Hello, my name is Rusty. That particular model has a bad sub-power button, it's a common issue. Hold the button down, does that make a difference? How about if you wiggle your finger when you are holding the button down? Does it make any difference at all?
Hmm, sometimes it can be the cover that causes this, open the cover, then close it.
Has this been happening on and off for a while, or is it all of a sudden that it doesn't work?
With the cover on and closed, does that make a difference? Sometimes the sensor doesn't switch and it will not allow the button to function.
I'm sorry, but your dealer will need to come out for repair. That button is a known problem, and it's not a simple fix. Do you have a local Roland dealer, or do you need me to locate one for you? What is your nearest city?
Yes, click here. I'm working on finding the right part number for you, it is likely the sensor that has gone out, however sometimes it's the PCB below the button that goes out. Do either of the sensors on that page look like the cover sensor?
I have been searching for a free service manual, but only found this, click here. This will have the parts list, diagnostic checks, etc..., as well as disassembly instructions.
There is a diagnostic tool that I want you to use, this will send information to the repair techs. This should pinpoint the problem. Click here, and all the way at the bottom you'll see utilities. Run the utility, and it will check your printer. Tell me if you see anything abnormal.