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    #21
    Re: Lenovo Yoga 910 Charging Problem

    Originally this issue came about due to liquid damage to the DC in board (LIO) which had corrosion that had eaten away some of the trace on the DC in ribbon. A new DC In board and ribbon are installed and they both look clean and appear to have no issues themselves. As far as the power adapter-- I did try with a generic USB C laptop adapter with the same results. Unfortunately I don't have another Lenovo with USB C power to be able to check results with Lenovo adapter but it seems likely that the problem lies elsewhere.

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      #22
      Re: Lenovo Yoga 910 Charging Problem

      Originally posted by BlueMidnight View Post
      Ah okay, so it's an Intersil ISL9237HRZ. And the datasheet confirms a suspicion I had about PQ19 and PQ20. They can be used to boost voltage when the input voltage is lower than required. Anyway.. back to your issue..

      You don't want to inject voltage anywhere... much less on the gate pin of one of the FETs. You have no short to ground. You are measuring positive voltage everywhere (even though the readings change from moment to moment). What you do want to do is measure voltage on all pins of PU4. Hopefully this will tell us whether PU4 is acting up, or if it's one of the FETs, etc. This may be made more difficult due to the readings jumping around, however.

      Also, have you tried a different AC adapter or tried this adapter on another notebook? Because that can also be the culprit.
      here are the readings.

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        #23
        Re: Lenovo Yoga 910 Charging Problem

        There are a few strange things about those readings:

        - The AC adapter is outputting 5V instead of 20V. Negotiation of the power up to 20V is handled by a chip other than PU4. Unfortunately, I have no idea which one or when this board is designed to ask for more power. Perhaps when ACOK gets asserted. Which brings me to...

        - ACOK (pin 24) = 0V. So PU4 is saying that it has not detected proper AC adapter input voltage. Proper voltage is defined as greater than 3.8V AC adapter voltage, and greater than 0.8V on ACIN (pin 19). ACOK is supposed to be asserted after ASGATE goes to 0V, but ACOK is remaining at 0V for some reason

        - ACIN is 4.95V. This is strange because you measured the input as 5.08V. ACIN should be a fraction of that because it is on a resistor divider. In fact, if it truly is 4.95V when the input is 5.08V, then at 20V ACIN would be over 19V and fry the chip.

        - The voltage on VBAT (pin 31) and BATGONE (pin 25) indicate that a battery was connected when you took the readings. But a battery voltage of 4.15V would be a totally dead battery (just over 2V per cell).


        Those are the biggest of the things I see so far. It might just be because the readings are jumping around though. So the first thing to do is to double check the readings on the pins I mentioned. If they remain the same, then that will give us a direction to go.

        I copied your readings onto the reference design in the ISL9237 datasheet to do my analysis, so I've gone ahead and attached that page here. The design of the actual board should be quite similar to the reference design.
        Attached Files

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          #24
          Re: Lenovo Yoga 910 Charging Problem

          Hooking up one of these USB C power meters I get the following readings which are consistent with the readings I got off the Intersil chip.


          When I try the universal USB C charger I can't get any reading of the power meter, it just loops.

          Maybe it is just a defective charger? And the system is not compatible with this particular generic USB C power adapter?

          BTW, the measurements for the Intersil chip were done with only the power adapter connected, no battery. I double check the readings when I get a chance.
          Last edited by mgrharry; 06-26-2018, 06:49 PM.

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            #25
            Re: Lenovo Yoga 910 Charging Problem

            It's really hard to explain all the weird readings you're getting with just a bad charger. It's a good idea to at least start by assuming there is just a single bad component. And right now the leading possibility for a single component that could cause all the strange readings is the Intersil chip itself. But that assumes that the readings are accurate. So we'll know after you get a chance to measure them again.

            If the readings remain the same, then the simplest explanation is that PU4 has internal shorts that are sending the supply voltage out to pins where it doesn't belong (e.g. the VBAT and ACIN pins). Of course, having multiple bad components isn't impossible, but that's a bit less likely.

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              #26
              Re: Lenovo Yoga 910 Charging Problem

              Sadly I ran out of time on this repair and the customer decided to just purchase a new laptop. A few last notes: when I retested with the battery connected the power adapter did output 19.5v, 5v was only with no battery connected.

              Thanks for all your help. I suspect given enough time it would have been solvable...

              Comment


                #27
                Re: Lenovo Yoga 910 Charging Problem

                Ah well, you can't win them all I suppose. You're welcome

                Comment


                  #28
                  Re: Lenovo Yoga 910 Charging Problem

                  Originally posted by mgrharry View Post
                  Sadly I ran out of time on this repair and the customer decided to just purchase a new laptop. A few last notes: when I retested with the battery connected the power adapter did output 19.5v, 5v was only with no battery connected.

                  Thanks for all your help. I suspect given enough time it would have been solvable...
                  If your seriouse about handling customer repaires without minimum online help effort i suggest you invest in getting flir thermal camera.

                  With these you can fix shorts and other problems instantly.
                  Your working hours will be cut and you can get it repaired fast. You will find and locate problematic components soon as you even plug the standard charger.

                  Bite the bullet get one.

                  Comment


                    #29
                    Re: Lenovo Yoga 910 Charging Problem

                    Stevie2001, No offence meant but it seems you rely too much on repair tools like thermal camera and dc power supply etc etc. Agreed, tools are important but tools alone cant fix anything-its your brain and experience which matters most. tools are just to help you but .......

                    Comment


                      #30
                      Re: Lenovo Yoga 910 Charging Problem

                      Originally posted by mcplslg123 View Post
                      Stevie2001, No offence meant but it seems you rely too much on repair tools like thermal camera and dc power supply etc etc. Agreed, tools are important but tools alone cant fix anything-its your brain and experience which matters most. tools are just to help you but .......
                      Edited 1 reader read it thats enough
                      Last edited by Stevie2001; 06-30-2018, 09:04 AM.

                      Comment


                        #31
                        Re: Lenovo Yoga 910 Charging Problem

                        I`ll get the popcorn
                        All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                        Comment


                          #32
                          Re: Lenovo Yoga 910 Charging Problem

                          Originally posted by Stevie2001 View Post
                          Edited 1 reader read it thats enough
                          I have read your answer and think that your point of view to repair a motherboard is too strong, which I would say that you think your point of view is the best to fix a motherboard. Depending on the time and money that the technician has to devote to the repair of a motherboard, it depends on the state of the problem that the technician must repair in a satisfactory time for the customer. If you have all the necessary tools to perform a repair, it will not take time to find the problem, but you must know how a motherboard works with all the components. Without this knowledge, the tools will not help you at all.

                          Comment


                            #33
                            Re: Lenovo Yoga 910 Charging Problem

                            Originally posted by JaroTech View Post
                            I have read your answer and think that your point of view to repair a motherboard is too strong, which I would say that you think your point of view is the best to fix a motherboard. Depending on the time and money that the technician has to devote to the repair of a motherboard, it depends on the state of the problem that the technician must repair in a satisfactory time for the customer. If you have all the necessary tools to perform a repair, it will not take time to find the problem, but you must know how a motherboard works with all the components. Without this knowledge, the tools will not help you at all.
                            Like i said you have experience using a hammer but now that the drill has come out technology makes it easy.
                            Last edited by Stevie2001; 06-30-2018, 03:15 PM.

                            Comment


                              #34
                              Re: Lenovo Yoga 910 Charging Problem

                              For anyone having this problem: Thanks to the help of BlueMidnight in pointing me in the right direction I have isolated and repaired this condiiton on my 910. To date I have seen many others with the same or similar issues with this model with no public account of a successful repair (until now) and it's still a very awesome and sought after unit so it needs to be addressed! He said look to the resistors and mosfets related to the charging/power system first, then the Intersil 9227HRZ controller chip last. The 7 fets involved are all manufactured by Alpha & Omenga semiconductor co. There are 3 AON7405's (PQ-8, PQ-10, and PQ-11), as well as 4 AON7506's (PQ-15, PQ-16, PQ-19, and PQ-20). Methods of testing mosfets can be found here: https://www.google.com/search?q=how+...firefox-b-1-ab Upon testing, PQ-19 was found to have a short between source and gate terminals so was replaced and problem solved! While it may not be the same exact issue in all cases, what is clear is that this model has been well known for having this problem and in most cases it's similar or the same symptom-wise which makes it much more likely to be the exact same failure! Well, hope this info helps some out there


                              battery only:
                              PR53: 1.4v
                              PR57: .2v
                              PF2001: .05v

                              battery + AC:
                              PR53: jumps between 2.3-4v
                              PR57: 4.5v
                              PF2001: 5v

                              Ac only:
                              PR53: 3-4v
                              PR57: 4.5v
                              PF2001: 3.3v


                              On Mosfets: (these tests are done with the cord plugged in and no battery connected, careful to not touch the wrong thing and short the board.)

                              Test 1:
                              Negative to source, positive to drain: should be no voltage in off mode.

                              Test 2:
                              Negative to source, positive to gate momentarily then back to drain: should be voltage.

                              Test 3:
                              Touch finger between gate and source and it should turn off

                              Test 4:
                              Make curcuit with potentiometer and 1k resistor and 10v power supply (10ma max) amp meter in series with drain


                              Alpha & Omenga semiconductor mosfet tests.

                              AON7405......:
                              PQ-8: Test 1: 1.6V both sources Test 2: source 1: 1.6v source 2: 1.6v Test 3: 1.6v out gate, Stayed on
                              PQ-10: .5 both sources Test 2: source 1: .5v source 2: .5v Test 3: 1.6v out gate, Stayed on
                              PQ-11 Source 1: .5v, source 2: 0.0v source 1: .5v source 2: .5v Test 3: 1.6v out gate, Stayed on

                              AON7506....:
                              PQ-15: Test 1: 0.0v Test 2: .9v coming out gate, when gate charged outputs to drain for 1/2 second then nothing Test 3: same as test 2
                              PQ-16: Test 1: 0.0v Test 2: voltage out of the gate always, out the drain split second after charge Test 3: same as test 2
                              PQ-19: Test 1: 0.0v Test 2: same as PQ-16 Test 3: Short between source and gate!!!! [replaced with one off a parts board, SUCCESS!!!!]
                              PQ-20: Test 1: 0.0v Test 2: same as PQ-15 Test 3: same as test 2


                              Originally posted by mgrharry View Post
                              Working on a Lenovo Yoga 910-13IKB, model name 80VF. This unit had liquid damage to the USB C DC in board and ribbon that was preventing it from charging properly when the adapter was plugged in. The unit would sometimes not detect the charger at all, other times it would rapidly cycle from charging to not charging (about every 1-2 seconds) when the adapter was plugged in. There was some corrosion evident the DC in board and ribbon so I replaced them both with a new unit however the same symptoms still persist in the form of rapid cycling between charging / not charging. Clearly there is some component damaged on the motherboard itself however there is no visible corrosion or damage to the motherboard itself.

                              I have a hot air station and microscope so if I can locate the defective component I can probably replace it but I can't locate any schematics for this board and other than haphazard application of freeze spray in the general vicinity of where the ribbon for the DC in board connects, I'm not sure where to start.

                              You can view photos of the board below.

                              Any tips would be greatly appreciated.

                              Comment


                                #35
                                Re: Lenovo Yoga 910 Charging Problem

                                BlueMidnight! I have a Lenovo yoga 910 with some kind of board problem. Hoping the shop tomorrow says it's a power board and not the motherboard like the first shop said. Do you do repairs????

                                Comment


                                  #36
                                  Re: Lenovo Yoga 910 Charging Problem

                                  Thanks everyone for all this information, I am trying to learn and fix a 910 too.
                                  The ISL9237 on mine seems fried and I think I can learn a lot from the info posted here.
                                  I do have a question that the original poster had and I did not see answered : where could one insert 19v (with a switching DC power supply) to see if the board will work?
                                  thank you

                                  Comment


                                    #37
                                    Re: Lenovo Yoga 910 Charging Problem

                                    can anyone add the schematic that has the PQ16 as such in the pdf? mine has U101 there.... Thanks for the explanation BlueMidnight an SSonicComputers.
                                    I tried to replace the ISL9237 which was quite hard . My sorrows continue here:
                                    https://www.badcaps.net/forum/showthread.php?t=86099
                                    join the fun if interested .

                                    Comment


                                      #38
                                      Re: Lenovo Yoga 910 Charging Problem

                                      Hi!

                                      Bump - anybody solved issue with 5v only and no charging?
                                      I replaced pu10 (was burned) pq 10-11, 15,16, 19,20, 8 (only pq16 was burned), measured all resistors nearby, checked caps - still nothing.

                                      Latop turns on only on battery, not on usbc, and no charging...
                                      No VIN voltage, on PQ10-11 only 5v

                                      Help!

                                      Comment


                                        #39
                                        Re: Lenovo Yoga 910 Charging Problem

                                        What are the details of the type c power adapter?

                                        Is it the recommended one for this unit?

                                        Adapter confirmed to be working and able to supply 20v?

                                        If you are stuck at 5v then the power delivery negotiations over the type C connector pins CC1 and CC2 is not working. Fault can be a bad connector; bad adapter or bad communication between the PD sink and PD source.

                                        Remove all power. No battery. Meter in diode mode.

                                        Red meter lead, yes red to ground. Black meter lead to CC1 in the schematics. What is the measurement?

                                        Repeat for CC2 pin. We are checking to see if the communication interface is damaged or not.

                                        Comment


                                          #40
                                          Re: Lenovo Yoga 910 Charging Problem

                                          Hi guys

                                          Lenovo Yoga 910-131KB. Power rail. Can't find datasheet about this probably schottky barrier diodes. Could be for around 25V. Any replacement ideas with DFN1006 standart surface size?
                                          Attached Files
                                          Last edited by sancho76; 11-20-2022, 06:44 AM.

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