The Repair Bench: Roland Micro Cube
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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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.
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
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
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
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.
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?
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
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?
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
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
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
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
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
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
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.
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
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.
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?
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
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.
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.
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.
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
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 .
Paul, that’s great news but also a little unsettling. Just curious – what power supply did you use at the dealer’s location? Was it yours or the dealer’s?
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.
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?
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.
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?
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
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)
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
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.
I’m having the same problem now but I can’t find where the fuse maybe yet.
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.
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
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
Old thread.. but I still have the micro cube and with the same problem. I guess the COSM modeling is stuck in Acoustic no matter the knob position.
I opened it up (thank you very much Jeff for the instructions!) and examined the switch to see if there was any obvious problem. I don’t know the technology involved – this switch is not a potentiometer so it could just send signals to the unit’s processor just as a keyboard does. Only thing I know is that the knob communicates with the mainboard via 3 wires.
I tried bridging the 3 wires with a screwdriver and found out that bridging quickly pins 2 and 3 makes the unit switch back and forth between acoustic (or no effect, i guess) and one highly distorted model (I am not sure but sounds like British Combo).
I am trying to find schematics, no luck, and I wonder what else could I try. I dream it’s some soldering problem. And I fear of course to be an internal (processor or mainboard) problem which would be out of my reach.
Further testing… I guess the COSM selector knob IS actually a pot (in a small board labeled “main board 4/4) with some other elements (resistors, diodes?).
From the 3 terminals, I tested with a multimeter and I found a 10k ohms from center terminal to either side. (give and take) so I guess it’s a 20K ohms pot which output stuck in the middle. That would explain why it seems to be stuck in the BRIT COMBO which is the center position.
Before doing any unsoldering, I tested some of the 10 pins attached from the knob to the board and saw their resistances are different in relation to ground so maybe these pins are outputs from different points on the pot “coil” (sorry I’m guessing terms here).
I have a 50K pot here. I managed to hold this pot as a bridge to pins 3 and 5 on one of the rows. Now I play some chords (with my feet at this point) and turn my 50K pot, and I can listen the sound changing to at least 5 of the COSM models. Of course the sounds are all stacked together in one half of the 50k pot range, as would be expected.
So At least I can conclude that it’s a problem with the switch itself.
I wish I had more expertise in electronics and find a better solution. Only thing I can think of is replacing the whole board with the knobs to a 20k pot. I will lose the 7 position snap, but it maybe works. I would be able to do that myself. Any other suggestions?
I also have a microcube that is stuck in JC clean the cosm amplifier switch has no affect whatsoever.
Same problem here – while chorus and delay switches work, the COSM and gain switches have little or no effect. Did anyone find a solution please?
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.
Same problem-Micro Cube will only work when plugged in. Can anyone help?
Same problem in 2016…wont work on battery mode…
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?
did you ever fix your broken power button? Mine just broke a few days ago
Oh, and thats on a micro cube.
micro cube 2watt that is
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.
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?)
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
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!
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
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?
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?
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
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.
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?
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
Also having the same problem, sat for a few months, and no luck with the COSM switch. Please help!
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?
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!
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!
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?
Nobody?
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!
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…
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!
Nice post. I was checking constantly this blog and I’m inspired!
Extremely helpful information specifically the last section 🙂
I care for such information a lot. I was looking for this certain information for a very long
time. Thank you and good luck.
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.
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..
@Blues: Thanks for the posting.
I had to wait a few weeks for the switch to arrive, but my Micro Cube is finally working again. Either the part number has changed or it is wrong in the posting above. The switch I received has the number 5100032980 and is working fine.
Taking my Micro Cube apart was a real pain. There are videos on YouTube which explain how to do it. The foam in my Micro Cube stuck to the wood which required some force to remove the back of the amp.
A couple questions. Is the part only available as the whole assembly with 12 solder points, or can just the top half with the knob and moving part be replaced without removing the other 10 solder points? What method works best for unsoldering–I’ve tried the bulb-style desoldering tool from Radio Shack with no luck, as well as a soldering braid, but that’s not working well, either. Part of the problem may be I don’t have a very fine soldering tip handy, so it’s tough to focus on such small points.
Probably a little bit too late, but here are my answers: If I remember correctly, the part is only available as the whole assembly. Unsoldering the old switch took me forever. I don’t remember how I did it. I think it was a combination of patience and brute force.
Does someone knows how to reset Roland Cube 30x amplifier?
Thans a lot
Luis
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.
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
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
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
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?
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
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?
Very rapidly this web site will be famous amid all blogging people, due to it’s nice content
Does anyone have a schematic with the parts list for the Micro Cube N225?
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.
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.
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.
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
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
COSM and EFX not working so only get clean channel. Anyone know what is wrong?
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.
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
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.
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
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
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
I have the same problem.
Can you fixxed? How?
Tks
Hi my friend has a roland street cube he can play his guitar ok through it but when he plugs into the aux in to play music through his phone it kills the sound
Any help would be appreciate it.
Gary
Hello
I am looking for a particular part in Roland micro cube amp.
Everything works except the switch for types of amps.
The metal ball with a holder plate was loose, i got it in and secured it.
But, seems like, it didn’t help because, i think, that the black plastic part that goes up to the knob is not making the contact: basically, if i vigorously rotate rotate the knob i can get either clean or some overdrive sound (out of seven settings) and it gets stuck on that unless i rotate many times.
So, i need that one.
Please see attached photos.
Thank you in advance.
D
I haven’t seen this problem posted here (or anywhere else) but I’m sure someone else has had this issue! I’ve got a Roland cube 80GX that I bought new. Occasionally I seem to lose signal in a very peculiar way, it’s like the noise floor is highly elevated and the signal (guitar) is weak. None of the potentiometers or switches change it when it occurs. I’ve tried changing guitars, cables (and bypassing any pedals if present in the signal chain), and tried switching from JC Clean to lead to solo without ANY effect whatsoever. It’s a very intermittent problem. Yesterday I noticed another problem with the i-cube link popping and making horrible noises while jamming along with my iPhone. This amp is in new condition and this problem has been driving me crazy since it was just out of warranty. Any help from Jeff or another reader will be highly appreciated! Cheers!🎸
My Roland cubes battery plate has broken and I need a new one, because I want to sell it. How can I find a replacement? Thanks!
Hi,
I’v purchased roland M cube 4years back and it was working perfectly ,but from few days i noticed that there is sound issue , like of missing of the note , and missing the right effect , i changed the guitar wire , but still black panel , brit combo , r-fier, classic stack aint sound , like they werw before
I am not able to explain properly , but yes its a big problem
Can’t get the bigger (red) jack off the speak. The little black one came right off but this sucker seems locked on somehow.
Ah, got it out by unscrewing the speaker itself and pulling the connections out the front, where I could get a much better grip. It was soldered in the back but I got it free.
Hi
My Roland Mobile Cube is a great little amp and it works well on batteries but when I plug it in to a 9v dc power lead there is a buzzing sound heard through the speakers. I dont think that it did this when it was new. Its about 18 months old.
Can you help
If anybody has one of the replacement jacks, could you provide some info regarding the jack itself? There’s four connections, from the video, but only two seem to be needed. I’d rather just get a regular jack, and wire it in. That way, there’s no plastic body, and the jack should be more durable, and get rid of the possibility of damaging the control next to it, since the jack would not be mechanically coupled to the circuit board. Also, it would only cost 2 bucks. Less than the cost of the replacement nut, which is 5 bucks. Also, if anybody gets a schematic, I should be able to help fix all the other problems I see here, and suggest cheaper, more durable replacements. I’ve got a degree in electronics and used to teach electronics.
I wondered if you could help me locate a transformer for my Roland Bass 100 watt amp, mine has a short ciruit on the primary coil .
I wrote to Roland USA and Roland UK to no avail . It is 240v one for the UK.
I even considered 110 volt but that wasn’t available either .Can I use an alternative transformer?
Hi guys, so it seems that a lot of us are having the same COSM switch problem (it won’t switch modes). Some friends up there have managed to buyt spare parts from their region’s Roland service centre. Unfortunately my region (APAC) doesn’t sell spare parts to customers, preferring us to send it in for repair, and I have a problem with that, I want to fix my own amp.
I did some digging and I think I found the correct (or similar) model of rotary switch that we need, it is a 1P8T , PCB-mount rotary switch. I found a China supplier for them but they only take minimum orders of 500pcs.
More digging resulted in me discovering that there is an ALPS (great brand) R17 rotary switch that appears to be the same type of rotary switch. here is an ebay link that I have ordered one piece from, it costs USD899 before shipping.
They come in different stem lengths but I think the longer ones can be cut or filed down to size.
https://www.ebay.com/itm/ALPS-R17-1-Pole-8-Position-1P8T-Rotary-Switch-20mm-D-Shaft-Rt-Angle-PC-Mount/252641490131?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D52475%26meid%3D5b1165e29f90443bae56b0abed75b9d2%26pid%3D100623%26rk%3D3%26rkt%3D6%26mehot%3Dlo%26sd%3D253044978852%26itm%3D252641490131&_trksid=p2047675.c100623.m-1
DISCLAIMER: I have yet to receive my switch as it is still shipping and expected to arrived in Jul/Aug, if it works I will report back here.
If you want to try it out before that, be my guest but know that there is a chance that this might not work out!
I have a Micro Cube that works great except for one odd problem. When I run a cord from my laptop to the Aux input of the cube, Eto play a jam track, it works fine for about 4~5 minutes. Then the Aux signal disappears. If I unplug the Aux cord and plug it in again, the signal comes back for about half a minute.
While all this is going on, the normal input works just fine. If I use a small mixing board I can feed both the jam track signal and guitar signal into the Cube’s 1/4″ input jack and it works fine, but the jam track now picks up all the “effects” I normally use for the guitar. Not the best setup.
Has anyone ran into this before? any suggestions?
Thanks
Hi,
I have a cube 20 gx with the same problem…can you fixxed? How?
TKS.
Hi,
I have a cube 20 gx and the effects don’t change only the clean channel. I can’t use the tuner top.
TKS.
It’s possible reset the system?
Hi,
I have a roland cube 30 witch I rarely use. The amplifier is in a perfect condition. Now in my new house I started playing guitar again. I noticed that the delay/reverb doesnt work. Any idea?
thank you in advance
ello
in my Micro cube of the first series, I can not switch the different amplifier models. It’s just more clean Sound
thank you
R.
I have a cube and it’s brand new. I’ve noticed the effects are way too low a level. You can bearly hear them. This includes the delay and reverb as well as the chorus and flange. Any ideas?
I have a brand new Roland Mobile Cube. I only use the mic – and it intermitently cuts out during use. When I power off then switch back on it works again – but will cut out again minutes later. I don’t think I’m running the mic to loud. Any ideas?
Hello I’m hoping you can help.
I bought a micro cube at garage sale worked fine. I bring it home and turn it on, and a ticking or tapping noise is coming out of the speaker. What would be causing this?
I have a Micro Cube I have not used for ages. Plugged it in. Nothing. Red light on. slight click to the speaker. After a few moments a regular clicking noise starts. Circuit board gets warm. I checked the power supply. Unfortunately left plugged in. Producing 14V! Fitted batteries. Acts the same. Controls make no difference Tried mani and aux inputs.
Good afternoon. I will raise the topic. Need a circuit from (Roland MICRO CUBE T225. The chip of the controller PWM burned out. Do not determine its value. Thank you for your help
Covid quarantine life support question haha. Ive had an issue where i cant get the EFX to turn off. Somehow it got stuck on the smallest level of chorus possible, but we cant have that. Im going insane not being able to play my whip on a working amp!
Great product though!
Hello friends
My Roland Micro Cube, first model, suddenly, stopped working the selection of amps.
Everything works – modulation, ambience, tone., volume, gain, tuning fork, all the in and out connections – except by the amp selection.
Sounds like it stopped in a clean mode.
I opened it, and it looks like new! No dirt, no signs of bad solder, nothing wrong apparently.
I sprayed contact cleaner in the rotary switch, but it didn’t work.
Any ideas?
Thanks
I bought a the cube, a 10w model in Jan of 2018. It has been in the house all that time. I have played it at the most 6 months, I am disabled and my health just not allow me much fun time to play.
I turned it on today and there is no power. I tried different outlets and still no power. I put batteries in and it is still dead.
Is it worth shipping it to you and so on to get it fixed? I paid $140 for it a Sweetwater sound. They have no idea or help for me. There warranty is up.
Please advise me what to do. Ps. I have never played it loud and I have used nothing but a classical Yamaha silent guitar with it.
Thank you for your advice
Jake