My Roland Cube 20x Amp doesn't switch on after a sudden voltage increase! I turned the power supply off in a jiffy though!

1. Check the power cable and ensure it is securely connected to both the amp and the power outlet. 2. Check the fuse and replace it if needed. 3. Check the power switch and ensure it is in the correct position. 4. Check the battery (if applicable) and replace it if needed. 5. If the amp is still not turning on, contact Roland customer service for further assistance.

Your Roland microcube AC is waste up

Unfortunatly the impact from a fall can lead to numerous problems ranging from a broken fuse to a disloged power supply to a cracked board. I'd suggest taking it into your nearest Roland authourized service center to get it checked out. If you're not trained in electronics you can do more harm than good poking around inside the amp. https://www.roland.com/us/support/service_repair/service_centers

Most likely the acid ate the internal power supply, but if you can dis-assemble it and clean any trace of gunk with a toothbrush and electronic cleaner, including the fuse and it's contacts, maybe you'll get lucky.

Rubber cement is an excellent for minor speaker cone damage but if you feel that a replacement is required, try MCM Electronics online. They carry lots-o-speaker replacements. Be sure to match wattage and impedance (ohms) of the speaker though as these are important spec's.

What part of it got wet will determine the course of action.

If the whole unit were submerged, the unit may prove more time consuming to try to fix than to locate a used one. However, I have salvaged imersed laptops before. the procedure is not much different- make sure the unit is as dry as you can possibly make by blowing a fan on it for an extended period of time.- Days.

Once dried, use some contact cleaner on the jack contacts and interupts, any manual control and any switch.

You can then apply power. If nothing lights up, check and replace fuses as needed. Also check the power supply board for failed caps or rectifiers.

Once the power supply is known to be functional, systematically check the LCD display and the aspects of the amp that it controls. This board will be the most vulnerable and most likely to be the source of most issues you will encountr.

If the display survived intact, and amp does nto work, apply a signal to the inputs and trace the signal through the amp with a set of headphones set up with test prods. The problem will be where the signal stops.

have a look here:
http://www.ehow.com/how_8698510_fix-roland-cube.html

although it doesn't mention the fuse you will probably find it. Sometimes there is a fuse access on the outer case.

The winding is center tapped. It generates +/-24.5 volts DC. Based on it being a capacitor input filter, we need a peak voltage about 1 volt higher to account for the droop of the capacitor and the .7 volt drop of one silicon diode...

Since we need 25.5 volts peak then we need that divided by 1.414 RMS out of ONE side of the center=tapped secondary... So our secondary voltage is 18 volts either side of center.

You will need a 36 volt center-tapped secondary. Here is one that would work:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=162J36-ND

This has two 18 volt windings that you would connect in series and a dual primary you can set for either 120 or 240 input. About $19 US.

you can use the record outputs to run the signal into a stereo receiver without problems, though it would likely sound better with a shure sm57 microphone hooked up to a mixing board or other instrument amp.

the record output should be PERFECTLY balanced to hook up to a consumer-level stereo reciever with NO distortion; however, this record output might be too loud for another instrument amplifier or a mixing board; hence, the microphone in the latter situation.

short answer- "yes, but..."