KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

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  • altavek
    Member
    • Jun 2013
    • 12
    • USA

    #1

    KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

    Apparently this was a known issue with these speakers. Can't seem to find any info on what exactly causes the problem though. Usually, I would replace the entire board but that is not any option anymore. Was hoping that someone here may have either encountered these specifically or something similar. I'm including pics of the inverter board. Thanks in advance!


  • Pentium4
    CapXon Be Gone
    • Sep 2011
    • 3741
    • USA

    #2
    Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

    Please post pictures using the attach function. You should upload some overhead shots of all the boards

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

      Straight shot of the top side of the board so we can see the components. Rectifier diodes will be the first thing to check, then the audio output transistors that are mounted on the heat sink.
      Last edited by budm; 06-05-2013, 08:51 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

      • altavek
        Member
        • Jun 2013
        • 12
        • USA

        #4
        Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

        Sorry about that. Here's the inverter board from overhead.
        Attached Files

        Comment

        • altavek
          Member
          • Jun 2013
          • 12
          • USA

          #5
          Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

          One more with the heatsink off
          Attached Files

          Comment

          • Khron
            Badcaps Legend
            • Sep 2006
            • 1350
            • Finland

            #6
            Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

            Gotta love how the copper bottom layer is silkscreened on the top - easier to trace stuff

            Hint: this is the "power board"; inverters are mostly found in UPS's (turning the battery DC into the AC that mains-powered things are fed with) or they supply fluorescent lamp (turning whatever DC they're fed with into the high-voltage AC the lamps need)

            As budm said, the first place to check would be the rectifiers - these are the four fat-ish "upright" diodes (D108, D110 and the other two like them, around the two big main filter caps). Just to be on the safe side, you could consider checking the small rectifier diodes too (D101-104, right next to the two white connectors).

            Seems these Rokits use some chip-amps to power the speakers -these are the two seven-legged devices that are screwed to the heatsink. What do the markings on those say?

            My guess is they're some TDA chips; LM1875's only have 5 legs. A quick search on Digikey turned up stuff like TDA2052, TDA7240 and TDA7298. I kinda doubt KRK went with anything more "exotic" than that
            Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

            Comment

            • altavek
              Member
              • Jun 2013
              • 12
              • USA

              #7
              Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

              Both the transistors say TDA2052

              How would I test the rectifiers? (Sorry, been a while since electronics class)

              Comment

              • Khron
                Badcaps Legend
                • Sep 2006
                • 1350
                • Finland

                #8
                Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                Those are $2.47 a pop, from Digikey

                Checking diodes is best done with them removed from the circuit (so that other components and connections won't interefere and cause false readings).

                You've got a (digital) multimeter, right? Switch that to the diode range (the -|>|- symbol), place the black probe on the "band" (cathode) terminal of the diode, and the red probe on the other end (anode). A good diode should show something in the range of 0.5-0.7 volts - this is the "forward voltage drop" that you'll find in datasheets.

                If it's higher than that (unlikely) or the meter goes "over the top", the diode failed open. If it's lower than that (in the 0.00x range), it's shorted
                Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                Comment

                • altavek
                  Member
                  • Jun 2013
                  • 12
                  • USA

                  #9
                  Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                  So just tested the diodes and the top one of these 4 (D102?) metered 000. So as soon as find my soldering iron, I'll pop it out and get a replacement. Thanks!

                  Should I go ahead and just replace the transistors while I'm at it?
                  Attached Files
                  Last edited by altavek; 06-06-2013, 08:35 PM.

                  Comment

                  • Khron
                    Badcaps Legend
                    • Sep 2006
                    • 1350
                    • Finland

                    #10
                    Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                    Mmm... Not just yet. Or better yet, pop all four diodes out, and using the Ohm (resistance) range on your meter, probe between the positive (+) rail and ground, and then the negative rail (-) and ground.

                    If neither of those shows a low resistance (give it a few seconds before drawing a conclusion, until those big caps charge up to the low voltage the meter provides), then it's safe to assume the two amplifiers are fine (PS: they're not just plain ol' transistors )
                    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                    Comment

                    • altavek
                      Member
                      • Jun 2013
                      • 12
                      • USA

                      #11
                      Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                      So I got the diode off. Markings are IN5392 GW. Not seeing this in DigiKey nor does a google search lead me anywhere useful. Suggestions?

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                        It is 1N5392, not I N 5392.
                        http://www.digikey.com/product-detai...ICT-ND/3711758
                        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

                        • lti
                          Badcaps Legend
                          • May 2011
                          • 2548
                          • United States

                          #13
                          Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                          If this is a common failure, you shouldn't use an exact replacement. Find one with a higher current rating. I don't think the voltage rating will need to be increased since it looks like the filter caps are rated for 35V. None of the other specs really matter since it doesn't use a switching power supply.

                          Comment

                          • altavek
                            Member
                            • Jun 2013
                            • 12
                            • USA

                            #14
                            Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                            Awesome, Thanks!

                            Comment

                            • ben7
                              Capaholic
                              • Jan 2011
                              • 4059
                              • USA

                              #15
                              Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                              You could use a diode with a lower Vf, therefore it isn't as likely to overheat.

                              Also, maybe a 1N5401 will be useful, it is rated at 3A instead of the 1.5A that the original is rated at.
                              Last edited by ben7; 06-08-2013, 05:43 AM.
                              Muh-soggy-knee

                              Comment

                              • altavek
                                Member
                                • Jun 2013
                                • 12
                                • USA

                                #16
                                Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                                Big ups Budm!

                                The new rectifier has my monitor up and running like a champ! Guess it's time to get back to work…
                                Attached Files

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #17
                                  Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                                  Great job, thanks for the feedback.
                                  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

                                  • Boh2k
                                    New Member
                                    • Jan 2017
                                    • 1
                                    • United States

                                    #18
                                    Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                                    Originally posted by altavek
                                    Sorry about that. Here's the inverter board from overhead.
                                    Hey New guy here looks like a great place electronic info! So on to what brought me here.

                                    I just was given a pair of rocket 5 g1 and one has (D110 & D108) busted!!
                                    What are these and where can i buy replacements for these?

                                    Thanks in advance!

                                    Comment

                                    • vinceroger69
                                      Badcaps Legend
                                      • Mar 2012
                                      • 6714
                                      • uk

                                      #19
                                      Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                                      can you upload a picture of the part? also has it any writing/number on it thanks

                                      Comment

                                      • Khron
                                        Badcaps Legend
                                        • Sep 2006
                                        • 1350
                                        • Finland

                                        #20
                                        Re: KRK Rokit 5 Gen 1 pops fuses as soon as it's powered on

                                        Might as well replace all four from that set. Going by their "fatness", they may well be some 3A diodes.

                                        If ordering from Digikey is ok, this looks like a good-enough and dirt-cheap option:
                                        http://www.digikey.fi/product-detail...4-3-ND/6022614
                                        Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                                        Comment

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