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Harman Kardon AVR1700 not powering up

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    Re: Harman Kardon AVR1700 not powering up

    Can you show new photos and indicate where the wick touched the board? I hope you were not trying to solder on the board while it was live!?

    D904 and R911 are to do with IC93, so they won't be the reason why you have no voltage at D911. Something else has been blown too.


    Check the resistance to ground across D914 and check R926 and R927 are not blown
    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
    -David VanHorn

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      Re: Harman Kardon AVR1700 not powering up

      I have discharged C902(all this time) and I have assumed that it is all gone, but I was mistaken.
      I have dragged the wick by mistake, on that area of the primary, so it is hard to tell, what I have touched. The big spark, it happened at that spot, though.
      Later, I will test those parts.

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        Re: Harman Kardon AVR1700 not powering up

        R926 and R927 are OK. D914 seems OK out of circuitry(.437V), but the resistance is too low, at 402 Ohms.
        I have tried another 18V zener, but it blew up(popped). Maybe it wasn't the right one.
        Digikey page:
        https://www.digikey.com/product-deta...SCT-ND/4885314

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          Re: Harman Kardon AVR1700 not powering up

          Did you install the new D914 the right way around? Zeners are used "backwards" compared to other diodes.

          Also, if IC91 was shorted, there could be ~300v DC going straight into D914 without the current limiting from R926 and R927.
          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
          -David VanHorn

          Comment


            Re: Harman Kardon AVR1700 not powering up

            You maybe right, about the diode orientation. I will have to check on that, because the old one lost it's mark, so I did not see the orientation right. The new diode, has a line on it and on the pcb, the line points the way, that I have installed the diode.
            Maybe the IC is shorted? I will check on it, but now, I have to install my patio sliding door.

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              Re: Harman Kardon AVR1700 not powering up

              I can't see the silkscreen in the photos, but with D914, the line on the package (which denotes the Cathode) should face towards R928 and also the wire link heading off towards R927.
              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
              -David VanHorn

              Comment


                Re: Harman Kardon AVR1700 not powering up

                OK, I'm back to this.
                Like somebody else here on the forum, with a 3700, had a bad standby transformer, I had the same issue myself.
                I have ordered one, from Harman(~8).
                I have tested the components on the primary side and I have found two resistors R935 and R932 bad. They were showing high values. I have replaced them temporarily, with 805 side ones(I don't know there wattage).
                I have also measured IC91 and I have found very low ohm value between 1&2 pin and 7 & 8(ground) pins.
                I have replaced that IC, as well.
                Now I have standby voltage, yesssss. Finally.
                I also have the 34V, at CN66 plug. But pretty much all I have.
                Now what else could be the problem?
                I don't have +/-12V, or +/- 45V.

                Comment


                  Re: Harman Kardon AVR1700 not powering up

                  Great! Good that you were able to get a new transformer so easily!

                  So it looks like IC91 is working all OK now, the +35v rail is generated from the same TF91 transformer using IC99 and D929.

                  So the next part to look at will be the circuitry of IC92 for the +/-12v rails. First check would be, is IC92 receiving Vcc on Pin 7 and the rectified mains voltage getting to TF92?

                  But one thing I don't understand, what do you mean when you said you replaced R935 and R932 "with 805 side ones"?
                  Last edited by Agent24; 09-07-2017, 02:20 PM.
                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                  -David VanHorn

                  Comment


                    Re: Harman Kardon AVR1700 not powering up

                    0805 size, sorry.
                    I have removed these resistors, from some TV power supply boards.
                    I will check those voltages soon, and I will be back with the results.
                    Thanks for getting back with me, I appreciate it a lot.
                    What do you think, that this power supply, it should boot up fully, without the rest of the receiver?
                    Last edited by tibimakai; 09-07-2017, 02:31 PM.

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                      Re: Harman Kardon AVR1700 not powering up

                      IC92 is not getting anything at pin #7.
                      At the Q903 at the base and emitter, I get 3.4V, but 0V at collector. Transistor looks OK.
                      Zeners, resistors are OK as well.
                      At pin 4 & 5, I get 327V.
                      Pin #7 to ground, is over 15k Ohm.
                      Last edited by tibimakai; 09-07-2017, 09:19 PM.

                      Comment


                        Re: Harman Kardon AVR1700 not powering up

                        Oh right. Well if the originals were 0805 size as well then they should be fine, the wattage rating will most likely be the same.

                        Sorry myself, I forgot about the control signals. Yes, IC92 will not receive any power until the mainboard instructs the PSU to come up out of standby with the POWER_HI line at Pin 13 of BN65.
                        You could try just jumpering this to Pin 12\ST+5V rail, and IC92 should start.

                        The same goes for the +/-45v supply on the AMP_VCC_ON (Pin 14) line.
                        "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                        -David VanHorn

                        Comment


                          Re: Harman Kardon AVR1700 not powering up

                          The original resistors, were a bigger package. Most likely 0603.
                          With pin #12 and ST+5V shorted, I', getting 0.8V at the pin #7 of IC92.
                          At the Q903, I'm getting higher voltages as well, 5.6V, 5.1V and .8V.
                          With pin #14 shorted to ST+5V nothing happened, still 0V at +/-45V.
                          Last edited by tibimakai; 09-08-2017, 03:53 PM.

                          Comment


                            Re: Harman Kardon AVR1700 not powering up

                            0603 is smaller than 0805, but in any case, if you replaced the originals with smaller ones, you should replace them with the correct size (and wattage) at the end.

                            It sounds like something is wrong with the Vcc supply to IC92. The ICE2B365 datasheet says it needs at least 8.5v to start. If you're only getting 5.6v that's not enough.

                            The voltage out of D920 and at the emitter of Q903 should only be a little lower than the voltage to IC91 through D911, due to R935, but it should not be that low. Check R935 is OK and soldered in correctly.

                            If the 16v zener, D918 was damaged and leaky it could pull the voltage down.
                            Additionally, if D920 was bad (leaky or partially open circuit) it could cause the low voltage problem too.
                            Attached Files
                            "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                            -David VanHorn

                            Comment


                              Re: Harman Kardon AVR1700 not powering up

                              Here is the result, of finding a leaky D918:
                              Attached Files

                              Comment


                                Re: Harman Kardon AVR1700 not powering up

                                After replacing it, I had 11.8V there(IC92 pin #7 and at Q903). All the voltages came up at the connectors.
                                Though, the power for the amp, is only a +/- 25V and not +/- 45V, as expected.
                                HDMI audio/video works well too.
                                I still need to replace, those two resistors and clean up everything.
                                The PS is very messy, after all this work on it.
                                It's been a while, since I started on this receiver, I don't even have the original screws anymore, need to find some, that match with the rest.
                                Thank you very much, for all your help with this receiver.
                                I appreciate it a lot.


                                Tibor
                                Last edited by tibimakai; 09-10-2017, 03:57 PM.

                                Comment


                                  Re: Harman Kardon AVR1700 not powering up

                                  No worries! Glad to see you finally got it working
                                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                  -David VanHorn

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