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Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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    #81
    Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

    Alright, I suggest visually inspecting it (for corrosion, burnt components, etc.), see how it behaves, and then starting a new thread for it here.

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      #82
      Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

      Let you know when It arrives.

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        #83
        Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

        Originally posted by rccrasher65 View Post
        Let you know when It arrives.
        Should have board on Sat. Excited to get into another component level project.

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          #84
          Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

          Originally posted by rccrasher65 View Post
          Should have board on Sat. Excited to get into another component level project.
          Surprise, board has arrived, I examined board for corrosion or burnt components, non found, board actually looks brand new, better than my original. Will get the meter out and do some measurements.

          Comment


            #85
            Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

            [QUOTE=rccrasher65;880251]Surprise, board has arrived, I examined board for corrosion or burnt components, non found, board actually looks brand new, better than my original. Will get the meter out and do some measurements.
            Last edited by rccrasher65; 02-08-2019, 03:00 PM.

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              #86
              Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

              [QUOTE=rccrasher65;880264]
              Originally posted by rccrasher65 View Post
              Surprise, board has arrived, I examined board for corrosion or burnt components, non found, board actually looks brand new, better than my original. Will get the meter out and do some measurements.
              I did some basic checks on power rails. no 19v and no 3.3v. Dead.This one might be a challenge. That was just a real quick check, will do a better one,and post results.

              Comment


                #87
                Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                I do tend to prefer the ones that are as dead as possible. The further it gets in the power-up sequence before failing, the more effort it is to troubleshoot on average. But, sometimes they surprise you.

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                  #88
                  Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                  [QUOTE=rccrasher65;880414]
                  Originally posted by rccrasher65 View Post
                  I did some basic checks on power rails. no 19v and no 3.3v. Dead.This one might be a challenge. That was just a real quick check, will do a better one,and post results.
                  On connector CN11- pins 1and 2- 19.73V. PQ5- pins 1-3 11.3 mv, gate-10.3mv drain, pins 5-8 19.73V PQ9 1-3 0.7mv, gate- 10.3mv, drain- pins 5-8 8.3 mv. PL12-7.3mv, no 3.3V. all other PL coils are in mv readings.

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                    #89
                    Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                    [QUOTE=rccrasher65;880512]
                    Originally posted by rccrasher65 View Post

                    On connector CN11- pins 1and 2- 19.73V. PQ5- pins 1-3 11.3 mv, gate-10.3mv drain, pins 5-8 19.73V PQ9 1-3 0.7mv, gate- 10.3mv, drain- pins 5-8 8.3 mv. PL12-7.3mv, no 3.3V. all other PL coils are in mv readings.
                    follow the path of 19V rail and check component for short.

                    You will not see 3.3V till you fix 19V.

                    Coils that have short to ground, you can remove and see on what side you get short. Then you attach power supply like in your previous fix and check for hot components.

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                      #90
                      Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                      Alright, so the 19V is not getting past PQ5/PQ9. These are called the "input MOSFETs" or just "input FETs". For a refresher on MOSFETs see my favorite tutorial here.

                      Every MOSFET has a "body diode" due to the way they are constructed. This diode goes between Source and Drain. So, you will notice that MOSFETs are always oriented such that the body diode is blocking the expected direction of current flow in the circuit until the MOSFET is intentionally switched on. Obviously, suing a MOSFET as a switch won't work so well if your switch just leaks current right through due to the direction of the body diode (unless this is intended behavior).

                      So that is why PQ5 exists and is oriented the way it is. But we also don't want power flowing the other way unintentionally (e.g. when it's running on battery power you don't want battery voltage to be on the DC jack pin ). So that is why PQ9 exists.

                      (Side note: Be aware that some boards utilize a "pre-charge" circuit that routes power around the input FETs at a very low current, just to soften the turn-on and to ensure there is no short before it turns on the low-resistance path through the input FETs. This is not one of those boards, however.)

                      They are both turned on simultaneously (gates are connected). And the thing that turns them on on this board is the charger chip PU20. That chip handles switching the input FETs as well as controlling the charging of the battery.

                      The low voltage on the input FET gates tells us that they are not being told to turn on. Either PU20 doesn't want to do so, or it can't do so. Therefore, we need to examine PU20 more closely.

                      Measure voltages on all pins of PU20. Ideally, you should use a needle probe to avoid shorting any pins. You can also attempt to follow the traces and do the measurement at a nearby component, but direct measurements of the pins themselves is best.

                      Comment


                        #91
                        Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                        Originally posted by BlueMidnight View Post
                        Alright, so the 19V is not getting past PQ5/PQ9. These are called the "input MOSFETs" or just "input FETs". For a refresher on MOSFETs see my favorite tutorial here.

                        Every MOSFET has a "body diode" due to the way they are constructed. This diode goes between Source and Drain. So, you will notice that MOSFETs are always oriented such that the body diode is blocking the expected direction of current flow in the circuit until the MOSFET is intentionally switched on. Obviously, suing a MOSFET as a switch won't work so well if your switch just leaks current right through due to the direction of the body diode (unless this is intended behavior).

                        So that is why PQ5 exists and is oriented the way it is. But we also don't want power flowing the other way unintentionally (e.g. when it's running on battery power you don't want battery voltage to be on the DC jack pin ). So that is why PQ9 exists.

                        (Side note: Be aware that some boards utilize a "pre-charge" circuit that routes power around the input FETs at a very low current, just to soften the turn-on and to ensure there is no short before it turns on the low-resistance path through the input FETs. This is not one of those boards, however.)

                        They are both turned on simultaneously (gates are connected). And the thing that turns them on on this board is the charger chip PU20. That chip handles switching the input FETs as well as controlling the charging of the battery.

                        The low voltage on the input FET gates tells us that they are not being told to turn on. Either PU20 doesn't want to do so, or it can't do so. Therefore, we need to examine PU20 more closely.

                        Measure voltages on all pins of PU20. Ideally, you should use a needle probe to avoid shorting any pins. You can also attempt to follow the traces and do the measurement at a nearby component, but direct measurements of the pins themselves is best.
                        Checked board under scope for over an hour, found a lot of PU components, but no PU20. Need some help locating PU20.

                        Comment


                          #92
                          Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                          You can use the boardview file posted earlier in this thread along with OpenBoardView to find out where any component is located.

                          For some things, like this chip, you can also look in the schematic for the part number of the component and then looked for that. PU20 is a BQ24780S, and you'll find that written on the chip. But visual aids are always nice, so I've attached photo #7.
                          Attached Files

                          Comment


                            #93
                            Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                            Originally posted by BlueMidnight View Post
                            You can use the boardview file posted earlier in this thread along with OpenBoardView to find out where any component is located.

                            For some things, like this chip, you can also look in the schematic for the part number of the component and then looked for that. PU20 is a BQ24780S, and you'll find that written on the chip. But visual aids are always nice, so I've attached photo #7.
                            Thank you for that, I passed over that a million times, Its not marked on the board. No matter what I try to use to open that rar file, for the board view, I cannot get it to open. Are the pins on that chip in any special order, or just test each one, and report voltages?

                            Comment


                              #94
                              Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                              The dot on corner of the top of the chip indicates pin 1 (the top-right corner in the photo). The pins are then numbered counter-clockwise around the chip, reaching pin 28 by the time you get to the dotted corner again.

                              You can open the RAR files with 7-Zip.

                              Comment


                                #95
                                Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                                Originally posted by BlueMidnight View Post
                                The dot on corner of the top of the chip indicates pin 1 (the top-right corner in the photo). The pins are then numbered counter-clockwise around the chip, reaching pin 28 by the time you get to the dotted corner again.

                                You can open the RAR files with 7-Zip.
                                pins 1-24 range from 128.8mv-338.7mv pin25- 6.08v 26- 5.07v 27-133.8mv 28-19.7v That was almost impossible, even with needle probes. Pins 1-24 had only mv.

                                Comment


                                  #96
                                  Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                                  It takes a little practice and a very thin probe. You can hold the probe at a relatively shallow angle against the PCB, and rake very slowly and gently across the edges of the tips of the pins the way you might run your nail across the teeth of a comb.

                                  BTW, the pins you wrote as 25 and 26 are almost certainly pins 24 and 25. It's easy to lose count on these.

                                  When you are troubleshooting a more complicated circuit, I recommend writing the voltages right onto the schematic (either in your PDF app or with pen on a printed page). Then, look at each voltage and make sure you understand why it does or does not make sense. It's hard at first, but you should be able to understand more and more as you go along.

                                  For example, we can look at pin 28 (VCC). It's coming from "+VA" (which you already know has 19V), it goes through a diode PD9, can't go backwards through the other diode PD7 (which is there to allow battery power through instead if its voltage is higher than the voltage coming from the DC jack), gets stored in a capacitor PC32 to keep a little stable reservoir of charge right next to the chip, and then goes to pin 28. And "Vcc" means it is a power input for that chip. It makes sense why it would be 19.7 volts.

                                  In fact, like many chips (but not all), we can find a datasheet for PU20 by doing a web search for the part number. It is here.

                                  Pin 24 (REGN) is the output of a 6V regulator inside of PU20, so no problems there. Pin 25 (BTST) makes sense too, but I'll save that explanation for later.

                                  And almost all the pins where you measured near-zero volts make sense... except pin 6 (ACDET). That is also connected to +VA. Now.. it's not going to be 19V, but it should be something. PR24 and PR15 create a voltage divider that lowers the voltage by a specific percentage so the chip can sample it. The resistance of PR15 is roughly 13.9% of the total resistance between ground and +VA (PR15 + PR24), and there are no other resistors to complicate things, so we would expect pin 6 to read roughly 13.9% of whatever +VA is.

                                  So, first thing... check pin 6 again. If it's ~2.7V then we will move on. If it is not, then we will investigate why. Without voltage on ACDET, PU20 will think there is no AC adapter present, and would have no reason to turn on the input FETs.

                                  Comment


                                    #97
                                    Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                                    Originally posted by BlueMidnight View Post
                                    It takes a little practice and a very thin probe. You can hold the probe at a relatively shallow angle against the PCB, and rake very slowly and gently across the edges of the tips of the pins the way you might run your nail across the teeth of a comb.

                                    BTW, the pins you wrote as 25 and 26 are almost certainly pins 24 and 25. It's easy to lose count on these.

                                    When you are troubleshooting a more complicated circuit, I recommend writing the voltages right onto the schematic (either in your PDF app or with pen on a printed page). Then, look at each voltage and make sure you understand why it does or does not make sense. It's hard at first, but you should be able to understand more and more as you go along.

                                    For example, we can look at pin 28 (VCC). It's coming from "+VA" (which you already know has 19V), it goes through a diode PD9, can't go backwards through the other diode PD7 (which is there to allow battery power through instead if its voltage is higher than the voltage coming from the DC jack), gets stored in a capacitor PC32 to keep a little stable reservoir of charge right next to the chip, and then goes to pin 28. And "Vcc" means it is a power input for that chip. It makes sense why it would be 19.7 volts.

                                    In fact, like many chips (but not all), we can find a datasheet for PU20 by doing a web search for the part number. It is here.

                                    Pin 24 (REGN) is the output of a 6V regulator inside of PU20, so no problems there. Pin 25 (BTST) makes sense too, but I'll save that explanation for later.

                                    And almost all the pins where you measured near-zero volts make sense... except pin 6 (ACDET). That is also connected to +VA. Now.. it's not going to be 19V, but it should be something. PR24 and PR15 create a voltage divider that lowers the voltage by a specific percentage so the chip can sample it. The resistance of PR15 is roughly 13.9% of the total resistance between ground and +VA (PR15 + PR24), and there are no other resistors to complicate things, so we would expect pin 6 to read roughly 13.9% of whatever +VA is.

                                    So, first thing... check pin 6 again. If it's ~2.7V then we will move on. If it is not, then we will investigate why. Without voltage on ACDET, PU20 will think there is no AC adapter present, and would have no reason to turn on the input FETs.
                                    Pin 6 does measure 2.60V, I must have missed the reading. I have fine needle probes, but I think I'm going to raid my wife's sewing room for some ulta fine needles, I can solder onto a spare pair of probes.

                                    Still trying to open up those Rar files. I downloaded what you sent me, and still no luck opening them. Its just my dumb ass, I'll figure it out eventually.

                                    Comment


                                      #98
                                      Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                                      @BlueMidnight party again
                                      Just tip from noob.
                                      Also when have boardview file we be able avoid direct measurement to pinout IC

                                      Comment


                                        #99
                                        Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                                        Alright, if there is 2.6V at pin 6, then (according to the datasheet) PU20 has every condition satisfied to turn on the input FETs. Let's investigate a couple of related things:

                                        1. Pin 5 (ACOK) is supposed to go high to communicate the fact that the AC adapter voltage is okay to the rest of the board. Check this pin again just to be sure.

                                        2. Pin 4 (ACDRV) is supposed to rise to 6V above pin 3 (CMSRC) in order to turn on the input FETs. What if something were wrong here? For example, perhaps there is a short between those two pins. That would sure keep pin 4 from having a much different voltage than pin 3.

                                        Measure pin 4 again, just to be sure. Then, with power disconnected, do the diode mode test on PQ5/PQ9. Source to drain, drain to source, and gate to both.

                                        If we don't find anything external that raises a red flag, then PU20 itself may be bad.


                                        Originally posted by on/off View Post
                                        @BlueMidnight party again
                                        Party

                                        Oh but do watch out for that rare occasion when a broken via or solder joint causes the IC pin voltage to be different than it is elsewhere. That will really drive you insane. heh

                                        Comment


                                          Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

                                          Originally posted by BlueMidnight View Post
                                          Alright, if there is 2.6V at pin 6, then (according to the datasheet) PU20 has every condition satisfied to turn on the input FETs. Let's investigate a couple of related things:

                                          1. Pin 5 (ACOK) is supposed to go high to communicate the fact that the AC adapter voltage is okay to the rest of the board. Check this pin again just to be sure.

                                          2. Pin 4 (ACDRV) is supposed to rise to 6V above pin 3 (CMSRC) in order to turn on the input FETs. What if something were wrong here? For example, perhaps there is a short between those two pins. That would sure keep pin 4 from having a much different voltage than pin 3.

                                          Measure pin 4 again, just to be sure. Then, with power disconnected, do the diode mode test on PQ5/PQ9. Source to drain, drain to source, and gate to both.

                                          If we don't find anything external that raises a red flag, then PU20 itself may be bad.




                                          Party

                                          Oh but do watch out for that rare occasion when a broken via or solder joint causes the IC pin voltage to be different than it is elsewhere. That will really drive you insane. heh
                                          OK, pin 4-61.4mv pin 5-176.3mv pin 6-2.64v Diode test on PQ5- red on source, Blk on drain- 0.454v Blk on source , Red on drain-OL OL- gate-source OL-gate -drain. Diode test on PQ9-Red on source, Blk on drain-0.549v Blk on source, Red on drain-OL OL-gate-source OL-gate -drain. These seem to test good.

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