Amp repair

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  • Nuthed
    Senior Member
    • Jan 2007
    • 151

    Amp repair

    Does anyone have any opinions about having components repaired at local repair shops versus sending them back to the factory for repairs? If the local shop has a good reputation does it still matter? Would they use the same parts? These are questions I will have to ask them I guess.

    What I'm referring to is my prized RB980BX. My 16 month old son decided to pull out the cables from one speaker, something he had just seen me do when I replaced the connectors. The problem is I was playing music at the time. Well now the right channel has no output, so he must have shorted it.
    Main System

    RSX-972 driving center and surrounds
    RB980-BX driving mains
    Paradigm Monitor 9s V5
    Paradigm Monitor C-390 V5
    Paradigm Monitor Atoms V5
    SVS PB-12
  • Kevin D
    Ultra Senior Member
    • Oct 2002
    • 4601

    #2
    Chances are it just blew a fuse. Something you or a local repair shop should be able to handle.

    Kevin D.

    Comment

    • Nuthed
      Senior Member
      • Jan 2007
      • 151

      #3
      Thanks.
      Should I just pop the cover off and look for a blown fuse? Any idea where this fuse would be located?
      Main System

      RSX-972 driving center and surrounds
      RB980-BX driving mains
      Paradigm Monitor 9s V5
      Paradigm Monitor C-390 V5
      Paradigm Monitor Atoms V5
      SVS PB-12

      Comment

      • Kevin D
        Ultra Senior Member
        • Oct 2002
        • 4601

        #4
        Yeah just pop the cover and start tracing the right channel. I've never pulled a cover on a 980, but there's probably going to be several fuses per channel. You might need a multi-meter to verify if a fuse is good or not.

        Kevin D.

        Comment

        • Nuthed
          Senior Member
          • Jan 2007
          • 151

          #5
          Going to Radio Shack tonight after work, found 2 blown fuses on the right channel. I hope there isn't another circuit board under the large one. They were both 125 volt, 5 amp fuses.
          Main System

          RSX-972 driving center and surrounds
          RB980-BX driving mains
          Paradigm Monitor 9s V5
          Paradigm Monitor C-390 V5
          Paradigm Monitor Atoms V5
          SVS PB-12

          Comment

          • peterS
            Super Senior Member
            • Dec 2005
            • 1038

            #6
            id say dont
            although it is common for this amp to blow fuses with no damage putting in a cold fuse in a damaged board will just fry it more
            considering the circumstances damage is a definate possibility - id put in a lower amperage fuse first to see if it pops on start up
            i sent mine in (not a fuse problem) for $40 shipping and they even did some upgrades

            Comment

            • Kevin D
              Ultra Senior Member
              • Oct 2002
              • 4601

              #7
              Different amp then the RB1080. Older and I'm sure out of warranty.

              I also disagree on the fuse statement. If whatever over-voltage that caused the fuse to blow is still present, a new fuse isn't going to suddenly allow anymore current through then the fuse (and subsequent parts) will allow.

              Being the channel went out while cables were improperly removed, I think we can rule out catastrophic unknown damage.

              Kevin D.

              Comment

              • peterS
                Super Senior Member
                • Dec 2005
                • 1038

                #8
                Originally posted by Kevin D
                Different amp then the RB1080. Older and I'm sure out of warranty.

                I also disagree on the fuse statement. If whatever over-voltage that caused the fuse to blow is still present, a new fuse isn't going to suddenly allow anymore current through then the fuse (and subsequent parts) will allow.

                Being the channel went out while cables were improperly removed, I think we can rule out catastrophic unknown damage.

                Kevin D.
                fuses blow due to current
                the voltage will actually sag in such a situation
                and yes a cold 5 amp fuse will allow higher levels of current longer than a 5 amp fuse that is warm

                id say a near 0 ohm load is as catastrophic as one can do to the output stage of an amp

                chances are that the fuses did there job by blowing before damage was done but if you can eliminate all chance by buying an additional $.50 fuse id do it

                here is a simple chart for exceeding the amperage of a fuse and the amount of time it takes to blow

                %of amp rating Opening time
                110% 4 hours minimum
                135% 1 hour maximum
                200% 5 minutes maximum

                so if its not already clear, upon startup a damaged circuit will generally draw more current than normal hence a lower amperage fuse will pop sooner preventing further damage while simultaneously signifying that there is a problem

                Comment

                • Nuthed
                  Senior Member
                  • Jan 2007
                  • 151

                  #9
                  $2.99 for a 4 pack of 5 amp 125 volt fuses. Used 2 of them.....kept them in my pocket on the way home so they stayed warm. Just kidding :T
                  Everything is fine and working great.
                  Main System

                  RSX-972 driving center and surrounds
                  RB980-BX driving mains
                  Paradigm Monitor 9s V5
                  Paradigm Monitor C-390 V5
                  Paradigm Monitor Atoms V5
                  SVS PB-12

                  Comment

                  • wkhanna
                    Grumpy Old Super Moderator Emeritus
                    • Jan 2006
                    • 5673

                    #10
                    Yes. The type of fuse in this amp (I have two RB980 BX's I've been abusing for over 13 years) is a metallic filament with a fixed resistance just like a resister, in a glass enclosure typically referred to as a ‘bus’ fuse. When a short occurs in a circuit, current rises and causes more heat to be generated by the resistance of the filament. When the fuse sees current higher than its predetermined rating, the resistance created by the filament is converted to heat, and the filament will melt at a predetermined temperature.

                    I have had occasion to blow fuses more times than I care to admit in my amps; at least the times when it was MY fault. From power surges and lighting strikes, to brain fade acts of hooking up speaker wires with the system on; in all cases, simply replacing a blown fuse has restored my work horses back to their former performance while keeping the SPCA and audiophile police from my door.

                    Turn-on current spikes may cause more damage in an already damaged circuit, but maybe we both are just lucky fools!

                    All I know is these amps have proven to be rock solid and well designed, IMHO!
                    _


                    Bill

                    Practicing Curmudgeon & Audio Snob
                    ....just an "ON" switch, Please!

                    FinleyAudio

                    Comment

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