
From Our Mailbag: Repairing a Roland Cube 80XL
- Dec 21, 2011
- in Guitar Kit Builder - Repair Bench

Doc, we're happy to try to help diagnose the problem but we need some clarification. How do you know you’re having a problem with the COSM switch? In the owner’s manual 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. 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 you say is 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
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Did You fix it?
Have the same problem with XL40.
Apart from the concern raised by concern which vinnie excellently gave a solution— my problem is a total blackout— no power. If ever I get power it is stucked similar to what isaac explained. If there is power problem what could be it? thanks in advance.
When the switch is in metal or R-FIER it plays well but on every other mode I try makes a noise.
Can you help me?
Late reply but thought I’d message anyway. Came across this thread as I had almost the exact same issue as Lucas, although on a 40XL. Can confirm that Vinnie’s response below worked to correct my issue – the wiring harness I had to pull was the central 4-pin on the motherboard. On a final note – make sure you unscrew the 4 screws on bottom of the backside of the amp, the 4 screws at the top of the amp PLUS the 2 screws that secure the handle. The brains will come out easily after that :)
When I turned my amp on all lights go on at the same time, but nothing works, no sound. Any advise on this issue will help me a lot, thank you in advance.
I was able to fix this issues by pulling out the “main brain of the amp†and unplugging circuit board and plugging back in with the power on – i took out the 4 black screws on each side of the amp and the whole control panel pulled out of the amp – with the power on i disconnected the white wiring harness closest to the back of the amp on the right side and plugged back in and everything is working again .