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Roland cube 60 broken lead channel.

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  • #16
    Hello thanks for answering . the amp is not stuck on the clean channel. When I press the bottom for changing channel it changes from the green light to the the red one that is on the lead channel. Then I hear the guitar signal is getting some gain but nothing more because I change the type switch to all modelings presets but remains the same ( guitar sound with some gain) . Because I read one of the comments above saying that he found the solution when he said ' I super glued the wiper contact back into place because the plastic tabs had broken off" I would like to know the steps he followed to take apart the type switch . I have take off the chassis panel out but I don't know which screws unscrew to get to that part. With the panel out I sprayed some detox it near to the type witch( I guess cause I can not see exactly where I was spraying just approximately ) and later When I turned on the amp and moved the type switch it was changing the sound to a high gain and low gain mode. But nothing more changed, that keeps me thinking I have the same problem as the one on this thread. If you can indicate me which are the screws to move and in which order ( among other precautions I don't know ) I would really appreciate your help. Again thanks for answering.

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    • #17
      There is a metal bar that runs top to bottom across the back of the chassis. It will have one or two screws at each connection point. One of the screws there has a green ground wire attached as well. Remove that metal bar. Locate the two molex type connectors that run from the upper board to the lower circuit board. Disconnect those from the lower board. Loosen and remove nuts for the pots and jacks. Once that is accomplished then you can remove the upper preamp circuit board. It is a tight fit so be careful pulling the board out of the chassis.

      The switch for the amp models is on a small little circuit board and it flops around connected to the larger board by a ribbon cable. That switch will have about 8 legs soldered to that small board. It is very tedious to de-solder that switch from the board.

      I need to revisit that schematic but if that switch is functioning by switching through each amp model then I am a bit reluctant to say that switch is the problem. From memory there is a DC voltage divider that just switches between each amp model. I will look at the schematic when I get on my computer later to look at the signal path.

      Edit: looking at the schematic I get it better. That little button switches over to channel two, I forgot about that. It could be the amp modeler switch is not making good contact. It's a pain to get the switch off and chip quick may help a lot. Google chip quick. Once you get the switch unsoldered the are little tabs you bend up to take it apart.
      Last edited by DrGonz78; 10-28-2018, 08:42 AM.
      When the going gets weird... The weird turn pro!

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      • #18
        Hello DrGonz78. You really have helped me. Well my amp technician skills( which are almost none)have taken me to a certain point where I am seriously questioning me if I am able to do the procedure you are describing . But I have to take the risk . I will post in this thread the result of my endeavor. Wish me luck . Thanks so much for the time you have taken . I really appreciate it .

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        • #19
          Yeah it's a lot of legs on that switch. I think actually 10 legs and 2 more if you count the ones for mounting. Hopefully you have some solder skill and if you get it right you'll gain some even. Good luck
          When the going gets weird... The weird turn pro!

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          • #20
            If you can't repair the pot, worst case is you will have to order the encoder pot from a Roland dealer and replace it.
            Originally posted by Enzo
            I have a sign in my shop that says, "Never think up reasons not to check something."


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            • #21
              Hi again this is to Inform you the repair thing went wrong, I can not disassembled the circuit board, I unscrewed the metal bar , take out the nuts from the pots and jacks . But there was a kind of heat dissipator a black big metal block interfering the extraction . So I leave it but I sprayed some Deoxit on the channel changing button and on the type switch, again I obtained some amp modeling changing (stack and metal ) but after few minutes it returned to the faulty state ( guitar signal with some gain added. ) I never was able to detect which is the defective part. But aside of the aftermath I wish to thank you for your time dedicated to clarify some path to repair. I guess from now I can use the Roland cube 60 as a one channel amp adding pedals in front of it and still capable of using the delay/reverb, chorus/flanger/phase/tremolo from the Roland effects section cause they are still usable. Not all effects are gone just the amps modeling, I guess this unit has its days counted,

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              • #22
                Yeah that upper preamp board is a tight fit. As you slide it out it might even feel like you might break it or that it is gonna get wedged stuck. I had another Roland cube 60 that had a bad LM3886 chip. I took that thing apart at least 5-6 times while doing the repair since there was several faults to address as I went along. I basically had that amp sitting in the shop for months and in-between other repairs I would torture myself with that repair. When I finally fixed it I sold it cheap for just the money I had into the amp.

                So right now it feels like you could not repair the amp. Who knows you might come back to it at another time and with a fresh start. Even experienced techs run into this issue every once in while.
                When the going gets weird... The weird turn pro!

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                • #23
                  Also when you slide that board out of the chassis it doesn't come straight out the back. There is no way that thing is gonna clear the black heat sink. Instead you have to pull it out so it slides to the far left side of the chassis, left meaning looking from backside of chassis.
                  When the going gets weird... The weird turn pro!

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                  • #24
                    Good day to you all-
                    I registered on this forum to reply to this wonderful post, and will likely also enjoy membership here!
                    I wanted to add to this information for anyone in the future having this exact same problem; a Roland Cube 15, Cube 30, or Cube 60 in X, XL, (or whatever) trim with a broken / non-correctly-working LEAD channel. This issue likely will or has happened on any of the Roland amps which utilize a multi-position rotary switch to change between different amp models / tones / modes. Roland is not immune to the "less for less" malady of modern electronics, and this rotary switch surely is a perfect example of a supplier cutting costs to make a part two cents cheaper. Unfortunately, these parts are in our amplifiers which we expect years of service from. In the old days, these kinds of parts were pretty much the same from various manufacturers, and also were easy to source at your local electronics supply house. Nowadays, manufacturers will make a design and cancel that series within sometimes just a few years, leaving us high-and-dry to find a replacement, or getting a single replacement for what was originally a $2 part for the manufacturer of our device now costs almost as much as just pitching the device into the garbage and buying a new one.
                    Thankfully this switch is repairable. The only skills required are knowing how to solder, desolder, and turn a screwdriver.
                    For my issue, it was a Cube 30X with a dead "lead" mode. I could spin it from left to right, and other than feeling the individual detents in the switch, nothing would happen... still the same low-volume slightly distorted sound in every detent. I figured it was the switch, but before tearing into the amp, I discovered this thread. After reading this, I knew exactly what to expect. So I took a few pictures of the switch as was found. After affixing the fingers with a small dab of JB Weld epoxy, I don't imagine the switch will fail again.
                    I did not take pictures of the disassembly, as it was pretty straight forward; remove the screws along the bottom of the amp plate on back, and remove the two handle screws on top. Press down on the amp plate on top - the part where the pots, switches, and jacks are mounted, as there is some sticky foam that is squeezed between the wood cabinet and the metal plate. From there, just disconnect the speaker leads. Removal of the circuit board should also be pretty obvious; a couple of connectors, a few tie-wraps, a couple of screws, the nuts on the potentiometers and switch, and it all comes off.
                    Desolder the switch, and bend the four little tabs which hold the plastic body to the metal body so that the plastic body comes out. Be mindful of the detent ball and spring. Find the broken finger, glue it to the rotor/shaft, and reassemble. I found it easier to just remove the detent ball and spring, put the shaft in, bend the fingers back, and then reinstall the detent ball and spring. Re-solder, re-assemble, and jam!
                    Thanks, DrGonz78 for doing the initial leg-work on this!

                    As I found it... the fingers came detached:
                    Click image for larger version

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                    The shaft/rotor assembly, sans fingers:
                    Click image for larger version

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                    I thought I had a picture of the fingers glued to the rotor, but I don't. Sorry!
                    All-in-all, I'd rate this a 1-beer job to repair. The most time consuming part was waiting for the epoxy to dry. Well, that and my fat fingers with little, tiny parts.

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