I turned my Casio px575r on, after working fine for a couple of years, and get random synth sounds and volume blasts instead of the chosen sound.

Hi, Tracey.
There are three publications that may be helpful for you on the Casio support site:
http://support.casio.com/manualfile.php?rgn=5&cid=008009009
One is a User Manual. It includes a trouble shooting guide. Another is an appendix with a lot of "stops," or registration settings (voices). Also, there is a MIDI implementation guide. If you are needful of factory repairs, I think you will have to be in touch with Casio directly:
https://inquiry.casio.co.jp/support/contact/form_I_en_f1.html
Good luck to you. Truly.

the contact rubbers might be broken or the rubber itself is wornout because of usage or there is dirt in it.. its lose its touch response, the best easient way is to replace the contact rubber.

My Casio PG380 Synth Guitar...It lights up but no sound on the Synth..Any ideas..

ASSUMING you have a MIDI interface connection, (not audio) then you need to set the PC to use a general MIDI sound and turn on the synth in the PC.

Go to control panel and open the sound icon. Select the device to use for MIDI playback in the appropriate section.

This ONLY applies if you have a floppy or hard drive in your unit...

SOME of these synths hang up during boot if the floppy or hard disk isn't recognized as working...

Also verify your power adapter is producing the right voltage and is the original.

If you have a headphone jack, try listening with the phones to see if there is sound. Many of the synths have a way to defeat the line outputs and/or onboard speakers. Sometimes the headphone jack disables the speakers...

Not knowing your configuration regarding external amp/speaker makes it difficult to give further help.

Sometimes there is a mute button and of course the volume control.

Do look at the volume control and see if it MIGHT have been damaged as it likely passes the audio directly. The results of the test with headphones though is important!

There is no way to make a low-end keyboard model a Mini Moog decently.

You probably need to get up into the $1000 to $2000 range to get decent modeling of the analog synths... Go to a music store that has used equipment and maybe they can find an older analog synth that can get close. Maybe try to find a DX7II or other unit but be aware it takes talent to tweak the sounds where you would want them.

If the level is very low, this is what is known as "digitizing noise".

The waveforms from synths being digital in nature, have sharp edges that are filtered. There is a fine line between filtering too much and too little.

There is ALSO the statistical noise that is present in electronic devices that you can notice when you turn the volume way up.

These are all NORMAL and the nature of the beasts.

This may be a hard one to analyze, however my educated guess is that a static discharge is putting the internal processor in a program loop it shouldn't be in.

It is my experience that you MAY not even feel a discharge even.

Suggest you make sure to not wear static producing clothing as a test. Sliding across a piano bench might even create the discharge.

The unit SHOULD not be sensitive to this, but the designers don't always do things right.

ALSO make sure the unit is plugged into a grounded receptacle.

Use of external things like amps and headphones can WORSEN the problem of static. External amps MUST be fed from the same receptacle.

Okay, maybe this is rude, but TOTALLY ignore Musicaldude's solution, if you haven't already found out the ugly way. Boosting the signal that goes into the KP will just make the input LED light up red and you'll hear digital clipping [gross] and eventually hit a ceiling of all-crappy-staticy-noise and no real guitar left. Having it in the FX loop, and the Headphone-out workaround are smart moves already, except the Headphone out adds noticeable noise/hum vs the usual outs. But to help close the gap between your guitar's volume and the miniKP's internal synths (and program 63 and 65's feedback noizes, which build up even louder than the synths) unplug one of the RCA plugs from the KP's OUTput, pick one, left or right, whichever. You'll notice this gives you a guitar volume boost. BUT its still not enough...the synths and 63 and 65's feedback are still speaker-blowingly loud. Check the manual, it says you can adjust the wet/dry volume by holding down Tempo and Preset A together, then turning the knob and picking 1 thru 99. Make sure you're on the synth setting you want to use already. Do this thing. Play the synth with your finger, while you lower the number with that knob. Stay around 50 if you've got the one RCA plug dangling, around 20 if both are in. Whatever you think matches your usual playing volume. When its where you like it, hold the A or B button (wherever you want to save this) down and click Hold, this will save it onto that preset button. Now from now on, NEVER use 63, 65, or the synths if you're on whatever preset you DIDN'T just save. i.e. If you chose preset B, from now on you can just tap preset B and it remembers your volume adjustment from before, voila, normal-volume touchpad synth. But go back to preset A for every other effect, or you'll barely be able to hear the FX. KORG should've given us more preset buttons to save onto. Godspeed. I've never seen this site before, but I have this pedal, and experienced the same b.s. myself. Now I'm down to one preset button and quick knob-turning. Whee.