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    Yamaha RX-V581 going into protection mode

    Hi all,

    I have a Yamaha RX-V581 which has started going into protection mode on startup. If I have speakers plugged in when powering it on, I hear a quick loud pop noise before it shuts off.

    When putting it into diagnostic mode, the message displayed is DC PRT: 000. I took it into a repair centre, who after taking $120 to quote on the device, who said there's a DC voltage on the rear right channel. They also said it'd be another $360 plus parts to fix it, so as you might expect, I declined.

    So far all of the work I've done with electronics so far has been very basic, so an AV receiver with faulty components is all new territory for me. All I've done so far is replace obviously-damaged components on monitors, - not diagnosis. With that out of the way - I have done a bit of scouring online, and have been unable to find a manual for this particular model. If I'm right and the RX-Vx81 series are all similar, I did come across a copy of the RX-V381 manual on Elektrotanya and uploaded it here: https://www.scribd.com/document/4250...service-manual (it was higher than the PDF attachment size limit).

    After reading some previous threads here - from what I can tell, I need to check the output transistors - specifically for the surround channels, and that they're likely to be mounted on the very large heatsink inside. And by check, I expect I need to confirm DC on one of the surround channels with a multimeter, do a visual inspection, and then potentially probe for certain conditions. Am I going to ve looking for a short, of a voltage out of spec, or voltage where it shouldn't be?

    Do these things care if you power them up without some of the boards connected? I'm not sure how I can get readings from some of these without pulling boards out.

    I have also attached a couple of photos of the main board to see if your eyes can spot anything that I didn't.

    Let me know if you'd like specific photos, measurements, or have some general pointers.

    Thanks
    Attached Files

    #2
    Re: Yamaha RX-V581 going into protection mode

    check dc voltages at the centre pin of the 0.22 ohm resistors .should be 0v or a few mv .

    Comment


      #3
      Re: Yamaha RX-V581 going into protection mode

      Can I see the pictures of the bottom of the chassis?
      BTW, did the the repair shop leave some of the cables unconnected?
      Last edited by budm; 09-09-2019, 09:49 AM.
      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


        #4
        Re: Yamaha RX-V581 going into protection mode

        Photo of the underside attached.

        How do you go about getting it assembled and still being able to take measurements? Those resistors are under two boards so I expect this is going to be tricky.
        Attached Files

        Comment


          #5
          Re: Yamaha RX-V581 going into protection mode

          You will have to take it apart completely.

          Comment


            #6
            Re: Yamaha RX-V581 going into protection mode

            See service manual page 19 on how you must ground the assembly when troubleshooting the Main (1) PCB.
            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


              #7
              Re: Yamaha RX-V581 going into protection mode

              So I pulled the entire unit apart - detaching the heatsink and everything, only to see I didn't need to do that, and that here's a way to expose the underside and get a multimeter on everything. So I've put it all back together with the intention of strictly following the service manual to expose the underside and get some running voltages off of it.

              And I don't know if this gives anyone any pointers as to where I should start looking, but I'm seeing -19.5v on the SR channel when sticking the multimeter on the SR terminals.

              And, I don't know if it's any better than the last manual I'd uploaded, but I found the RX-V481 manual, and that been very accurate for my RX-V581 thus far: https://www.scribd.com/document/4257...81d-Service-En

              Comment


                #8
                Re: Yamaha RX-V581 going into protection mode

                Do you mean the SR "speaker terminals" That seems odd because if there is that much of an offset the amp should be in protection and the relay RY225 should not have closed
                Start by checking the dual emitter resistors R2254 and check the output transistors for that channel, compare with a good channel if you like.
                Last edited by R_J; 09-13-2019, 09:15 AM.

                Comment


                  #9
                  Re: Yamaha RX-V581 going into protection mode

                  I'm able to get that reading because I'm using the protection mode bypass of holding down Tone + Info as I hold the power button to turn it on.

                  Comment


                    #10
                    Re: Yamaha RX-V581 going into protection mode

                    I've done some probing around, using the attached page as a starting point. Measurements all taken with the unit turned off. Here's what I've found so far:

                    R2162 – 7.7k instead of 10k
                    R2156 – 84k instead of 270k
                    C2142 – 400-420
                    C2131 – 400-420
                    R2141 – 33K
                    R2113 – 33k
                    R2133 - 1200
                    C2106 – no short, don't remember value
                    R2106 – 1k
                    C2118 – no short, don't remember value
                    C2119 - 1960
                    R2121 – 1.8k
                    R2132 – 100
                    R2148 – 100
                    Q2119 – no short
                    Q2105 – no short
                    Q2112 – no short

                    I turned the meter to diode mode for the caps and transistors.

                    Could the results on the first two just be a problem with how I'm measuring? I did find it strange that as I measure R2156, the value was slow to climb until it hit 84k. Or could this be a symptom of something else?

                    Should I keep probing on the components on the second attachment?
                    Attached Files

                    Comment


                      #11
                      Re: Yamaha RX-V581 going into protection mode

                      Locate the same component etc. in a working channel and compare the readings The fault is not likely to be a capacitor. Check the resistors and transistors around the outputs, Q2160/2161 and the drivers Q2146/2147

                      Comment


                        #12
                        Re: Yamaha RX-V581 going into protection mode

                        I have a bit of an update on this one. TLDR: Haven't got anywhere.

                        After leaving the opened amp on the kitchen table for countless months, I finally summoned the motivation and plan to try tackling this again - not for lack of interest, but ability/plan.

                        From page 120 of the manual, I listed every component that I could see as being part of the "SR" circuit. I then stuck my multimeter on each component that I'd listed. For resistors, I used ohms, and for caps and diodes, I used diode mode. For each I compared the values to values from components on one of the other channels on the board - or in the case of resistors, I had reference values. The list of results is attached, as are a couple of shots of the underside of the board. Not sure if they'll be of use but they're here anyway.

                        Some of them don't make a lot of sense - I assume it's because I'm testing the components in-situ and they'd need to be tested in isolation for a useful reading.

                        I haven't actually tried powering the amp on in protection override mode and taking measurements - I've never actually taken readings from a device that's on and don't know how safe it is to the device to do it like that.

                        I'm open to suggestions - I'm lost as to where I can go from here.
                        Attached Files

                        Comment


                          #13
                          Re: Yamaha RX-V581 going into protection mode

                          Taking a different approach, if I were to power the unit on in protection override mode, what would be some useful points to probe for voltages at?

                          Comment


                            #14
                            Re: Yamaha RX-V581 going into protection mode

                            Did you ever find out what it was? I'm trying to nail down a -10V offset on one of my channels (yamaha RX-V577).

                            Comment


                              #15
                              Re: Yamaha RX-V581 going into protection mode

                              Unfortunately, I never did. The amp lies dormant on a shelf taking up space, still.

                              Comment


                                #16
                                Re: Yamaha RX-V581 going into protection mode

                                I did some retesting - results attached. Main differences were with D2113 to D2116.

                                Bearing in mind SL seemed to work OK, and SR has 50v on it - does anything in those results leap out as wrong?
                                Attached Files

                                Comment


                                  #17
                                  Re: Yamaha RX-V581 going into protection mode

                                  what are the voltages on the "rails"? It would appear the negative one is leaking thru to the output.

                                  Comment


                                    #18
                                    Re: Yamaha RX-V581 going into protection mode

                                    Where/how would I find the rails?

                                    Comment


                                      #19
                                      Re: Yamaha RX-V581 going into protection mode

                                      Hi
                                      My first post,
                                      Rails are a generic term used for locations for where you will find the main voltages that have been rectified from the Power supply. Ie most electronics use 5v on the circuit boards so will be easy to find.
                                      There might be 12v and 3.3 volts as well. Check the pins on connectors leaving the power supply if needed. Voltages don't have to be exact but close is good, high\low voltages can give you the protection overload.
                                      Hope that helps.

                                      Cheers

                                      Dave

                                      Comment


                                        #20
                                        Re: Yamaha RX-V581 going into protection mode

                                        It could be that D2114 is open, It should give a reading same as D2116, If it is open it will throw the bias off.

                                        Comment

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