Fx-20 troubleshooting

[Guest]

Hello, I have a Yamaha Fx-20 organ which freezes when you press more than 3 keys at the same time, someone knows what could be the problem or has seen some troubleshooting manual thanks, regards

[geoelectro]

The FX-20 uses a serial data chain to read the keys and tabs. There are custom IC’s incorporated to accomplish this. Replacements may be hard to come by. A service manual would be needed to determine which part may be bad. These parallel to serial IC’s were known to fail.

Is it any three keys or only on the same or certain manual? Any pattern you can detect?

Geo

[tucsondave]

As Geo says more information is needed including what you mean by "freezes."

If it is the keys that continue to sound, there was a service note from Yamaha describing that problem being related to the system controller interface IC-1. That part number was IT211400 or YM2114. They became obsolete in 1998. The last price at that time was $150.
td

[Guest]

Please excuse me, I did not realize that you had answered me.
when I say frozen is that the led indicators stay on, but you can not change the status, when pressing the buttons nothing happens, when pressing the keys no sound is produced, all is frozen although the keyboard is still on,

until a reset is made, turning the keyboard off and on again.

I bought the mauritron manual, but the information that comes about the circuit cards, is very poor to fix the cards. At this moment, apparently the problem is found in the OP1 circuit board, and the symptom, more clearly, is that if you press more than 4 keys of any combination no matter what octave or if it is on the upper or lower keyboard or a mixture of them, the frozen effect is given immediately after releasing the applied key combination, at that moment a tiny "clip" sounds in the speakers and it immediately freezes, making tests I have found that this only happens when the control key "combi" (upper combi or lower combi) in the assembly section

is activated.

, thank you for your answers, I keep working if you have some idea please let me know, and very important, ... if you have better information about the cards or some glossary that helps me identify what the names of the signals mean, such as: SYW, LV1, LED1, ETC. that will be help very helpful.


Greetings.