I have a casio wk-200 piano. I bought headphones

If the volume wheel on your Casio WK-200 keyboard is spinning all the way around and not stopping at the "min" or "max" positions, it is likely that the potentiometer that controls the volume has become faulty or damaged. A potentiometer, or pot for short, is a type of variable resistor that is commonly used to control the volume on electronic devices.
Here are a few troubleshooting steps you can try:

1. Power off your keyboard and unplug it from the power source.
2. Remove any batteries from the battery compartment.
3. Locate the volume potentiometer inside the keyboard. It should be near the volume wheel and will have three pins or legs.
4. Check the potentiometer for any visible signs of damage, such as cracks or broken pins.
5. Gently wiggle the volume wheel while observing the potentiometer. If it appears to be loose or wobbly, it may need to be replaced.
6. If you have experience with electronics and soldering, you may be able to replace the potentiometer yourself. Otherwise, it is recommended that you take your keyboard to a qualified service technician for repair.

If the issue persists after attempting these troubleshooting steps, it is likely that the potentiometer needs to be replaced. In any case, it is best to seek the assistance of a professional technician to avoid causing further damage to your keyboard.

Question moved from Cars and Trucks to a Casio Keyboard one.
Easy enough if you can find the part.

https://www.google.com/search?q=casio+wk-1250+parts+diagram

casio WK1250 Parts and Accessories - PacParts

https://www.pacparts.com > model > model_id=WK1250
Mfg / Model No, Description, PDF, Year. casio WK1250, Musical Instrument: Electronic Keyboard, 1998. The following parts are available for the model listed ...

Casio WK-1250 Repair Parts and Accessories - Syntaur

https://syntaur.com > keyboard > keyboard=2080
Casio WK-1250. Released in 1998. The WK-1250 is a 73-note consumer keyboard with built-in speakers. Synth. All photos are copyrighted by Syntaur, ...

Casio Keyboard Junkyard: Welcome

https://casiokeyboardjunkyard.com Used accessories, parts and stuff for Casio Keyboards ... CASIO WK-1200, WK-1250, WK-1300, WK-1350 models are basically the same and use the same parts.

Casio Repair Parts - Keyboard Kountry

https://www.keyboardkountry.com > keyboard-parts
Casio Repair Parts ; Yamaha Brand Key Lube (Small). $3.80 ; Casio CTK-560L Ma1M Light Boards. $9.95 ; Replacement Keys for Casio CTK-491 and Others. $10.95.
Missing: 1250 ‎' Must include: 1250 ..

Well friend,
According to page 24 of the manual here http://support.casio.com/pdf/008/ap_45_e.pdf
It says
Demo tunes
While holding down the MUSIC LIBRARY button,
press the PLAY/STOP button
.....and try to play a specific demo tune ........
After playback starts, press the tone button that
corresponds to the tune you want to play.from the list.

ALSO in the Troubleshooting section page 35 For DEMO tunes UNPLUG HEADPHONES

If it doesn't work, then you need to get a Technician to look at it.

You bought the wrong model - e.g. Yamaha models work reverse.
Return for Exchange
Or try opening up and re-solder the cable to the micro switch if possible

Jeremy hi
you must open the piano and change the headphone jack

Get a
Universal 1/8" to 1/4" Headphone Adapter

The output of the casio may only be mono, you can buy splitters to create a 2x channel output. Is there any other outputs from the casio other than headphones, usually there are red/white RCA outputs (Phono's) which would be better for connecting to your soundcard.

Hope I was of use to you, good luck.

Here is one:

http://www.amazon.com/Casio-AD-12MLA-Adapter-Power-Supply/dp/B00029HDT0

and another, less expensive on Ebay:

http://cgi.ebay.com/Genuine-AD-12MLA-12V-2-5A-2500mA-AC-PowerSupply-ADAPTER-/390280683299?pt=LH_DefaultDomain_0&hash=item5ade8a9f23

yes its in the keyboard jack.

Most of these have VELOCITY sensing and that involves two contacts per note. If the velocity sense on those notes is somehow not working, broken wire or trace on the board or short that MIGHT cause your problem.