Roland Ac-90 Acoustic Chorus Guitar Amp Ac90 Free Ship - Answered Questions & Fixed issues

I would expect there is bad soldering or a circuit board crack. Inspect the soldering aound the leads, especially pots and heavy components. Finding all the retaining screws can be frustrating. Expect the screws for the handle to also attach to the amp chasis. They are often hiodden under plastic caps.

There may have been a power surge that took out the fuse. At least that's the first step.

I don't have the exact schematic... however sometimes they have RF bypass capacitors to ground on the balanced input lines and one side gets shorted. The schematic I do have is for an AC100. It shows a rather unconventional input circuit. You can download it here and it MIGHT be close to your unit:

http://elektrotanya.com/roland_ac-100ut.pdf/download.html

I note that this unit does NOT have Phantom power so you CANNOT use a condenser type mic with it unless you use a preamp with Phantom power... Maybe that is the problem?

This unit has a TDA8920 dual switching class "D" switching amp chip that is thermally protected. If you heat it up it will shut down to protect against overheating. Each side of this is ONLY a 50 watt amp chip HOWEVER they run it at a lower than rated voltage that limits it to about 30 watts per side. Your dial setting number have NOTHING to do with the power limits of the unit. When you use the looper, there are more frequency components added, and all these consume part of the available power. Also make sure the mics and the guitars cannot "hear" the speakers in this otherwise high frequency feedback may occur above what you can hear and use some of the capabilty... hint... reduce the treble boost... The only way to measure the power output is to put a scope or test equipment on the output and compute the power. I suspect you are driving the unit too hard. The unit should give adequate output for a 15 foot square room to a level that *********** could just barely tolerate. Yes, the power amp chip is thermally protected and if you drive it to hard it backs the power down till it cools off.

That will be step 1 to what will probolly become quiet a bit of problems. I'm not huge on this unit but generally speaking if you opened the chassis your going to see a few burnt components (rectifier,diodes,transistors). But lucky 220 hits so hard it's usually just a replace the stuff you see burnt (get schematic if possible) it's a pretty straight forward repair.

I wonder why the ribbon cables have been replaced as they do not fail. Check the keys actuate the contacts properly.

I can't! In my opinion, no. Start drift boss customize your car by choosing different colors and patterns.

most likely we dont have crystal balls --need to have diagnosed for problem

Yes, you can use the second pedal on a Roland BK-5 keyboard to transpose the key of the music that you are playing up or down by a semitone at a time. To do this, you will need to press and hold the second pedal while playing the keyboard. You can also use the transpose function in the settings menu of the BK-5 to adjust the key of the music that you are playing by a specific number of semitones.

I am also using IOS and Android. So how can I improve some features? The black screen helps you relax when using the computer too much.

Question edited for a bit more clarity. Video that might help https://www.google.com/search?q=Roland+octapad+spd30+dead Owners Manuals only. https://www.google.com/search?q=roland+octapad+spd30+service+manual ..

It's a Chinese made Roland and no service information is available as when a fault is found the main board is replaced, eliminating the need for service information. I would check that it is a stereo out jack and not mono. If it is a stereo out, check that both input phonos work. If they do, replace the faulty socket or damaged pcboard.

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This depends entirely on what you personally define as 'Good'. The only real answer to this is try it, listen to it and decide for yourself.

https://www.google.com/search?q=Roland+rd100+sustain+pedal+replacement ..

Read this please https://www.justanswer.com/electronics/9xlyw-roland-digital-piano-kr-4500-piano-turns.html and these https://www.google.com/search?q=Roland+kr+4500+no+sound But you will probably need a service centre for replacing components.

Being mainly digital, I would reset the processor and try again.