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Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

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    #41
    Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

    I have attached a diagram that I modified from a previous version schematic that I believe represents the circuit of interest for this issue.
    Attached Files

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      #42
      Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

      Installed new L6562D which appears not to have been the issue. The waveform at the gate drive to the MOSFETS attached.
      Attached Files

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        #43
        Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

        Attached are the waveforms at the other pins.







        Attached Files

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          #44
          Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

          L6562 Internal diagram

          Attached Files

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            #45
            Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

            If picture 3 is pin 8 you have a problem.

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              #46
              Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

              Originally posted by R_J View Post
              If picture 3 is pin 8 you have a problem.
              Hover over the picture and the description tells which pin it is. Pin 8 is not shown. It is a very clean 15VDC.

              I don't think the Gate drive is going high enough to turn the MOSFETs on. I'm thinking the other inputs are causing the gate drive to shut down. Need to study this part a little more to see exactly how the OVP works.

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                #47
                Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                Attached Files
                Last edited by bznhvx; 04-01-2020, 05:45 AM.

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                  #48
                  Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                  Is this the gate drive out of pin 7? it looks like it should be ok, but is it getting to the mosfet gates?

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                    #49
                    Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                    The waveform shown is at the gate of the MOSFETS.

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                      #50
                      Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                      That's around 7 volts peak, correct? that should turn on the fets, there are 6 resistors (or are they jumper wires?) on the source of Q7808, If resistors, are they ok? What about D7805 & D7806, something is stoping that pfc circuit from working, and it's not that complicated of a circuit. Something is causing it not to produce the 380vdc but not shorting the raw 160v.

                      Did you check if Q7601 & Q7602 are ok? I suspect if they were shorted you would not have the 160v raw B+ either.
                      Last edited by R_J; 04-02-2020, 09:44 AM.

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                        #51
                        Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                        Originally posted by R_J View Post
                        That's around 7 volts peak, correct? that should turn on the fets, YES



                        there are 6 resistors (or are they jumper wires?) on the source of Q7808, If resistors, are they ok?

                        6 in parallel - together they appear as about 1/2 OHM


                        What about D7805 & D7806, Both check good - had to take out of circuit to test

                        something is stoping that pfc circuit from working, and it's not that complicated of a circuit. Something is causing it not to produce the 380vdc but not shorting the raw 160v.

                        Did you check if Q7601 & Q7602 are ok? Not shorted - both check good.


                        I suspect if they were shorted you would not have the 160v raw B+ either.

                        What next?

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                          #52
                          Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                          The 6 parallel resistors are 0.51 Ohms each. I used a better meter and the combined resistance measures closer to 0.1 Ohms, but I don't think I can measure accurately enough to tell if one or more of them have opened. If one has opened, that could cause the chip to sense over-current prematurely and shut off the gate drive, but the resistors look good so I doubt that any of them are open.

                          The output gate drive seems low at 7v... from the spec sheet it looks it should be reaching VCC-2v under lighter loads, which would be near the clamp voltage of 12V. I am going to look closer at the pre-driver circuit to see what is loading the pin 7 output so much.

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                            #53
                            Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                            Attached Files

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                              #54
                              Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                              The 0.5Ω resistors will be fine, It would take both fets to short to open all of them, I would check R7823 that connects the CS to those resistors.
                              In the past I have seen where the source resistor(s) open and that blows the resistor that connects the CS pin, and without this feedback the ic would not startup.
                              Last edited by R_J; 04-10-2020, 07:37 PM.

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                                #55
                                Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                                R7823 is 10 OHMs and tests good. The waveform is at the CS pin 4.

                                Attached Files

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                                  #56
                                  Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                                  Attached Files

                                  Comment


                                    #57
                                    Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                                    So the fets are trying to operate, otherwise there would be no waveform on the CS, I guess you could try lifting R7641, that would isolate the pfc output to the main supply.

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                                      #58
                                      Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                                      Good idea. Will try.

                                      Comment


                                        #59
                                        Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                                        I lifted R7641 and no changes, so it does not appear to be load related. I'm going take another reading across the current sense resistors with the scope and try to get the waveform in-sych with ZCD and CS. It looks like either the ZCD or CS inputs can reset the gate drive and perhaps that may be happening prematurely due to one of those inputs.

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                                          #60
                                          Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

                                          Thanks everyone for your advise. This is just taking too long, so I am going to part this unit out. Anyone need any of the other boards?

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