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Anyone know how to take apart a Roland Micro Cube?

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  • Anyone know how to take apart a Roland Micro Cube?

    I have a buddy who killed his Roland Micro Cube.

    The Micro Cube is the tiny 5 watt amp that Roland makes.

    The power input is a center post negative jack and he probably tried a center post positive (most common) adapter.

    I have all the screws removed and I have the small speaker removed. I can see inside the cabinet and I don't see any other attachment. It looks like it is friction fit in place.

    Anyone know how to get this thing apart?


  • #2
    From the back?



    • #3
      Sledge Hammer!


      • #4
        For those of you who don't know, I am a master in Zen Patience.

        I used all my knowledge and training (and a screwdriver) to pry it apart. LOL

        It was held together by a double stick foam around the 3 sides of the top plate.

        So, FYI if anyone searches later on. All you need to do is remove the 6 large screws on the back panel and pry the top panel loose. I can post a pic if anyone needs it.

        Now, I need a schematic. Probably not 100% necessary just to check the power circuit but I always like to have a schematic anyway.

        I'll let ya know how it comes out.
        Last edited by KapperDog; 10-12-08, 03:29 PM.


        • #5
          Just for reference, I found a great site with a ton of schematics...


          • #6
            Originally posted by KapperDog View Post
            Just for reference, I found a great site with a ton of schematics...

            VERY cool find! Bookmarked
            There's a great range of Moog schematics there, including the famous ladder VCF circuit


            • #7
              Originally posted by Michael Render View Post
              Sledge Hammer!
              ROFPMSL You're a funny man MR


              • #8
                Just an update: I had a few moments to do some diagnostics today.

                Oddly enough, it does not seem to be the power board. There are 4 boards inside.

                I traced through the power circuit and the diode and switch and all that seem to be fine.

                There are 2 TP's on the main board and they show Vdd and GND to be solid.

                The amp is a Texas Instruments TPA2000D1. I downloaded the datasheet on that and checked the Vdd/GND and I/O ports. Everything seemed to be clean.

                The CPU and DSP look to be Roland specific. One is stamped "ROLAND" and the other says, "BOSS". Isn't that a Roland trademark? I don't imagine there's much info on either of those.

                I'm not going to be able to do much more without a schematic. This $50 amp just isn't worth tracing this entire circuit. LOL

                If I find a schematic, I'll update this thread.


                • #9
                  Yes, Boss is a division of Roland. It was going to be MEG but they decided that didn't sound macho enough: http://en.wikipedia.org/wiki/Boss_Corporation

                  What are TPs?



                  • #10
                    TP's = Test Points. Used for QC and assorted other stuff during manufacture.

                    Here's picture of a PCB I've been playing with. You can see that all the capacitors and resistors are numbered (designated by a Cx or an Rx). CPU's, memory and other chips are designated by a Ux.

                    If you look next to the small gold pads you can see they are marked with TPx. These pads provide a contact point for the machinery used in manufacturing the chips to connect to the board and load code or test circuits.
                    Attached Files


                    • #11
                      Just in case anyone is curious what a cube looks like inside.
                      Attached Files


                      • #12
                        I wouldn't mind betting the amp chip is your culprit, especially given the supply is OK. 9 times out of 10, they are the cause of failure. They are generally fairly inexpensive and easy to replace if you have a solder sucker and some solder wick.

                        If you have another amp, you could do some signal tracing to find out if you have an audio input to the TPA chip. Connect a 0.1uF ceramic (or any other non polarised type) capacitor in series with the input to your tracing amp to avoid any DC getting into it in the event you accidentally touch a supply pin or a pin with a DC offset.
                        If you have a clean audio input and good supply voltages you can be almost certain the chip is at fault.


                        • #13
                          Thanks, I'll check into it.

                          There's only a couple other chips in the entire box. An op amp and a DA/AD converter being the most obvious.

                          The TI amp is only $2.36 so, I ordered a few. I'll update when they arrive.

                          Thanks again.


                          • #14
                            The output chip is only $2.36 or the op amp? If that is the price for the output chip, it is dirt cheap!


                            • #15
                              roland micro cube schematic no power

                              looking for a schematic datasheet
                              speaker checks out.
                              roland sucks they want 225 for a mainboard in an amp worth only 103 brand new. what a scam to keep you buying new only!
                              can someone take a pic of powerboard? or some volt readings for me?
                              i got corosion on L1 and c10. Can i replace c10 with what? and what to replace L1 with? Voltage readings would be great.
                              My c4 on power board is in question so much corosion is there a capictor supose to be there or not? Did it rot off? or just never one there?
                              thyristors on board? I can see two of them. Will try to test them and find out what kind. Voltage readings would be great!
                              Seems like this amp has negative pin for ac/dc adaptor if someone pluged in positive wtf is fryed? dont know if thats the case bought it broken to fix.
                              this amps so cheap and so digital its gona be hard fix.