Casio - 120 Turns itself off randomly

Lose up the power button

I would urge you to contact https://www.casio.com/products/electronic-musical-instruments and see if their service department can help you.

You may be running out of internal memory. Try deleting, songs & SMF etc that you may have recorded to INF AFTER moving them to an SD CARD first.
IDES4 can also be used to move user tones etc and do a factory init.

Casio CDP has Auto Power Off: 30 minutes after last key operation, Auto Power Off can be disabled.
Please read the manual.

If it turns itself off while playing, I would try to buy a new AC Adapter to test. DC cable of AC adapters are often broken internally after much "bending".

That is probably a momentary switch that is dirty and sticking. These onboard effects on guitar amps are usually nothing more than a computer sound card and I've found bad connections going to and from them as well. I do think that switch is dirty and sticking, though.

I would check your fingering... You MAY be late in hitting a particular note and the using auto chord... this can cause the problem. Another thing is if notes are hit with different velocity that can affect the sound. Sometimes certain voices have VELOCITY switching which actually changes the voice depending on the velocity you hit a note.

The adapter has a problem... likely a poor connection of input power that briefly contacts building up some voltage that is then stored in the capacitors in the adapter which then discharge quicklly when you turn on the Casio. The adapters with FIXED blades OFTEN have problems contacting the connections in wall receptacles and extension cords. You may need to bend the blades slightly or use a better receptacle like connector. IF your adapter has a three wire cord from it to the wall receptacle, those SOMETIMES don't seat well...

Sometimes companies use the same sequence for all their synths...

Here is one to try:
How do you reset casio keyboard lk-60?
This is how. 'Turn keyboard of for 5 seconds then turn it bak on and play"e-flat,g-flat,e-flat,b-flat,g-flat,e-flat,g-flat" then turn keyboard of and unplug and wait 5 minutes then plug back in in,...
Note: It is NOT clear if you need to hold the notes down as you play them or press and release.

Here is another for Casio:
From the FILE menu, select INITIALIZE to select the sub menu. Select the SYSTEM option to return the keyboard to its factory settings. Keep in mind that this operation will delete anything that is stored in the keyboard memory. When you see the InitSys? on the screen, select YES. I hope this helps......

I could not find anything specific to the 810.

If these don't work, then the way to reload is via the MIDI port which will accept Sysex commands and data. You can probably find a data dump online for this at the Casio site..
You will of course need to have a MIDI port on your PC.

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.

Try plugging in a set of head phones , if you get sound that way the input jack may be causeing the prob. try pulling it back an forth a few times, sometimes this will free up the head phone jack. I hope its that simple . May be some one will have another idea Good luck DFD please rate me TK U