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Yamaha RX-V3900

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    Yamaha RX-V3900

    Hi guys, I have this Yamaha for repair, the problem is when I push Power ON,, the amplifier goes Off in 1 second, I try Hard reset, same problem, I change all the capacitors on the Ic regulator circuit and same problem, I check all the audio output transistors all are good, I check voltage on Regulators board and I have a little low voltages on circuits like on 12 volts I have 11.6 volts, on -12 volts I have -11.4 volts , on 5 volts I have 4.81 volts, could someone tell me what I have to check now?

    #2
    Re: Yamaha RX-V3900

    Look at this thread for information and things....
    https://www.badcaps.net/forum/showth...t=yamaha+v3900

    hopefully, you can get to the self-diagnostics and see what the results are.
    Last edited by budwich; 02-17-2022, 05:06 PM.

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      #3
      Re: Yamaha RX-V3900

      I try but I cannot because when I push Power On the amplifier shutoff immediatly

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        #4
        Re: Yamaha RX-V3900

        what process are you following to get into the diagnostic menu? Follow the sequence in the manual

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          #5
          Re: Yamaha RX-V3900

          Self-diagnostic mode by holding down the 'enter' &preset tuning> buttons while pressing in the master on/off switch repeatedly many times but the message 'MAIN ON' stays on nothing else happening.I think the system has locked itself in.I try another thing , I push Info and Straight and put the Ac cord it's write Firmware update ( blinking) in the display but when I release these 2 buttons the amplifier goes Off
          Last edited by Fripacks; 02-19-2022, 09:43 AM.

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            #6
            Re: Yamaha RX-V3900

            :-(... I have seen in the manual that if the system is in fault mode, you have to unplug it from the wall before trying to get into the self-diagnostics. Further, you don't keep repressing the power on key. According to the manual, you just press it once (to the ON position... it should be in the OFF position when unplugged) while holding the other two keys and wait for the appropriate display, then release them.
            Last edited by budwich; 02-19-2022, 12:48 PM.

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              #7
              Re: Yamaha RX-V3900

              I try this thing too, always same problem, shut off in fraction of second

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                #8
                Re: Yamaha RX-V3900

                just for confirmation.... you are using the master on/off button which is a "push in / out" button versus the "on/off standby" button which is a momentary button.

                what's the history of the problem / unit?

                there is a 9v "supply" along with -5v and 3.3v. You might list all the voltages that you checked on the power supply area specifically.
                Last edited by budwich; 02-21-2022, 12:35 PM.

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                  #9
                  Re: Yamaha RX-V3900

                  you might need to monitor the PDET line while you attempt your power up sequence to see what happens.

                  does the display light and display anything before it shuts down?
                  Last edited by budwich; 02-21-2022, 09:48 PM.

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                    #10
                    Re: Yamaha RX-V3900

                    If it's going into protect due to over voltage or over current then you have to remove that condition first. The way to do that is to unplug one of the cables going from the hdmi board to the main board.

                    You'll have to have a look further or post some pictures as I have no idea about the receiver in question here.

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                      #11
                      Re: Yamaha RX-V3900

                      I try disconnect all connectors on HDMI board always same problem, see the photos
                      Attached Files

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                        #12
                        Re: Yamaha RX-V3900

                        Someone?

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                          #13
                          Re: Yamaha RX-V3900

                          You can't disconnect ALL connectors. Try them one at a time or find the service manual for less guess work.

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                            #14
                            Re: Yamaha RX-V3900

                            Did you check the output voltages on the DCCNVT pcb?
                            I had an issue with the board, Channel 2 4.3v Dc. Rail was < 0.4VDC.
                            This was triggering the protect mode.
                            Note: During this fault you could not enter diagnostics mode, but could activate PSU’s to test voltages using the diag mode.
                            Replaced the DCCNVT board, problem resolved.

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