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Harman Kardon AVR 25II Relay keeps ticking

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    #1

    Harman Kardon AVR 25II Relay keeps ticking

    Guys, anyone had this issue before? When the amp is cold and newly plugged in to power and when press the standby button, the power relay goes ticking on n off pretty fast, then when it gets a bit warmer, the relay ticking goes slower and slower and then no more ticking. But it DOES goes on protection mode there after as it goes back to standby mode when press the power button.

    Its a Harman Kardon AVR 25II. I have already resoldered all the cold joints. Checked all the output transistors. All good.

    Looks more like some capacitors are gone or maybe the voltage regulators dying. Any suggestions?

    https://www.youtube.com/watch?v=9ckT...ature=youtu.be
    Attached Files
    Last edited by DjKrish; 02-22-2018, 08:11 AM.
    Tags: None
    #2
    Re: Relay keeps ticking

    Does the amp eventually come on? if it does, then check the DC voltage on each sections output, You can check that voltage at the common point of the .27 ohm 5watt resistors in the output section. (R273,R274) etc. That voltage needs to be near zero volts. If it is more that +/- 1 volt, that channel likely has a problem
    Also check the voltage on the relay coil, Check on R701, you should have about 11 volts, if it is low, C704 could be bad.
    Try using a heat gun/hairblower and see if you can heat a section that will cause the amp to stay on, It is very likely a bad cap as this is an old amp.
    Last edited by R_J; 02-22-2018, 12:20 PM.

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      #3
      Re: Relay keeps ticking

      Manage to fix the relay ticking problem. Theres about 8 small electro caps gone bad on the power board and the main board power section. But it still goes to protection mode after few seconds turning on.

      1 problem solved. Now the protection part. If i pull the flex cable that connects from the main to display panel, it stays on. I believe the protection is in that circuit.

      Comment

        #4
        Re: Relay keeps ticking

        Just unsoldered Q262L and Q263L as it was reading high voltage on the resistor. Turned on the unit, no more protection. The rest of the channels are fine, zero voltage on the resistor.

        The thing is, ive measured Q262L and Q263L with a multimeter, theres no SHORT. Its working as it should. This is pretty confusing
        Last edited by DjKrish; 02-24-2018, 05:52 AM.

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          #5
          Re: Relay keeps ticking

          Because the amp is DC coupled one of the drive transistors in that channel could be bad, it may only be leaky and not shorted. also check the resistors like r269l, r268l, r264l, r272l, if they open it will unballance the amp. It could also be caused by a bad cap in that ciruit

          Comment

            #6
            Re: Relay keeps ticking

            The main power filter cap to drive the transistors has 2 unit. 1 has voltage, another has no voltage. zero. I suspect its the transformer. Now checking service manual.

            Comment

              #7
              Re: Relay keeps ticking

              Anyone happens to have service manual for avr25II? The one i downloaded is seriously the worse ive ever seen. And its half. Cant see anything clearly.

              Comment

                #8
                Re: Relay keeps ticking

                Originally posted by DjKrish View Post
                Just unsoldered Q262L and Q263L as it was reading high voltage on the resistor. Turned on the unit, no more protection. The rest of the channels are fine, zero voltage on the resistor.

                The thing is, ive measured Q262L and Q263L with a multimeter, theres no SHORT. Its working as it should. This is pretty confusing
                If the rest of the channels are working Why would you think there is a problem with the transformer??
                What do you mean when you say the "main power filter cap to drive the transistors has 2 unit" do you mean TWO connections?
                If thats what you mean, one of the connections goes to ground.
                The 2 filters for the outputs are C241 (on the positive side +51 volts) and C242 (on the negetive side -51 volts)
                Last edited by R_J; 02-24-2018, 08:43 PM.

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                  #9
                  Re: Relay keeps ticking

                  The transformer as you can see in the picture, the red cables both has 40v supply and the yellow has none, zero. Is that correct? The red red yellow cable is the supply for the filter caps. Because i see only 1 filter cap is powered and the other has zero voltages.

                  Comment

                    #10
                    Re: Relay keeps ticking

                    Now i spot 2 problems. The 2 middle transistors receiving high voltage on the resistor legs. And some of the channels not receiving voltage due to one of the filter caps is not receiving any voltage.

                    Comment

                      #11
                      Re: Relay keeps ticking

                      The transformer is center taped. Red - yellow - Red
                      If there was a problem with the transformer HOW do you explain the fact that the other channels are working??????????
                      SEE POST #3
                      Look at page 46 of the manual, that CP241 should be the plug. Red to one side of bridge rectifier. yellow (goes to ground) Red goes to other side of bridge rectifier.
                      Last edited by R_J; 02-24-2018, 10:03 PM.

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                        #12
                        Re: Relay keeps ticking

                        Im not actually saying other channels are working yet as i havent test it with a speaker yet. What i meant was there's no high voltage on other resistors except for the 2.

                        Comment

                          #13
                          Re: Relay keeps ticking

                          That because there is only a problem with ONE channel. BY removing the output transistors from the bad channel the amp is no longer in protection because the other channels are likely ok. Hook up a speaker to test the working channels. you are looking in the wrong place for a problem
                          The other channels will have zero volts on those resistors because they ARE working, The channel that has the high voltage on the resistors is NOT working
                          Last edited by R_J; 02-24-2018, 10:10 PM.

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                            #14
                            Re: Relay keeps ticking

                            My apologies i accidentally checked it with AC setting and not DC setting. The both filter caps are fine receiving correct voltages

                            Ok i will test the other channels with speakers and update here.

                            Comment

                              #15
                              Re: Relay keeps ticking

                              Ive already tested all the outputs with speaker, NOPE no sound. Since the 2 output transistors has been popped out from the circuit, it doesn't go protection anymore but there's no sound at all at any channels. When i turn on, the relay works both power and sound relays.

                              Comment

                                #16
                                Re: Relay keeps ticking

                                Any other place should i be lookin at?

                                Comment

                                  #17
                                  Re: Relay keeps ticking

                                  Does this reciever have front MAIN IN and PRE OUT jacks on the back?

                                  Comment

                                    #18
                                    Re: Relay keeps ticking

                                    yes. could that be it?

                                    Comment

                                      #19
                                      Re: Relay keeps ticking

                                      Are the jumpers in ????? If NOT you need to connect Main In (left) to Pre OUT (left) and do the same with the Right
                                      After you install the jumpers, you should have sound on the working channels, now you can start troubleshooting the bad channel
                                      Last edited by R_J; 03-02-2018, 11:51 AM.

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                                        #20
                                        Re: Relay keeps ticking



                                        its already connected , still no sound

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