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Yamaha RX A3020

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    Yamaha RX A3020

    Hello friendly Badcaps community.
    I have one of these on my desk today, and I have attached a service manual if it is beneficial to anyone.
    It turns on OK but no audio output to speakers unless the 'pure direct' button is pressed, and even then after 30 seconds, audio stops.
    There is no relay click when the sound stops, so not a relay control problem.
    Headphone audio stops when speaker audio stops, so not likely a power amp problem.
    It does not appear to be in any protection mode.
    Factory reset has made no change.
    After the first attempt to get sound, the problem takes less time to occur (5 sec), so temperature seems to be relevant.
    Allowing a cool off time (placing in standby), returns 30 sec of audio function again.
    Using headphone output to monitor audio instead of speakers does not change behaviour either.
    So it appears something is getting hot and inhibiting audio.
    FLIR imaging shows Q1810 and Q1809 getting hot, however I'm not sure if this is relevant.

    I've been burned before by going after hot components that are normally running hot, pun intended. So I'm asking if anyone else has come across this sort of behaviour in these devices and if the problem was indeed found within the 'AMPPOWER (1) board or elsewhere?

    Many thanks in advance for your shared wisdom.

    #2
    Re: Yamaha RX A3020

    I have found some devices with a similar error that was due to dirt (mostly sticky liquids) that when heated, increased the conductivity in some areas.
    This might not be your case, but I don't know what else it could be.

    Maybe there is a temperature sensor that makes it go into protection mode, although it is rare because otherwise it would generate an error or disconnect the relays. Just to try, you could try to heat the sensor to see if it disconnects earlier.

    In order to discover where is the conflictive zone located, you can try to heat up some small areas while testing....

    Comment


      #3
      Re: Yamaha RX A3020

      Thanks Victorcas, no sign of liquid spills, but just in case I sprayed out the boards with IPA and compressed air.
      Removed quite a bit of dust but unfortunately the problem remained unchanged until....

      The circuit shows Q1810 and Q1809 conduct the entire +-60V supply to the amplifiers.
      So they are likely to run hot anyway, so I'm putting that down as a red herring.

      For the sheer pleasure of it, i went through the Idling current adjustments.
      Once this was complete and all the channels were within the 15+-2mV spec and <100mV DC at the speakers, reconnecting the speakers gave reliable full output, even without the 'pure direct' button engaged !!!
      So I thought that was it? but no, after about 5 minutes the problem returned.......
      Checked idle current adjustments, all still within spec....
      Let it cool and OK again but only on pure direct.

      I did notice that when I had output on all channels, I had engaged the 'straight' button which seems to direct stereo input to all channels. A bunch of 'icons' on the display lit up when this was working well, but these indications are now absent from the display.
      Quite peculiar....

      Anyone had any similar woes with these heavy devices?

      Comment


        #4
        Re: Yamaha RX A3020

        Having a similar issue with a Marantz. Any BGA devices in the audio chain on that board by any chance ?

        Comment


          #5
          Re: Yamaha RX A3020

          No BGA's fortunately.

          Comment


            #6
            Re: Yamaha RX A3020

            what inputs have you tested with? What kind of signal input do you have access to? Do you have a scope to look for signals along path? Did you check at the pre-outs? A picture of the display when powered up might help. Any difference when the tuner is selected?
            Last edited by budwich; 12-10-2021, 11:08 AM.

            Comment


              #7
              Re: Yamaha RX A3020

              Does it behave the same if you connect more load to the output? (or increasing the volume) I say this in case the problem could be due to the power stage or the audio processing area.
              If you connect it with the audio very low and the same thing happens at the same time, I guess the problem would not be the power stage.

              If its the audio processing area, and there is not a BGA IC, it could be an LGA IC. Maybe you could try applying heat to some of these chips to see if the error occurs.

              Comment


                #8
                Re: Yamaha RX A3020

                Had the same problem with my RX-A2010 and have now solved it.

                Running Self Diagnostic Test C2.1 which test bus communication to DSP2 on digital2 PCB on the receiver didn't get anything, neither ok or faulty. Couldn't even check the firmware version. So with that test it seemed the problem lay within the DSP2 chipset on the Digital 2 P.C.B.

                Checked the possibility to order a new Digital 2 P.C.B. and they are still available for around €100.

                I thought I'll first will try to bake the PCB in the oven before I order a replacement.

                Placed it on a piece of wood in the oven on 200°C (392°F) for 15 minutes with the DSP2-chip facing down and resting straight with help of the board power socket, chassi mounting and the cable tie that is mounted on the board. I let it cool down and then mounted it again and now it works perfectly and the self diagnostic test are all ok regarding firmware version, checksum and the bus signal to the DSP2.

                Saved me €100

                Comment


                  #9
                  Re: Yamaha RX A3020

                  Originally posted by SlimMoses View Post
                  Had the same problem with my RX-A2010 and have now solved it.

                  Running Self Diagnostic Test C2.1 which test bus communication to DSP2 on digital2 PCB on the receiver didn't get anything, neither ok or faulty. Couldn't even check the firmware version. So with that test it seemed the problem lay within the DSP2 chipset on the Digital 2 P.C.B.

                  Checked the possibility to order a new Digital 2 P.C.B. and they are still available for around €100.

                  I thought I'll first will try to bake the PCB in the oven before I order a replacement.

                  Placed it on a piece of wood in the oven on 200°C (392°F) for 15 minutes with the DSP2-chip facing down and resting straight with help of the board power socket, chassi mounting and the cable tie that is mounted on the board. I let it cool down and then mounted it again and now it works perfectly and the self diagnostic test are all ok regarding firmware version, checksum and the bus signal to the DSP2.

                  Saved me €100
                  Just in case where did you find the Digital 2 PCB?

                  Comment


                    #10
                    Re: Yamaha RX A3020

                    Originally posted by budwich View Post
                    what inputs have you tested with? What kind of signal input do you have access to? Do you have a scope to look for signals along path? Did you check at the pre-outs? A picture of the display when powered up might help. Any difference when the tuner is selected?
                    Thank you for your questions.
                    I'm testing with the tuner input.
                    I have access to a function generator.
                    I have a scope.
                    Not checked pre-outs.
                    Display output is normal, no errors, not in fault mode.

                    Comment


                      #11
                      Re: Yamaha RX A3020

                      C2.1 on this one is network check. Shows all ok so long as you connect it to a network switch.
                      C1.7 however is more interesting as it shows NG.
                      BUS DSP1 is reporting an error then.
                      IC911 on the DIGITAL (1) board.
                      Will take a look around there.

                      Comment


                        #12
                        Re: Yamaha RX A3020

                        Fascinating.
                        At 50 degrees C, DSP1 (IC911) is happy, everything works,
                        at 45 degrees C, it stops.
                        Regular and repeatable.
                        Using a thermostatically controlled heat gun, I baked the chip at 150 degrees C for 15 minutes.
                        So far the bakeout appears to have been successful and all channels are running again.
                        Thanks SlimMoses !

                        Comment


                          #13
                          Re: Yamaha RX A3020

                          Originally posted by Andrealikescaps View Post
                          Fascinating.
                          At 50 degrees C, DSP1 (IC911) is happy, everything works,
                          at 45 degrees C, it stops.
                          Regular and repeatable.
                          Using a thermostatically controlled heat gun, I baked the chip at 150 degrees C for 15 minutes.
                          So far the bakeout appears to have been successful and all channels are running again.
                          Thanks SlimMoses !
                          I'm happy it worked for you too!

                          Comment

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