"wk-3700" is wrong. Where can I buy parts to it?

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 ..

It could be a fuse if you are lucky. It could also be a protection diode. You need to open it up and see. If you are unsure of how to do this, you should take it to a repair shop.

Sounds like either the contacts are dirty or worn out. Solution clean / replace.

Pat, the USB output on the Casio WK-210 is only capable of sending and receiving MIDI information. It's not sending any digital or analog audio. Audacity is primarily for sound file editing.

In order to use the keyboard to record onto your computer you can connect an audio cable from the 1/8" stereo mini-jack to an input on your computer. Then you can record into Audacity.

Or you can acquire MIDI recording software (ie. Logic, Cubase) and then using the USB output on the keyboard, you can control and record multiple MIDI instruments in those programs.

Go to www.casio.com support. If that dosent help go to contact us and call directly

Check the power supply voltage or try another adapter.

The keyboard has a mic jack that is the same size as the headphones. You probably put the headphone plug into the wrong jack is all.

The specs for the adapter are:

9 volts DC

850 ma MINIMUM

Center pin of connector NEGATIVE

If you find an adapter meeting these specs it should work, however I would recommend getting a regular Casio unit. They are under $20 USD and the part number is AD5.

One portion of the key scanning matrix has gone bad. First thing is to clean the contacts with 99% isoprophyl alcohol. These USUALLY consist of traces on a circuit board that conductive rubber "pills" under silicone rubber domes are pressed down. Each note usually has two contacts, one closes before the other. This creates "velocity" measurement for the key. IF ONE of the contacts for a key doesn't work, the velocity can detect that the note has actuated, but no release occurs.

This would be on the "STROBE" line for either the first or second contact for THE OCTAVE you have problem with. There are disconnect diodes that prevent sneak paths.

You could have one bad diode, a crack in the circuit board, or a bad connection to the keyswitch board.

No.

I have a Wk-8000 & a CDP-200R, the later is the same as wk-500 but with 88 weighted hammer keys.

Since wk-500 can play SMF (Midi 0 & 1) format directly from a SD card and there is enough polyphony to play anything, I don't find any real reason to convert SMF to any "Casio Format". Just get a 2GB SD card and put your SMF files in the MUSDAT folder for the SD CARD using your PC/MAC.