The Roland Micro Cube is a 2-watt, portable guitar amp. It weighs just over 3.18 Kilogram and measures approximately 10 inches high by 9 inches wide. It can be either battery or DC powered, making it an ideal companion for guitar practice on the move. Despite its small size, the Micro Cube does have a range of on-board effects, including modulation, delay and reverb. This is unusual for small, battery-operated amplifiers. If your amplifier doesn't sound right or is otherwise not performing optimally, troubleshoot the most obvious causes first.
Turn the master volume down. Turn on the Micro Cube, gradually increase the volume and play as normal. If the power light comes on, but there is no sound, the problem is not located in the power section and is most likely in the amplifier or circuitry or speaker. If there is sound but the tone is unusually "crunchy" or otherwise degraded, this could be a sign that the batteries have run out. Plug in the DC adaptor to switch to mains power. If this corrects the problem, the cause was flat batteries. If the tone is fine, but there is a "flapping" sound, you've likely got a torn or loose speaker.
Fit six brand-new alkaline, AA batteries. The Micro Cube can run for approximately 20 hours on battery power, so if you haven't recently replaced the batteries do so now. Use only alkaline batteries. If you have used non-alkaline batteries, this may cause poor performance.
Plug in a brand new guitar cable and turn on the amplifier. Don't play anything, just listen for any residual hum or crackling. The crackle emitted by a faulty or worn-out guitar cable can sound very similar to a faulty amplifier. Prevent misdiagnosis by using a brand new cable. If the amp crackled previously but doesn't when you use a new cable, the problem was not related to the amp. If the crackling persists, it is likely linked to dirty potentiometers.
Turn each dial on the front panel. If you hear an intermittent crackle or "fuzziness" when you touch each dial, it is likely that the potentiometers attached to the dials are dirty. The potentiometers are the resistors attached to the inside of the dial, on the inside of the front panel. You can get to them by removing the rear panel.
Unscrew the rear panel with a Phillips screwdriver to expose the interior of the chassis. Spray the potentiometers with a plastic-safe contact cleaner. Examine the circuit board and look out for any soot or brown discolouration, which are signs of a blown fuse or transistor. If you spot any, take the Micro Cube to a specialist for repair. You can invalidate the warranty by attempting internal repairs. Reattach the back panel.
Remove the front grille. Inspect the speaker for rips. If you spot any, take the amp to a specialist for repair. If there are no rips, gently push it. If the speaker is loose, tighten the screws holding it against the internal strut.
Shine a flashlight onto the speaker to identify fine rips. Radio Shack TV-Tuner/Control Cleaner and Lubricant works well on dirty potentiometers.