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    Altec MX6021

    Hi All , greetings, someone pass a Altec Lansing MX6021 and I would like to learn how to repair it.

    The issue is there is no power to the speaker set.

    Note: Mods please move this post if you think it is in the wrong section.

    Upon inspection of the speaker power board, there were burnt components, of the resistors. the resistors were FUBAR.

    The power transistor seems to be shorted and I'm planning to replace those.

    The fuse is also open

    Normally for this caused? faulty filter capacitor? transistor? or shorts?


    As attached, it seems that some have gooey black stuffs on it.... i suppose glue become conductive?


    Many Thanks
    Attached Files

    #2
    Re: Altec MX6021

    Originally posted by ant3202 View Post
    Hi All , greetings, someone pass a Altec Lansing MX6021 and I would like to learn how to repair it.

    The issue is there is no power to the speaker set.

    Note: Mods please move this post if you think it is in the wrong section.

    Upon inspection of the speaker power board, there were burnt components, of the resistors. the resistors were FUBAR.

    The power transistor seems to be shorted and I'm planning to replace those.

    The fuse is also open

    Normally for this caused? faulty filter capacitor? transistor? or shorts?


    As attached, it seems that some have gooey black stuffs on it.... i suppose glue become conductive?


    Many Thanks
    Well, the first obvious thing I can see is an exploded SMD resistor.

    Nothing else looks too bad other than shit got really hot due to the glue being browned.

    You're going to need an SMD rework station and a schematic to repair this, you up for that? The rework station isn't expensive, 60$ will get you one that can do the job.
    Popcorn.

    Comment


      #3
      Re: Altec MX6021

      Hi Jazzie366

      thanks for the tips...

      You are right, the SMD has been burnt and i cannot read the values properly.
      Perhaps i need to ask people around and compare on it.

      Yea, i can lend a smd rework station from someone.

      Comment


        #4
        Re: Altec MX6021

        there are 5 smd resistors in parallel they should be all the same rating. I would change all 5 of them out.

        Comment


          #5
          Re: Altec MX6021

          Originally posted by CapLeaker View Post
          there are 5 smd resistors in parallel they should be all the same rating. I would change all 5 of them out.

          yea, CapLeaker, thanks for the tips, definitely it need to be changed.



          need help to identify... as it is badly burnt...
          i think it could be 1R0 but i might be wrong.
          Attached Files

          Comment


            #6
            Re: Altec MX6021

            OMG! SMPS in speakers and chloroprene glue on top of that! What crap is this?

            1R0 is likely, it is fusible resistor which acts as fuse when something goes wrong on the primary.
            Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

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              #7
              Re: Altec MX6021

              Originally posted by Behemot View Post
              OMG! SMPS in speakers and chloroprene glue on top of that! What crap is this?

              1R0 is likely, it is fusible resistor which acts as fuse when something goes wrong on the primary.
              thanks for your help Behemot

              you are right.... really crappy.... SMPS inside is really.... (
              older models were using transformer...

              can I say to change all to 1R0 ???

              i had checked.... the ic chip is busted, guess drawing too much current, burning the smd resistors and pcb 1.6A FUSE.

              as a precaution ... i will also change the filter capacitor and misc to better and reliable one.

              as checked with some tech guys ..... seems this board fails quite often.

              now no more decent stuffs from altec lansing...

              plantronics ... and stuffs are really going down......

              Comment


                #8
                Re: Altec MX6021

                You tell me, just got this BIG sub from Cambridge-whatever-something under Creative, expensive like hell, also SMPS in there (no wonder with the power the thing puts out) and ofc all caps busted. And vitually TONS of that chloroprene stuff EVERYWHERE.

                This is just crazy! Power supplies went ahead and even the El Cheapos start using two-forward topologies at least. But in audio equipment, everybody continues to produce the same shit they used to. Often even worse.

                When you start testing it, I suggest the lightbulb in series. Often it takes one bad SMD components to make the PWM driver explode again. This hould limit the current and protect it, plus you see right away there's a problem.
                Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

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                Comment


                  #9
                  Re: Altec MX6021

                  Those 4 resistors should all have the same value 1R0. Could you post a straight shot, high resolution pictures of the whole front and back side of the PSU? Right now, I'd say there are at least some resistors, the mosfet and the PWM blown. Once hi voltage gets shorted to the gate of the Mosfet, anything in between the Mosfet, including the PWM has to be checked. Only because there is resistance on a resistor, it doesn't mean the resistor is good. You would have to check the value of the resistor and compare it with spec. Usually resistors either burn up (open circuit) or they change their value of resistance HIGHER than spec. If you do up an order, get the PWM too. Probably only cost you an extra 1$ anyway. What is printed on U1?

                  Comment


                    #10
                    Re: Altec MX6021

                    Originally posted by CapLeaker View Post
                    Those 4 resistors should all have the same value 1R0. Could you post a straight shot, high resolution pictures of the whole front and back side of the PSU? Right now, I'd say there are at least some resistors, the mosfet and the PWM blown. Once hi voltage gets shorted to the gate of the Mosfet, anything in between the Mosfet, including the PWM has to be checked. Only because there is resistance on a resistor, it doesn't mean the resistor is good. You would have to check the value of the resistor and compare it with spec. Usually resistors either burn up (open circuit) or they change their value of resistance HIGHER than spec. If you do up an order, get the PWM too. Probably only cost you an extra 1$ anyway. What is printed on U1?
                    Hi CapLeaker

                    U1 is behind... i suspect it is blown too.
                    cannot see any wording on it like

                    Using a magnifying glass....
                    First Row: 03 510
                    Second Row: PA TM
                    Attached Files

                    Comment


                      #11
                      Re: Altec MX6021

                      Originally posted by Behemot View Post
                      You tell me, just got this BIG sub from Cambridge-whatever-something under Creative, expensive like hell, also SMPS in there (no wonder with the power the thing puts out) and ofc all caps busted. And vitually TONS of that chloroprene stuff EVERYWHERE.

                      This is just crazy! Power supplies went ahead and even the El Cheapos start using two-forward topologies at least. But in audio equipment, everybody continues to produce the same shit they used to. Often even worse.

                      When you start testing it, I suggest the lightbulb in series. Often it takes one bad SMD components to make the PWM driver explode again. This hould limit the current and protect it, plus you see right away there's a problem.
                      thanks for the tips....... light bulb trick is good.....pardon me as im still learning, directly replace the fuse with a light bulb to test in this case?

                      Comment


                        #12
                        Re: Altec MX6021



                        Some Component lists....
                        Attached Files

                        Comment


                          #13
                          Re: Altec MX6021

                          Originally posted by ant3202 View Post
                          thanks for the tips....... light bulb trick is good.....pardon me as im still learning, directly replace the fuse with a light bulb to test in this case?
                          You can rewire old lamp or just reconnect the socket to a power cord so it is in series with the device.
                          Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

                          Exclusive caps, meters and more!
                          Hardware Insights - power supply reviews and more!

                          Comment


                            #14
                            Re: Altec MX6021

                            I guess we are going to have a problem identifying / replacing U1. Maybe have to gamble on it still being good. I guess fuse F1 is blown too? also check those 3 pink resistors inside the heat shrink tubing.

                            Comment


                              #15
                              Re: Altec MX6021

                              Originally posted by Behemot View Post
                              You can rewire old lamp or just reconnect the socket to a power cord so it is in series with the device.
                              Alright, I will try.



                              Originally posted by CapLeaker View Post
                              I guess we are going to have a problem identifying / replacing U1. Maybe have to gamble on it still being good. I guess fuse F1 is blown too? also check those 3 pink resistors inside the heat shrink tubing.
                              Yep, the F1 has been blown out.



                              those resistors, four big ones..... i gotta take apart to check.
                              Attached Files
                              Last edited by ant3202; 02-20-2017, 07:05 PM.

                              Comment


                                #16
                                Re: Altec MX6021

                                Hello, ant3202. Did you fix your breakage?
                                I have the same problem. Even made new post on avsforum, but there is now answers.
                                Here is copy/paste.

                                I really need help with repairing my Altec Lansing MX6021. It has broken power supply. I have only basic knowledge of physics, a ability to solder, fan, a multimeter and the ability to buy components. After disassembling, I saw that the resistors were burnt (I managed to examine their 1R0 nominal), the capacitor that lost capacitance (a new 68uF 686 16x32mm 450V one was ordered), the punched out fuse T1.6A 1.6A 250V 382 (bought), and it looks like nothing more.
                                Yesterday I replaced all this and decided to connect without assembling. There was a BIG BADABUM! Resistors burned out again, the fuse too. The capacitor seems to be ok. It's good that I have spare parts and I can change them again. BUT. I'm a bad circuit engineer. But as I heard, maybe someone else has not been able to give proper power. I suggested that this is a power transistor. I tested it with a transistor tester . He showed resistance between the base 5 and 1 ohm. Apparently it's broken. Yesterday I ordered it. Now I'm afraid that I did not miss something else. But I do not know what and how to test. I searched the information on the Internet, but found nothing. No scheme, nothing. Only today I accidentally saw this topic and the person with the same problem as me https://www.badcaps.net/forum/showthread.php?t=60238 But the topic there is not closed. It seems that the person decided it. Could you express your opinion on what else and how to check? Or after the replacement of the transistor SPA08N80C3 (near R15) everything should be fine?
                                I really do not want to throw this stereo system out. This is a great system! You will not believe it, but I am satisfied with it just like the Elac FS 249.
                                Sorry for my bad English. I used google translate and my basic knowledge of English.
                                Best Regards.
                                Can You give any additional information about?

                                Comment


                                  #17
                                  Re: Altec MX6021

                                  Originally posted by zerbino View Post
                                  Can You give any additional information about?
                                  Hi zerbino,
                                  the first thing you should do is the incandescent light bulb trick, like this:
                                  https://www.badcaps.net/forum/showpo...4&postcount=70

                                  This will prevent your new parts from blowing up again when you have to test the power supply.

                                  Start by testing all parts on the primary with your multimeter. Any diodes or transistors that show low resistance (less than 300 Ohms) between any of their pins should be removed and checked out of circuit. Resistors should read same as labeled value or lower in circuit (higher resistance that what is printed on them is not good if above their tolerance).

                                  Last but not least, post pictures of your power supply board, even if it looks fairly identical to what ant3202 posted here. After all, there may be small difference in your power supply from his, so it helps for us to see what you are seeing to help you better.

                                  Comment


                                    #18
                                    Re: Altec MX6021

                                    Thank You very much for answer. when i'll get transistor, i 'll you lamp for insurance. If it will failed again, i'll let forum know. If I'll fix it, i will let know too.

                                    Comment


                                      #19
                                      Re: Altec MX6021

                                      If the transistor is shorted there is a big chance that the controller chip is also dead. Just something to keep in mind.
                                      Originally posted by PeteS in CA
                                      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                      A working TV? How boring!

                                      Comment


                                        #20
                                        Re: Altec MX6021

                                        Hello all!
                                        Recently i get transistor to change broken SPP08N80C3. As i understand transistor not original, but tested with transistor tester and soldered on pcb. Remember your advice to me i connected 100W lamp and googled how it works). As i understand, lamp must blink and shut down after power on BUT it always glows, so as i understand bord is short short-circuited. Only one ship U1 (1351D PCOI connected 1,3,4,5,7,8) not tested yet and i dont understand how can i test it. Tested only that pins do not call each other and 4 pin is GROUND. And test tested resistors (2W? 15mm length), its 157, 158, 1770, 1781 Ohms
                                        Attached Files
                                        Last edited by zerbino; 03-04-2018, 09:20 AM.

                                        Comment

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