[sdiy] Arp Quartet Constant Sound

[Jacob Watters]

I have an Arp Quartet that is making a constant sound of the B note near
the middle of the keyboard.

It only makes the sound when Strings or Brass are turned on, and does not
do it for Organ or Piano.

Also, the tone stops when the Percussion in the String section is turned up.

The key contact is not stuck to the power rail - so the key is not
physically stuck in the ON position. Also, I can hear a very slight volume
change in the sound when I press the same B key on the keybed. I think that
this indicates that the envelope is being triggered properly.

I tried swapping the B divider chip with the one next to it, and the noise
continued on the B. Removing the chip entirely stops the noise, but then I
have no B notes.

The service manual is not the easiest to read. I think that I should be
looking for either a short on the board with the keybed and dividers, or
something on the F Board where only the strings and brass are filtered.

Does anyone have experience with this string machine? Can you maybe point
me in the direction of what to check?


Thanks for the help.

Best regards,

*Jacob Watters*
JacobWatters.com <http://jacobwatters.com/>
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