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Harman Kardon AVR1700 not powering up

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    Harman Kardon AVR1700 not powering up

    Long story short, I'm putting together a receiver, from two receivers. Both had different issues. One missing the power supply, the other had a corroded HDMI board.
    The power supply does not work, it had two IC's blown(very visible), D901/D902 and I have found a bad resistor.
    I have replaced two blown ICs and resistor, but it still won't power on.
    I don't even have standby voltage.
    I measure 334V, at the transformer TF93's #7 pin.
    Q901 FET is getting 334V.
    The ICs, are not getting VCC at all.
    D914 zener diode shows .718V one way, but meter is not beeping. That is normal?
    Any help would be appreciated.
    Attached Files

    #2
    Re: Harman Kardon AVR1700 not powering up

    Here is my other thread, with pictures of the PS and a PDF file of the PS.
    https://www.badcaps.net/forum/showth...kardon+avr1700

    Comment


      #3
      Re: Harman Kardon AVR1700 not powering up

      OK, in the power supply:

      On capacitors C901 and C930: what voltage do you have?
      Don't buy those $10 PSU "specials". They fail, and they have taken whole computers with them.

      My computer doubles as a space heater.

      Permanently Retired Systems:
      RIP Advantech UNO-3072LA (2008-2021) - Decommissioned and taken out of service permanently due to lack of software support for it. Not very likely to ever be recommissioned again.
      Asus Q550LF (Old main laptop, 2014-2022) - Decommissioned and stripped due to a myriad of problems, the main battery bloating being the final nail in the coffin.


      Kooky and Kool Systems
      - 1996 Power Macintosh 7200/120 + PC Compatibility Card - Under Restoration
      - 1993 Gateway 2000 80486DX/50 - Fully Operational/WIP
      - 2004 Athlon 64 Retro Gaming System - Indefinitely Parked
      - Main Workstation - Fully operational!

      sigpic

      Comment


        #4
        Re: Harman Kardon AVR1700 not powering up

        I have 334V, up to the transformer.

        Comment


          #5
          Re: Harman Kardon AVR1700 not powering up

          i am wondering why there is 334v ? is it a switch mode supply ?

          Comment


            #6
            Re: Harman Kardon AVR1700 not powering up

            Yes. It is a switch mode power supply I believe.
            Don't buy those $10 PSU "specials". They fail, and they have taken whole computers with them.

            My computer doubles as a space heater.

            Permanently Retired Systems:
            RIP Advantech UNO-3072LA (2008-2021) - Decommissioned and taken out of service permanently due to lack of software support for it. Not very likely to ever be recommissioned again.
            Asus Q550LF (Old main laptop, 2014-2022) - Decommissioned and stripped due to a myriad of problems, the main battery bloating being the final nail in the coffin.


            Kooky and Kool Systems
            - 1996 Power Macintosh 7200/120 + PC Compatibility Card - Under Restoration
            - 1993 Gateway 2000 80486DX/50 - Fully Operational/WIP
            - 2004 Athlon 64 Retro Gaming System - Indefinitely Parked
            - Main Workstation - Fully operational!

            sigpic

            Comment


              #7
              Re: Harman Kardon AVR1700 not powering up

              Yes it is.
              I had repaired a couple of these in the past and other similar ones, like 1510 and 1610, but I always had at least the standby blinking.
              Last edited by tibimakai; 01-15-2017, 08:06 PM.

              Comment


                #8
                Re: Harman Kardon AVR1700 not powering up

                Originally posted by petehall347 View Post
                i am wondering why there is 334v ? is it a switch mode supply ?


                Hmm kind of... you have a graetz right before the caps so you should have half of yout AC there.
                check page 96 from the service manual.

                Comment


                  #9
                  Re: Harman Kardon AVR1700 not powering up

                  It is 334 VDC because it is Voltage double circuit.
                  So what blown parts did you replace?
                  Last edited by budm; 01-15-2017, 08:33 PM.
                  Never stop learning
                  Basic LCD TV and Monitor troubleshooting guides.
                  http://www.badcaps.net/forum/showthr...956#post305956

                  Voltage Regulator (LDO) testing:
                  http://www.badcaps.net/forum/showthr...999#post300999

                  Inverter testing using old CFL:
                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                  http://s807.photobucket.com/user/budm/library/

                  TV Factory reset codes listing:
                  http://www.badcaps.net/forum/showthread.php?t=24809

                  Comment


                    #10
                    Re: Harman Kardon AVR1700 not powering up

                    Hi Bud, I'm back with some "put away" stuff, like this receiver, I also came back to the Pioneer VSX-1122k, that nobody could help me(found that a 3.3V is missing) and an Infinity 475A car amp.

                    Comment


                      #11
                      Re: Harman Kardon AVR1700 not powering up

                      I have replaced: R908, D901, D902, IC91(OB2358L), IC92(ICE2B365).
                      D914(18V zener), when I measure it, it does not beep(in or out of circuit) and shows .718V.
                      Last edited by tibimakai; 01-16-2017, 08:41 PM.

                      Comment


                        #12
                        Re: Harman Kardon AVR1700 not powering up

                        If you measure a Zener forward biased, it will read the average silicon voltage drop, so 0.7v is normal. Because this is a little high though, perhaps the meter does not beep. Which way around do you get this 0.7v reading?

                        You would need to test the zener out of circuit reverse biased with current limiting to check Zener voltage.

                        Are R926, R927, R922 and R923 OK?
                        "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                        -David VanHorn

                        Comment


                          #13
                          Re: Harman Kardon AVR1700 not powering up

                          I believe all four resistors are fine. The 1.2Mohms show a bit weird, though(in circuit) start low and they are going higher and higher in value.
                          I will have to remove the zener and test it out, that way.

                          Comment


                            #14
                            Re: Harman Kardon AVR1700 not powering up

                            If there's no voltage supply getting to IC91 pin 1 and 2, then either those resistors are open\high or D914\D911 is shorted, C918 is bad, or IC91 itself is shorted to ground.

                            I can't see what else it would be.

                            OR somehow the wire link going between the primary capacitors to R926 is bad.
                            Last edited by Agent24; 01-17-2017, 01:18 AM.
                            "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                            -David VanHorn

                            Comment


                              #15
                              Re: Harman Kardon AVR1700 not powering up

                              IC91, is getting an oscillating voltage at D914, something between 8-12V.
                              The voltage should be 18V there, right?
                              With min/max I'm getting 12.6V.
                              At pins #5-6(drain), I'm getting 334V.
                              That is normal to oscillate?
                              The other two ICs, are net getting any voltage.
                              Last edited by tibimakai; 01-17-2017, 07:49 PM.

                              Comment


                                #16
                                Re: Harman Kardon AVR1700 not powering up

                                The startup Voltage at VDD pin 2 is 12.5V Typ., once the circuit starts running the IC will stop running until vdd drops down to 6.8V typ. see pdf page 4 and 7.
                                Vrify for sure that those two 1M2 resistors are good, they usually go up in value when they go bad.
                                You can also lift pin 1 and pin 2 of the IC off the board and check DCV across that 18V Zener.
                                Attached Files
                                Last edited by budm; 01-17-2017, 08:31 PM.
                                Never stop learning
                                Basic LCD TV and Monitor troubleshooting guides.
                                http://www.badcaps.net/forum/showthr...956#post305956

                                Voltage Regulator (LDO) testing:
                                http://www.badcaps.net/forum/showthr...999#post300999

                                Inverter testing using old CFL:
                                http://www.badcaps.net/forum/showthr...er+testing+cfl

                                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                http://s807.photobucket.com/user/budm/library/

                                TV Factory reset codes listing:
                                http://www.badcaps.net/forum/showthread.php?t=24809

                                Comment


                                  #17
                                  Re: Harman Kardon AVR1700 not powering up

                                  I have cut the trace and measured both resistances. Both show, 1.19Mohm. I have also cut the trace, after the zener and the voltage is, 17.97V.
                                  So, everything looks good, in my opinion. Most likely, the "load" has an issue(output source).

                                  Comment


                                    #18
                                    Re: Harman Kardon AVR1700 not powering up

                                    The load in this case is the pin 2 VDD pin of the IC, the startup current is supposed to be 5uA typ., unless the diode that is used for rectifier for the AUX winding that supposed to supplying the running Voltage once the circuit starts running has leakage resistance.
                                    You can not lift pin 2 off the board so anything else connected to the 18v Zener is still in place so you can test the Voltage without the IC load.
                                    Also if you monitor the DCV on the secondary side filter caps, do see the Voltage even jumps up at all?, If it does, it means the circuit did try to star up but goes into shutdown.
                                    Resistance between pin 3 and PRIMARY side GND is?
                                    D910, D928, OPTO PC92, d921, d943 are good?
                                    What DCV do you have on that standby power supply transformer T91 pin 1, pin 2 iwth ref to primary circuit GND? It should a little over 160VDC
                                    Last edited by budm; 01-17-2017, 10:47 PM.
                                    Never stop learning
                                    Basic LCD TV and Monitor troubleshooting guides.
                                    http://www.badcaps.net/forum/showthr...956#post305956

                                    Voltage Regulator (LDO) testing:
                                    http://www.badcaps.net/forum/showthr...999#post300999

                                    Inverter testing using old CFL:
                                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                    http://s807.photobucket.com/user/budm/library/

                                    TV Factory reset codes listing:
                                    http://www.badcaps.net/forum/showthread.php?t=24809

                                    Comment


                                      #19
                                      Re: Harman Kardon AVR1700 not powering up

                                      Pin #3 and primary grd(pin #7/8) is 5.4 Mohm.
                                      Now, I'm measuring a stable 17.93V at IC91, weird. Yesterday, I had an oscillating voltage.
                                      I have tried C944 at startup and it doesn't show any life.
                                      I'm doing these measurements with the connector disconnected from the HDMI board. The only connector that is connected is for the front panel(power button is there as well). That is correct, or should I connect that one as well? Power connector to the amp, it is not necessary at this time, right?

                                      Comment


                                        #20
                                        Re: Harman Kardon AVR1700 not powering up

                                        How do you test an opto? Some they show as a diode and some don't show as a diode, just a higher voltage ~1-2V.

                                        Comment

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