The Repair Bench: Roland Micro Cube

| March 16, 2011 | 95 Comments

Learning how to troubleshoot electronic circuits is one of the handiest skills anyone can have if they are building or modifying amplifiers or effect pedals. At some point you’ll power-up a circuit and find that it doesn’t work, and then what? For this reason we write “The Repair Bench” section of Guitar Kit Builder about our own troubleshooting of amplifiers and other devices, to pass along to the reader the thought process, tips and techniques of troubleshooting electronic equipment.

In this edition of “The Repair Bench” we cover a common repair for us – replacing the input jack on a Roland Micro Cube amplifier. As we’ve mentioned before, when we’re not writing for Guitar Kit Builder we operate rock music schools where we use the Micro Cubes in some lesson rooms. With many lessons a days, and students plugging-in and out all day long, the input jacks on our amps take a beating. And let’s face it, kids are just not always as gentle on equipment as they could be. So on a pretty regular basis we need to replace the input jacks on all of our amps, including the Micro Cubes.

THE ROLAND MICRO CUBE

If you’re not familiar with the Micro Cube, it’s the small fry in Roland’s line of cube amplifiers. It’s an ultra-compact package that runs on batteries or from a 9 volt wall-transformer power supply otherwise used for effect pedals. Weighing in at just a few pounds, the Micro Cube comes with six digital signal processing (DSP) effects (chorus, flanger, phaser, tremolo and separate delay/reverb) and COSM® amp modeling.

COSM is composite object sound modeling, Roland’s proprietary amplifier modeling technology. Once a musical instrument generates sound vibrations, it reaches the human ear through various mediating objects, each of which significantly affects the sound. The material and configuration of the instrument, the electric/magnetic amplifying system, the air and the reverberation of the room all affect the final sound. Sound modeling, the latest DSP technology, “virtually” reconstructs these objects. Roland’s COSM uses the advantages of multiple modeling methods and succeeds in accurately emulating existing sounds, as well as producing sounds new sounds. Seven amplifiers are modeled in the Micro Cube:

  • Acoustic – a dynamic acoustic guitar sound from a standard electric guitar.
  • JC Clean – models Roland’s famous JC-120 Jazz Chorus guitar amplifier for a smooth, ultra-clean, ultra-flat sound. This is also a good choice if using an external effect.
  • Black Panel – models the classic Fender Twin Reverb tone, with rich lows and a bright high end.
  • Brit Combo – models the Vox AC-30TB, the rock amplifier that created the Liverpool sound of the 1960s. It produces a broad range of sounds, from clean to overdrive with increased distortion and greater power in the low-midrange when the Cube’s gain is boosted.
  • Classic Stack – models the sound and response of a Marshall JMP1987, well suited to classic and hard rock.
  • R-Fier Stack – models the super high-gain of the MESA/Boogie Rectifier amp, for slash metal, grunge and other lead tones.
  • Mic – used for when a microphone is connected.

INITIAL ASSESSMENT

This Micro Cube arrived on our bench with the input jack (Photo 1) pushed below the front panel and the gain control stuck and very difficult to turn.

Photo 1 – Micro Cube with Input Jack Pushed Below Front Panel

It appears that at some point the nut for the input jack became loose and eventually fell off. This is a chronic problem with the plastic jacks and nuts used in many modern amplifiers. In this case the amp continued to be used, which eventually pushed the jack inward until it stopped working.

OPENING THE MICRO CUBE

Opening the Micro Cube is pretty straightforward, but we’ll mention one tip here. Since we’re frequently repairing more than one amplifier at a time, usually because we’re waiting for parts to arrive, it’s important to keep all of the parts for one amp together, but separated from the parts for other amps. A simple Ziploc type bag that can be labeled comes in very handy here.

Photo 2 – Keep All Parts Together and Labeled in a Plastic Bag

As to opening the Micro Cube, remove the screws on top and for the plastic bezel, and the larger screws around the perimeter of the back. Next, remove the plastic bezel and lift the amp chassis (Photo 3) out of the cabinet, stopping just before the speaker wires get tight. At that point you’ll need to reach in through the opening and gently remove the connectors from the speaker. Then completely separate the chassis from the cabinet.

Photo 3 – Amp Chassis Lifted Enough to Detach Speaker Wires

TROUBLESHOOTING

There are two small printed circuit boards (PCBs) attached to the control panel (Photo 4). One holds the input jack, gain and volume controls. The other holds the amplifier modeling switch.

Photo 4 – Internal View of Printed Circuit Boards

In our amp, when the input jack was pushed in below the front panel, it caused the gain control potentiometer (pot) to be pulled apart (Photo 5), since the pot shaft is attached to the panel while the body is attached to the PCB.

Photo 5 – Gain Control Pot with Missing Shaft

So the first need we identified was to either fix or replace the potentiometer. After inspecting the shaft and the potentiometer (Photo 6) we realized that they could be re-mated by aligning the guide posts.

Photo 6 – Potentiometer Without Shaft, Showing Guide Holes

After playing with it awhile we were able to get it to seat perfectly (Photo 7) and used needle nose pliers to fold the tabs back in place for attachment.

Photo 7 – Control Shaft Reseated On Potentiometer

Usually when these amps come in for repair the input jack is physically damaged (Photo 8). In this case the jack looked fine, but since we had the chassis open already we decided to replace it with a new one. Our de-soldering tool (shown at right), an inexpensive purchase from Radio Shack, comes in very handy for replacing jacks. This tool has a soldering tip with a small hole in the center of it. The hole is attached to a tube with a rubber bulb at the end of it. To use it you squeeze and hold the rubber bulb while applying the tip to the solder pad. When the solder turns liquid you release the bulb and the solder is sucked up through the tube. You then hold the tip over a suitable area to release the captured solder (not the printed circuit board!) and squeeze the bulb again to blow it clear. We find this tool to be very effective and a real time saver for removing jacks from printed circuit boards.

By the way, the input jacks used in the Micro Cube are made by Jalco, but the only source we found for them is from Roland. You can contact Roland support at http://www.rolandus.com/support/ or call (323) 890-3740. Parts can be ordered by telephone with a credit card. The jack sold by Roland does not come with the nut, so order it as a separate item. It is not a standard size nut, so make sure you have the right one already or order a new one.

Photo 8 – Input Jacks Are Frequently Split Open When Damaged

The underside of the PCB (Photo 9) shows the four pads to be de-soldered for jack removal.

Photo 9 – Solder Pads for Input Jack

With the old jack removed, installation of the new jack is a simple matter of inserting the pins into the PCB and re-soldering. With the jack installed (Photo 10) we can re-attach the controls and jack to the control panel.

Photo 10 – New Jack Installed on PCB

After testing the amp to make sure it is operating normally we just reverse our process of opening the amp, being sure to re-attach the speaker wires and tightening all of the screws.

Photo 11 – Input Jack Attached to Control Panel

This type of repair is about as simple as it gets, but it covers a number of important points:

  • Organized – keep parts together and organized with aids such as a clearly labeled plastic bag
  • Resourceful – some parts can be repaired without buying a new one, such as the broken potentiometer in this amp.
  • Parts – the manufacturer is often a good start when trying to find replacement parts. Some makers provide much better support than others, and supply houses are the best alternative to an unhelpful manufacturer.
  • Tools – Some specialty tools, such as the desoldering iron, are invaluable to making the job faster and easier.

Have a question about repairing your Micro Cube? Feel free to post a comment here and we’ll do our best to help.

Category: Kit Building 101, The Repair Bench

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  1. avatar fisherdennis says:

    My Roland Micro Cube, hardly used and just off warranty will make no sound, except for the “A” tuner sound. So I figure the speaker is ok and connected, getting power, etc. The in jack seems like new. I am not skilled in electronics but do have an electrical meter and can use that. Any hope? or is this a goner?

    Thanks for any help I can get.

  2. avatar guitarkitbuilder says:

    Dennis,

    First I’m assuming that you’ve tried the sound across all the settings and controls and are getting nothing. The fact that you are getting the tuner sound suggests that much of the amp is working, but perhaps just not the input section, and perhaps just not the input jack. Have you tried the auxiliary input jacks on the back? Try feeding an iPod or similar signal in there and see if you get sound, and let me know. Does the input jack for the guitar seem loose? With a jack inserted and a little rotational pressure applied does anything change – any brief sound, scratchiness, clicks, pops, etc? I doubt that the amp is a goner.

    Jeff

    • avatar Michael Gury says:

      Hi Jeff,

      Something really odd is going on with my Micro Cube: when I plug the M-cube power adapter cord into the back of the amp, the amp won’t turn on when I hit the on/off switch. But when I pull it out and hit the on/off switch, the light goes on and the batteries are powering the amp, which sounds just fine. So I’m kind of mystified. This just happened. Absolutely no changes have been made or damage done since the other day when I was using the amp. I haven’t plugged this into some British 220 main. I’ve plugged the thing into two or three different sockets and still no power to the amp. Did my Roland AC Adaptor ACR-120, model D9500, die?

      Thanks!

      Michael

    • avatar Matt says:

      Hi Jeff,
      I have a very similar problem as I my input jack went down I opened it to pull it up.now the aux. works fine and I can listen to the music fine but the input jack does not seem to work.at max vol.i can hear some faded sound of my guitar when playing other than that the guitar input seems dead.i too have a electric meter but just don’t know whAt to do.i did get a little earthing once when I was putting back the cover on one time then I tighted the earthing wire in the box and it was gone.

      Please lt me know what to do .thanks
      Matt

  3. avatar Forest90 says:

    HI, I got this micro cube a few weeks ago that a renter left behind when they moved and I was wondering if you can help me find out whats wrong with it or at least point me in the right direction. I got it home and set it up to play but the thing doesn’t turn on. I looked inside and the only problems I had were that the input jack was pushed in and the gain pot came off. I fixed both of those problems, but it still doesn’t work. I don’t see anything obviously wrong with it from just looking. So I was wondering what should I look at or check first? to maybe find the problem. I think that its a lost cause but it would be awesome if I could get it working.

    Thank you.

  4. avatar guitarkitbuilder says:

    Forest,

    It sounds like your amp was in a similar condition to the one we repaired, with the jack pushed in and the potentiometer separated. How did you repair the jack? Did you replace it? Can you send us some clear photos of the input board so we can see what’s happening?

  5. avatar Tjjmaxd says:

    Hey guys!

    My Roland micro cube has gotta be my favourite amp that I can practice on and I fell in love with it the minute I plugged it in and jacked it up, but ivd got a serious problem. The other day I accidentally used a different power adapter on it than the one it says for you to use. Now it worked perfectly, sounded exactly the same no problem at all, but now when I try and plug it in with the original adapter it won’t seem to work anymore. I can’t get a blip out of it, nothing works on it 🙁 it may also have been that I forgot to turn it off, as the power switch was on when I went back to it. I’m really not sure, but I really wanna get it back in working order somehow, I love that little amp!
    Please help
    Thanks

  6. avatar guitarkitbuilder says:

    TJ,

    The first question is what was the voltage and polarity of the power supply (PS) you accidentally used? It should be marked on the body of the power supply, and there should be a small illustration of the polarity, showing either + or – as the center. Let me know what you find on this.

    Now as to why the original PS isn’t working anymore, I’m just guessing here, but I’m wondering if the second PS connector was of a larger size, and perhaps stretched out the inside of the power jack on the amp, so that the original PS doesn’t make contact anymore? Are the power connectors from the two supplies identical in size?

  7. avatar Tjjmaxd says:

    Thanks for the help!
    Ok so the adapter was a nine volt, I’m pretty sure it was + .
    As for the size of the connector I’m not sure but I think they’re about the same size, one might be slightly larger than the other but the difference is hardly noticeable, in any case, is there anything that I can do to save my little buddy?
    And thanks once again

  8. avatar Doc says:

    Hi crew,
    Know you are featuring work on the micro but wonder if you would have a thought re a problem I’m having with the cosm swithch on my Roland Cube 80XL. The switch doubles as a tuner which works just fine, but after a bumpy ride to a gig, the amp model stays on the same amp in all positions (seems to be stuck on black panel). No outer evidence of any damage and I have only had the amp for a few months.
    Any suggestions would be helpful as I am not able to get the amp in for service with Roland.
    Thanks,
    Doc

  9. avatar guitarkitbuilder says:

    I’m happy to try to help diagnose the problem but I need some clarification. How do you know you’re having a problem with the COSM switch? I have the owner’s manual in front of me and there is a Tuner switch, a “Select” switch, and the rotary knob for the different COSM sounds. The select switch changes between the clean lead channel and the COSM effects I believe. I think you’re saying that the tuner switch is working. What happens with the select switch – does it change between the clean lead and the COSM effects (which I understand you to say are stuck on Black Panel)? With the tuner on, try the manual tuning mode – does the rotary knob work in terms of changing the string being tuned?

    Couple of other things – make sure there is no footswitch plugged in, since this interacts with the rotary knob setting. Also, do a factory reset to make sure that the solo feature is not getting in the way. To do the factory reset, Hold down the [TAP/STOP] switch and the SOLO [ON/OFF] switch at the same time and switch on the power. The SOLO indicator blinks and the settings saved with the SOLO function are returned to their factory defaults.

    OK let me know what you find

  10. avatar Mrjones2004x says:

    Hi there, hopefully you can help me out.
    Had a micro cube for about 6 months with no grief and loved it. Decided to wire in an external speaker jack to see how it sounds. I first off wired in a switched mono jack and mounted it the rear panel. This didn’t work as I soon realised I was shorting out the amp with the negative speaker wire on the chassis.
    And how I took it out and fitted a plastic mono speaker jack and it worked fine for about 30 mins through the internal speaker then the next time I tried to use it was dead. Had an 8 ohm cab plugged in for 5 mins at one stage but as I say was working fine before turning off.
    Checked all my solder connections and also put back to standard even to test. Power comes in and go’s to the main board but I don’t know how to check after that. Only used proper psu and with batteries.
    You think I fried something by shorting it out? I prob did it about 10 times during the first install whilst scratching my head. I love this amp so hopefully you can help me
    Regards

  11. avatar Mrjones2004x says:

    Hi there, hopefully you can help me out.
    Had a micro cube for about 6 months with no grief and loved it. Decided to wire in an external speaker jack to see how it sounds. I first off wired in a switched mono jack and mounted it the rear panel. This didn’t work as I soon realised I was shorting out the amp with the negative speaker wire on the chassis.
    And how I took it out and fitted a plastic mono speaker jack and it worked fine for about 30 mins through the internal speaker then the next time I tried to use it was dead. Had an 8 ohm cab plugged in for 5 mins at one stage but as I say was working fine before turning off.
    Checked all my solder connections and also put back to standard even to test. Power comes in and go’s to the main board but I don’t know how to check after that. Only used proper psu and with batteries.
    You think I fried something by shorting it out? I prob did it about 10 times during the first install whilst scratching my head. I love this amp so hopefully you can help me
    Regards

  12. avatar miguel says:

    Maybe u cam help I bought the micro cube with my last check at a dealership I worked at before it closed down and when I ended up homeless I decided id make the thing smaller becaise it was hard to carry I gutted it replaced the speakers with 2 computer speakers that were a bit smaller than the first but had better bass response and stuck em in a little ghetto rigged speaker box (like the old stereos had) well I fit all the parts in there and it all worked for about a year ivleft the frankencube in my car for like two Weeks and now it wont light up or make a sound is it doomed??? Please help me out if you can because I love that thing we beem through hell and back

  13. avatar Paul says:

    I have an older Micro Cube, 2006 I think. It is a great little amp but lately I have noticed a decrease in volume over an increasing number of models. The acoustic was quiet from new and I believe that is just the nature of the beast. Over the last couple of years the quietness has migrated to the JC clean, black panel and Brit combo. Turned to classic stack and the volume goes up. I play steel guitar and I need clean or 2nd choice of black panel. The amp has been well used but not abused. Is it just getting tired or is there something going wrong? Any help would be greatly appreciated. Thanks

    • We have not seen this type of problem before. How much of a volume change is happening? Is the change “just noticeable” or is it down to the point where you would say that the amp only plays very softly for those particular modeling positions? The only thing we can think of to try is to clean the rotary switch that selects the different amp models. You could open up the amp and use some contact cleaner on the switch. Deoxit is one brand to try. If you haven’t used contact cleaner before let us know and we’ll describe the procedure, but it’s basically spray and rotate through the switch positions.

  14. avatar Paul says:

    Thanks for your reply Jeff. Yes it is a marked difference when it gets to classic stack, at least 30% louder. It has been a progressive thing, so your suggestion is probably a good one. I have Nu-Trol control cleaner which has worked well on pots in the past. I’ll try it tomorrow. Thanks very very much!
    Paul

  15. avatar Paul says:

    Well, Nu-Trol helped bring the Brit-Combo up somewhat, but not to the same volume level as the classic or rfier. Black panel and JC clean are unchanged. I’ll see if I can find a different cleaner. One thing I did notice is that when rotating the switch that there is a tiny ,and I mean tiny ,difference in resistance when turning the switch counter clockwise thru BP and JCC. No difference going clockwise. I am in Canada so Roland parts are probably hard to come by.

  16. Paul, since it made SOME difference it suggests that the switch is the problem. You can contact Roland USA to buy parts. I haven’t had a chance to open up a cube and look at the switch since you wrote about this problem – is the switch open so that you can see the contacts, or is it closed?

  17. avatar Paul says:

    Jeff, I phoned Roland in Vancouver, they too had not heard of this problem before. According to the tech, the cosm switch has nothing to do with volume control. It simply sends a signal to the computer as to what model is selected and the computer takes care of the rest. At first I think they didn’t believe me ,so I hooked it up to a guitar using 1/2 volume settings on guitar and amp , no gain or other efx and tone at 1/2 on both, I picked the same string thru all the models and when it was done he agreed that there is a problem. The switch is sealed except at one spot where a rod comes out and contacts a flat metal strip. He said there is step up in signal at classic stack but he described what this amp does as a”leap”. He had no idea why there was slight increase in the Brit model after it was sprayed but he did say that the volume is still too low on it.
    His suggestion was to send it down to Vancouver, but agreed that the freight and cost of fixing it would be prohibitive . I live 1600 kilometres from Van. I’m going to keep using it and just give some gain when needed until it craters.
    Thanks for your help tho. I’ll keep you posted as to how it progresses.
    Paul

  18. avatar Tony Wardle says:

    Jeff, please can you help. I have just acquired a used Cube 30. All’s generally good, but turning the Delay/Reverb knob does not appear to work. Everything else (EFX etc) is ok, though like above I get a noticeable increase in volume when turing from Black Panel to Brit Combo. Is there anything I can test or try before I take it for repair. Thanks, I appreciate any help. Tony from the UK.

  19. Tony, I don’t know that all of the amplifier models SHOULD be the same volume so I’m going to skip that one for now. If I understand you correctly, you’re not getting any delay or reverb at all. If that’s the case I would want to first check that the delay/reverb control is working and connected. I don’t have a schematic for this amp but my guess is that the delay/reverb control is a potentiometer that connects to a printed circuit board via a ribbon cable. I would inspect the pot and cable carefully to see if any of the connections are broken/bad/disconnected. If you are comfortable with some troubleshooting, I suggest you open up the cabinet and check the connections to the delay/reverb control at both the control side and the PC board side. See if gently flexing the connecting cable changes anything (makes the delay/reverb work briefly). If you have a digital multimeter you could measure the potentiomter’s resistance (with power off on the roland) at the potentiometer and at the PC board to make sure the connections are good. Let me know what you find, or if you need more guidance on how to do this. Good luck.

    • avatar Tony Wardle says:

      Jeff, I had a good look around inside, as you suggested. Nothing appears loose… and as I don’t have a potentiometer I can’t comment on the connections. Therefore the delay/reverb issue is as before. So, outside of any more ideas, the amp will be on it’s way to the repair shop in the next week or so…. or I may just live with it. Thanks for your help… I really appreciate it. Cheers Tony

      • Tony, sorry to not be clearer. The delay/reverb control IS a potentiometer (variable resistor). If it’s not having any effect, I would visually check the connections/wires that go to it, and/or its connections to the printed circuit board.

        • avatar Tony Wardle says:

          Jeff. thanks again for the reply. Sorry for my ignorance re. control/potentiometer. I have checked the connections to and from the control to the circuit board once again… and all appears fine. I think I will take it to the repair shop here in the UK and let them have a look. Thanks again Cheers Tony

  20. avatar Paul says:

    I can help on the volume for the models. The acoustic setting is the lowest volume, it should step up noticeably for JC Clean and Black Panel. Those 2 should be pretty much the same level. Brit Combo should be louder by as much or slightly more than the difference between acoustic and JC . Classic Stack and R-fier should be considerably louder than Brit Combo. The explanation I got was that the Brit, Classic and R-fier have more gain programmed into the models.
    Jeff ,I took a road trip over the weekend, stopped over nite in a city that conveniently had a Roland dealer. I was buying some strings and pots, and got talking to the tech there about my amp, he told me to bring it in, cause he had never heard of that problem before. I turned it on, plugged in my guitar and damned if it wasn’t back to normal. A little embarrassing to say the least! We plugged into a new micro cube (same model) and they was no difference between the 2 amps. It took me some time to convince him that I wasn’t a nut job and that I actually had that problem.
    My guess is that something had worked itself loose initially and the vibration from riding on the floor of my truck for 8 hrs reattached it. I am going to follow the advice that you have given Tony and check any and all connections in the amp .

  21. avatar Paul says:

    Jeff, when I initially turned it on at the store and discovered that it was working properly, it was on battery power. When we did the comparison he used the adaptor for the amp that we compared mine to. It is unsettling , I haven’t had the opportunity to take the amp apart yet but will try to get to it this week. I check it every time I turn it on, gun shy would be the term used.

  22. avatar Niall says:

    I managed to break the input jack on my Microcube by dropping a Strat on it. Can anybody tell me the Jalco part number so that I can get a replacement?

  23. Niall, you won’t need the part number. Just contact Roland using the info in the article and tell them which amp you have. And don’t forget to order the nut if needed, since it’s sold separately from the jack.

  24. avatar Henry Harvey says:

    I have a Roland Bass Cube RX with the COSM function not working. Everything else works just no COSM selection. What do I need to do and is there a factory reset?

  25. avatar Mick says:

    Hello
    I am looking for some advice. My MicroCube had a very irritating rasp with any input. Even the built in tuning fork had the rasp. So I opened it to start looking for bad connections as a first guess. My first action was to put my oscilloscope probe across the 9v input (I had checked the power adapter before opening.) now the amp is completely silent no output for any type of input. I would guess I blew a fuse but the Red LED power light is still lit up. Any suggestions? Did I err in using a 10pF scope probe?

    Does you know where I might find a schematic so I can dig a little deeper.

    Thanks
    MSOB

  26. avatar Florent says:

    Hello, I have a micro cube and recently button reverb / delay is inactive and no longer works … The reverb is still up when I turn on the amp … It is repairable? Thank you for your advice (sorry for the mistakes, I’m french)

  27. avatar Trevor says:

    Hi Jeff
    My Roland Cube 20XL bass amp stopped working suddenly last week. Now, when I turn it on the lights come on briefly then go out, apart from the mains light. No sound apart from a speaker click When I turn it off, the lights come back on briefly.
    I haven’t opened it up yet as I don’t know what to look for. However, I have my screwdriver to hand if you have any suggestions.
    Many thanks for any advice you can offer. TH

  28. avatar Trevor says:

    Hi.
    Re my previous post, I took the amp apart (the double sided tape was tricky) and checked the connections and fuse. Everything seemed ok so I put it back together. Hey presto! All is now well with the world. A bit worrying as I don’t know the cause but at least It’s working again.

  29. avatar Adrian says:

    Hi Jeff,
    I’ve run into a problem with my Micro Cube. It appears that it’s now permanently stuck in what seems to be JC Clean mode. The amp model switch doesn’t appear to be working, and no amount of vigorous knob turning helped. Would you happen to have any insight into this? Thanks in advance.

    • avatar Wim says:

      Hi Jeff,
      The ‘amp model switch’ of mine Micro Cube RX stop working and no amount of vigorous knob turning helped. Same problem asAdrian. Do you have any idea what the problem could be or how to fix this?
      Thanks,
      Wim

      • avatar Martyboyo says:

        Hi Jeff,

        I see a few people have the same problem as me with the ineffective COSM switch on my Micro Cube. It appears that it’s now permanently stuck in what seems to be JC Clean mode. The amp model switch doesn’t appear to be working, and no amount of vigorous knob turning helped. Has anyone come up with any kind of solution yet ?? Thanks

  30. avatar John Harding says:

    I also have a microcube that is stuck in JC clean the cosm amplifier switch has no affect whatsoever.

  31. avatar Scott G. says:

    Jeff,

    Both my own and a friend’s Rowland Microcubes only work when plugged in, but not on even new batteries. I cleaned the battery contacts. They did not seem to need it. What should I try next?

    Thank you for your time.

    Scott G.

  32. avatar marty says:

    I have a broken power switch.The piece you push in broke off so I have to use a pencil to push it in and turn it on/off. Is the switch attached directly to a PCB? Is it easy to replace?

  33. avatar marty says:

    Oh, and thats on a micro cube.

  34. avatar marty says:

    micro cube 2watt that is

  35. avatar Liz Williams says:

    Hi Jeff – Thanks for taking questions about the microcube. Mine is having the same problem Paul’s did: Today it suddenly got very quiet on the acoustic, JC clean and black panel settings. While I’ve been looking on the internet, it’smigrated to the brit combo setting as well. Classic stack and Rifier still scream. I’ve tried battery power and AC (and yes, it’s 9volt and the tip and jacket polarities match), and there is no change. It was in fine form yesterday, and today, it just wimped out.

    If I turn the volume to 10 and the gain to 5, I can get enough volume, but it won’t give the clean tone I’m looking for and volume. It’s as though the volume has a governor switch on it, but only on certain am modeling settings. Bizarre.

  36. avatar Tellef Ogrim says:

    Hi Jeff, I use my Micro Tube a lot but lately the amp switch stopped working. The amp stays on the clean sound regardless of the amp model I chose. Should I open the cabinet and soak the amp switch in contact solution (spray?)

  37. avatar Jennifer says:

    I have a Micro Cube and just acquired a Cube 30x recently. I love them both. While I’m playing the 30x, the efx will change all by themselves. I tightened both efx knobs and it doesn’t do it as often, but still does when it so chooses. Do I have a bad pot or can I do something else to fix this? Any advise would be appreciated.
    Thanks, Jennifer

  38. avatar Mark says:

    My Micro Cube amp does not seem to work at all, with the supplied DC adapter, and just with Alkaline batteries. When I opened up the amp, everything seemed connected up, but I didn’t mess around too much, so I put it back together, do you know why I can’t get my amp to actually turn on? Any advice would be really helpful, thanks in advance!

  39. avatar tellef says:

    hi, the amp modelling in my micro cube stopped working. i feel (!) it could be the switch but how can i confirm that??
    best
    tellef
    oslo

  40. avatar Pete says:

    Hello all,
    What a great site this is; I just stumbled onto it tonight. I have a Roland Cube 30 (not 30X) with the exact same problem as Liz Williams MicroCube (21May14). Suddenly very quiet on 3 amp settings: JC Clean, Acoustic, Black Panel. Still “screams” on Brit Combo, Tweed, Classic Stack, Metal and R-Fier. E-mailed Roland, response was “no user-serviceable parts inside. Send it in, or take to an authorized repair center.” Probably cost-prohibitive, as a new Cube-40 can be had for $250. So obviously this problem is common on COSM modeling Roland Amps. Any ideas?

  41. avatar Lorenzo says:

    Hi Jeff, I have a problem with my microcube, it won’t sound at all even the tuning fork is totally muted. If I plug an external audio source into the AUX IN jack, the amp works correctly. moving the rotary switch I can also hear some pops. Any idea what the problem may be? Is the processor blown up, perhaps?

  42. avatar Andy L says:

    Hi, my cube is working fine when i use batteries but there’s no power when I use the mains lead. Any ideas? Cheers. Andy

  43. avatar Gary says:

    Howdy. I’ve done a bit of modding with a standard Micro Cube, but I also have the Bass Micro Cube RX which is stereo just like the guitar RX Micro Cube. There are 2 pairs of 8 ohm speakers in parallel, so each output of the amp is 4 ohm. My question is: Is this amp bridgeable, so that I could wire the outputs to drive a single 8 ohm speaker ? I’ve wired one side to an 8″, 4 ohm woofer and it sounds much better. I could just use 2 of those in a separate cab driven by the RX in stereo, but I figure with a single 8 ohm speaker I’d get more power by bridging… and only have to use a single speaker. BTW – my original Micro Cube is driving a 15″ antique Jensen guitar speaker, and it sounds dynamite. Thanks for all info.

  44. avatar matt says:

    Hi there.
    I’ve recently had an issue with my microcube. It works fine when running off the adaptor but won’t switch on when I try to run it off batteries.Any help?

  45. avatar EL says:

    Hi, my Micro Cube is also stuck in JC clean, it stood for a few months, then when I switched it on the COSM switch had no effect. Was this solved? Thanks

  46. avatar Andy Hills says:

    Hi, I have a similar problem on a Bass Cube 100. Sometimes only 2 of the COSM models can be selected. The other positions produce no sound and a nasty DC thump if you turn the amp on with the non working ones selected. If I leave the amp switched off for a while sometimes the problem goes away and then comes back again at the next switch on.

    The selector switch selects a voltage from a resistor divider network and feeds it to an IC on the main board. I am pretty sure there is no problem with the switch and I have resoldered all of the resistors etc.

    I am thinking that this could be a firmware problem that Roland aren’t telling us about. I’m reluctant to pay a big charge for Roland to sort this out if it is a design issue. Anyone else got this problem?

  47. avatar Derek says:

    Hey guys I’m hoping you can help me,I’ve got a cube 30 bass amp ,I’m currently having some problems with it, when I play through it it sounds like it distorted no matter what the settings are, even in low gain ,it should be a clean sound but it’s constantly distorted any ideas ,any help would be welcomed please as I really love this amp and would love to have it back to normal!

  48. avatar Bridget says:

    Hi Jeff, I have the same problem as Andy L, Mark. I used batteries in my amp for the first time a few months ago. Yesterday I went to use the cube with the AC Adaptor but it won’t work now (it worked fine before). I thought it might be because I’d left the batteries in, but when I took them out it still wouldn’t work. How can I test the adaptor to see if it’s working or should I just buy a new one? Thanks for your help!

  49. avatar Blues says:

    Hey there!

    I just got that old 2007 or 2008 Micro Cube out from under my bed and was trying to play again (which I have done very very little in the past 3 or 4 years). I have the same problem already described multiple times here.
    I can’t change the different amp modes anymore. When I turn the knob, nothing changes and it all sounds like BRIT COMBO (if I remember that correctly, it’s been a while since I last played) which should be the mode it was still set to when I put it under the bed last time.

    Anyone figured that out already?

    • avatar Blues says:

      Nobody?

    • avatar Blues says:

      Figured it out. There was something broken inside that amp mode rotary switch. A little kinda “fork thingy” that connects different spots/pins when you turn the knob. I just desoldered the switch and replaced it with a new one, Micro Cube is working again!

      • avatar CubeBlues says:

        Hi I have a Micro Cube RX also stuck on the brit combo setting also. I have the amp apart now and testing the switch with a multi meter indicates that the switch is faulty. So im now wondering where “Blues” who posted on March 10 got the replacement rotary switch from? Any website links or help would be greatly appreciated Thanks rock on…

        • avatar CubeBlues says:

          Blues is right ! Now my Micro Cube RX is working again ! .. Spare parts at Roland Australia supplied a 8 position rotary switch for my RX micro cube, the part number is SD000907 for $9. Just desolder the old switch and replace. Its worth doing if your handy with a soldering iron. All the best with your cube blues… oh and thanks “Blues” nice post!

  50. avatar trickycube says:

    Nice post. I was checking constantly this blog and I’m inspired!

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  51. avatar Jeff the plumber says:

    My Micro, which has always worked great, is having issues. First off, power supply failed. Tried another one, close match to the 9v/500ma spec’d out. Doesn’t work. doesn’t even turn the light on. Tried 6 fresh AA batteries – everything came on, it seems – the aux in was nice and loud. Tried guitar – no joy – it’s at about 5-10% of usual volume. I can hardly hear it with or without the aux in going. Dug around and found another supply rated 12v/700ma and it just gets hot – very hot. Micro does not power up. I can understand it’s having internal/external power issues, but shouldn’t it work ok on batteries for crying out loud?

    It has before – lots of times.

    I’m about ready to drag my Roland 405 mini-stack out of the garage.

    Thanks in advance.

  52. avatar Blues says:

    Okay guys, figured it out. All you have to do is change that rotary switch thing (part no. 5100026060 – you gotta do 12 solder joints, 10 small pins connected to the circuit board and 2 thick ones just to keep it in place) – it’s 11,40€ in Germany (5,50€ for the part + 5,90€ for the shipping), sent to you directly from the Roland Company.

    What had happened to my switch is quite simple.. The middle black part you can turn is made of plastic. It has a little metal Y bracket attached to it. When turning, the bracket connects different pins of the switch, resulting in different resistance values (using/combining the external resistors on the circuit board). Unfortunately, the mounting point broke (it’s just 2 tiny plastic pins) and the little Y bracket fell of, not moving at all anymore.

    In the following pictures you can see the problem:

    The little bracket is just lying around..
    http://abload.de/img/dsc_0423_bearbazosu.jpg

    Picked it out
    http://abload.de/img/dsc_0425_bearbb4pb5.jpg

    Here, I highlighted the spot where the 2 broken plastic pins were before.
    http://abload.de/img/dsc_0424_bearbmsq9t.jpg

    The circuit board with the COSM switch is 59€ btw, if anyone thinks it would be easier to change the whole thing (like I first thought) so you only have to do 3 solder joints..

  53. avatar Luis says:

    Does someone knows how to reset Roland Cube 30x amplifier?
    Thans a lot
    Luis

  54. avatar Bas Vossen says:

    trying to find a schematic diagram for a roland microcube N225

    found a virus posing as a zipped ‘roland diagram’

    kids blew it up at a jamsession, now it’s not coming on anymore. Checked the power switch (ok) and fuse (was blown), tried with batteries and external power.

    • avatar Al says:

      Hi,
      I am looking at buying a Roland Cube 20XL bass amp but this does not have an XLR output jack. I was wondering if it would be possible to add a DI box internally but connected to the main amp input so that adjusting the volume control does not affect the feed to the desk.
      Any thoughts?
      Thanks

  55. avatar Paul says:

    When I plug in my Roland N225 and turn it on, the red light doesn’t come on. Took it apart and did some probing with my DMM and found that the high side of the ON/OFF switch has power (7+Volts) when in the OFF position but shorts to ground when in the ON position. I checked the impedance of the other pole of the switch (downstream) to ground while in the OFF position and sure enough there’s a short to ground. I need to replace the ON/OFF switch, but can’t find a schematic that will tell me the part #. Help!

    Thanks in advance,

    Paul

  56. avatar Trevor says:

    Hi I have a Roland cube the little red light beside the ‘a’tuner button flickers and the input plug does not seem to work at all, if I plug in through the aux socket it works but no volume control or reverb etc , any solutions would be great , I’m a novice but I have took it apart and all looks OK , thanks Trevor

  57. avatar jonathan says:

    I recently purchased a roland street cube. It worked great for 2 months. Then, suddenly, it drains the AA batteries within 5 minutes. Ive used several sets of batteries, different types. Any ideas?

  58. avatar Justin says:

    Hi, I don’t see anyone else who has posted this problem. I’m not sure this page is still active or if the person that wrote the article is still around to answer questions… But my MC headphones/rec out doesn’t work in fact it never has from the day I bought it brand new.. I never bothered to bring it back because at the time I never used the out jack anyway.

    Can anyone help me with this? Everything is working fine and I’ve never dropped it, spilled anything on it or damaged it in any way. I just want to use this for a headphone practice amp. But if it’s going to take a ton of time or needs replacing parts then maybe it’s not worth it??
    Any help would be much appreciated.. Thanks in advance!
    -Justin

  59. avatar John Myles says:

    My son says he plugged in a wrong adapter to by precious cube street. It will not go on with batteries or the proper adapter. Is there a fuse or a circuit protection in this or is it ruined?

  60. Very rapidly this web site will be famous amid all blogging people, due to it’s nice content

  61. avatar REC says:

    Does anyone have a schematic with the parts list for the Micro Cube N225?

  62. avatar ron bongarts says:

    Hi, My KC500 has hissing from the high freq horn witch I replaced the diaphragm in. Is there an “easy” fix for this that wouldn’t cost that much? I’ve read a lot of KC500’s have this problem. I know this forum is on micro cubes but I could use the advice very much. I have no clue how to work on circuit boards but wish I did. A speaker tech I wrote to said I could order the whole pcb for $200.00 but that’s way more than I’m gonna spend on this old amp (if I even knew how to switch out the boards). Thanks a lot. Ron Bongarts …Sacramento Ca.

  63. avatar Dennis says:

    hi, my micro cube speaker is not playing. when i plug it to headphones all is working ok. I have tried connecting 3 different speakers.

  64. avatar romain05 says:

    hi, I’m going to replace jack “Jalco” but impossible to find the part on the web typing “jalco m3” or other type “jakc female micro cube roland”…., could you help me please ?

    with best regards, Romain.

  65. avatar chris boothe says:

    Hello, I would like to install a low battery led indicater on my roland micro cube.I do a lot of outdoor gigs and there is no way to know when the batteries are getting too low. I called tech support and the guy said, “Gee, we don’t a lot of calls like this”. So, no help. Anyway, what is the cutoff voltage for this model? I found some circuts but I need to know which zener diodes to get ie, voltage ,680ohms 3.6volts ???? to trigger the led. Thanks for any help.Chris

  66. avatar step says:

    Hello, I just bought a micro cube from a pawn shop and the tuning fork doesn’t produce any sound, any input on what could cause this ?
    I opened the micro cube already, opened the push pull button and contacted the poles from the switch with a screwdriver , no results as well.

    Any input/advice/opinion would be appreciated.

    Thanks

  67. avatar smurfitt says:

    COSM and EFX not working so only get clean channel. Anyone know what is wrong?

  68. avatar John Myles says:

    My son plugged a wrong ac/dc plug into my Roland cube street. Now it will not power up on batteries or with correct plug. Is ther a fuse? Is it likely fried? Love this amp and would like to save it.

  69. avatar lobo says:

    Hi, I’m going to repair a micro cube that fell down and I need to change 3 potentiometers, TONE, EFX and DELAY/REVERB. I’m going crazy trying to find them. Can somebody help me with the reference of these parts? where can I find them? or any other solution?
    Thanks

  70. avatar ed fraga says:

    hi can youplease tell me the value of the red capacitor next to the input jack? mine is burnt and i need to replace it.

  71. avatar Wade Gardner says:

    Hi, I have a Roland Cube 100 Watt, at rehearsal I was running a compressor, boost and od pedal into the input with the outputs of the pedals turned up but the amp less than half way up. Then the amp stopped playing no sound at all, even though its power indicator was still on. I then plugged straight into the amp without any pedals, still no sound, after a few minutes it came on and worked fine. Did I overload the amp? Should I not use pedals with my cube? Was there a power surge and this is a built in protection? It makes me nervous depending on the amp at a gig, even though it sounds ok and has never again done this. Thanks, Wade

  72. avatar James says:

    I have a issue with the main switch not going to classic stack or acoustic it seems to be stuck on one sound does anybody know what the problem could be

  73. avatar Hantonius says:

    I also has the same problem with the COSM amp modeller. It won’t work, stuck in the clean sound. I’ve check the rotary switch but it seems okay. Any ideas, where the problem is? Is it the rotaty switch, the COSM circuit board or the main mother board? Thanks

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