fine there. It is burned out on main rail beyond repairability (damage on a few layers deep). Also I recall testing this mosfet before the accident.

                        I am thinking about injecting 1v into V9 & V10 and see what is heating up. It has to be short, otherwise I don’t see how 3VCPU&5VS5 would go down after attempting to boot the board.

                        And I am also suspecting PU4 and I didn’t replace it yet because I don’t have templates and balls to reball PU4 from the doner-board.

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                          #13
                          Re: Spectre x360 - no powero

                          Originally posted by kostik78 View Post
                          PQ4 is VCC_CORE and I don't think it will affect VIN. I think your point is true for PQ6.

                          I removed PQ4 and PQ2. The low resistance between G-S on these mosfets (and others I specified above) exists only after an attempt to start the board after disconnecting the power-charger. And it lasts for a few minutes (like something keeps a charge that slowly goes away)

                          I don't see any obvious shorts on “cold” board (except the case I described above). Only one strange thing is 400Om resistance between S-D on PQ24 (even with removed mofset) which doesn't exist on the doner-board. I am sure that the doner-board should be fine there. It is burned out on main rail beyond repairability (damage on a few layers deep). Also I recall testing this mosfet before the accident.

                          I am thinking about injecting 1v into V9 & V10 and see what is heating up. It has to be short, otherwise I don't see how 3VCPU&5VS5 would go down after attempting to boot the board.

                          And I am also suspecting PU4 and I didn't replace it yet because I don't have templates and balls to reball PU4 from the doner-board.
                          To say it exactly, PQ4 is the High-Side Mosfet of the VCORE Power Supply and is feeded from VIN on Source and has VCORE Voltage on Drain. So if you have Only 1.6Ohms beetween S and G, that means your VIN is (partially) shorted to ground (or to VCORE Rail) And this is the reason why i wanted to Double Check this.

                          But yes, i did a mistake. Of course, You don't have 19V on Main Rail (VIN), but a lower voltage (again forgot about NVDC).

                          So let us exclude VCORE for now, because you confirmed, it isn't short. The 400Ohms on PQ24 can be normal, but Tell me the Resistance of the Donor Board. And Tell me too, If there are differences at OHMs Readings on VIN and PL15 (i already asked you before to measure it). Please Share the exact values of the Readings on both Boards.
                          Last edited by Sephir0th; 01-22-2021, 04:05 PM.
                          FairRepair on YouTube

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                            #14
                            Re: Spectre x360 - no powero

                            Originally posted by Sephir0th View Post
                            To say it exactly, PQ4 is the High-Side Mosfet of the VCORE Power Supply and is feeded from VIN on Source and has VCORE Voltage on Drain. So if you have Only 1.6Ohms beetween S and G, that means your VIN is (partially) shorted to ground (or to VCORE Rail) And this is the reason why i wanted to Double Check this.

                            But yes, i did a mistake. Of course, You don't have 19V on Main Rail (VIN), but a lower voltage (again forgot about NVDC).

                            So let us exclude VCORE for now, because you confirmed, it isn't short. The 400Ohms on PQ24 can be normal, but Tell me the Resistance of the Donor Board. And Tell me too, If there are differences at OHMs Readings on VIN and PL15 (i already asked you before to measure it). Please Share the exact values of the Readings on both Boards.
                            PL5:
                            Donerboard - 71 Om (older cpu)
                            The board - 50 Om

                            PL15:
                            Donerboard - 500 Om(red probe on ground), 1.3KOm(black on ground)
                            The board - 400 Om(red), 1.1KOm(black)

                            PL12:
                            Donerboard - 500 Om(red), OL(black)
                            The board - 500 Om(red), OL(black)

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                              #15
                              Re: Spectre x360 - no power

                              Investigate a bit more. When I press power button I see voltage jump on 3V (PQ15), so looks like It tries to enable. So something should be shorted and the protection kicks in. Not sure what to do next - inject 3V and see what starts heating up ?
                              Last edited by kostik78; 01-23-2021, 12:14 AM.

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                                #16
                                Re: Spectre x360 - no power

                                This is weird. Maybe the differences are meaningless, But i Don't know for Sure. Injecting Power won't Help, because i don't See a straight short to ground Here. So we have to Follow the Power sequence. According to the Power flow Chart on Page 32 of the Schematics. Which is the First Signal which is Missing?
                                Last edited by Sephir0th; 01-23-2021, 04:40 AM.
                                FairRepair on YouTube

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                                  #17
                                  Re: Spectre x360 - no power

                                  Originally posted by Sephir0th View Post
                                  This is weird. Maybe the differences are meaningless, But i Don't know for Sure. Injecting Power won't Help, because i don't See a straight short to ground Here. So we have to Follow the Power sequence. According to the Power flow Chart on Page 32 of the Schematics. Which is the First Signal which is Missing?
                                  I think PU4 done. Now the board even doesn’t have 3VCPU and 5VS5 that were working yesterday (even the battery was charging) I will buy a new one on eBay and try to replace it. Desodelirng,rebaling from the donerboard are too many steps to overheat the chip. I will update the thread after I replace PU4.

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                                    #18
                                    Re: Spectre x360 - no power

                                    While waiting PU4 (BGA from China) I got two more same motherboards to fix with no-power issue and one for x360 with usb-c. Decided to share what I found - may be it will be useful for someone.

                                    Board #2 - short on VA caused by EC34. The component looked visually fine but was shorted. After replacing the board works fine.

                                    Board #3 - no power and no obvious short, DC-IN was missing on PQ8. Someone was there with crud tools and replaced PQ8 with another type of mosfet (I even couldn’t read the numbers but it was bigger) and tried to do something with PU1 (a lot of heavy flux there). I replaced PQ8 with proper mofset and PU1 since it was looking strange. VIN and V9(1.05) came online. 3VCPU is there as well but it is quite strange - PQ18 has 20V on leg 4. 5VS5 is missing. But comparing measurements with Board #2 on these lines and around PU4, I came to conclusion that PU4 is dead there as well. So now I have 2 boards with suspected PU4.

                                    Board #4 (dax31mb1aa0 rev.a with usb-c) - Shorted one of tps65982 and both diodes (D36 & D43 - vbus to ground). I have the controllers but I don’t have the diodes. it took for a while to find what type of diode is used there (didn’t have the schematics). I found the diode type on Texas Instruments forum. I ordered them. Funny fact is that by googling the diode and tps65982 I found the board schematics for this model of spectre x360 on another website.
                                    Last edited by kostik78; 02-03-2021, 12:40 AM.

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