CASIOTONE 403 ISSUES - Note sustain never ends even with sustain effect off.

[humanchiapet]

Example

 

Less than 6 months ago I purchased a Casiotone 403 off offerup for a pretty good deal. At the time everything was working great!  The chord memory was fine, the tone memory was fine, and the drum machine was fine. I was using it probably everyday for a total time of a 30-60 minutes a day. All of a sudden after not using it during my College finals, I come back and it seems the keyboard is broken. Whenever I play a note the sustain never ends, this is especially annoying because now I can not play chords without it sounding like a horror movie. My chord memory section also stopped working, but on occasion it will work after messing around with it for 10 minutes. 

Any troubleshooting advice? Did I do something that caused its breakage specifically that I should try to prevent for future references? Was it the change in extreme cold weather? Please let me know anything!

 

 

[CYBERYOGI =CO=Windler]

Check the sustain pedal jack connections. Many early Casio keyboards play infinite sustain (until polyphony runs out) so long the sustain pedal is held. Hence a shorted contact or capacitor there would cause infinite sustain. Technically the sustain pedal is part of the keyboard matrix (simulating a non-locking button press) but likely has an additional transistor or 4066 IC etc. for decoupling it from the rest of the matrix (to make it DC controlled). If the part shorts, you get infinite sustain.

 

In my Casiotone 401 with the "memory" switch the current chord is held after key release (with or without rhythm). The chord voice uses a different chip TMS3615, which analogue sustain length control voltage is at pin 3 (datasheet falsely claims 4). AFAIK in Casiotone 403 the main voice sound CPU is a D990G (a bugfixed D776G?, like in MT-60) that activates its "hold" (sustain) pedal through a diode from pin 17 to 25. The sustain switch is 17->26.

Edited February 28 by CYBERYOGI =CO=Windler