ESQ-1 keys 33-40

I have an ESQ-1 that exhibits the following symptoms:

ESQ-1 Keys 33-40 will play but will sustain until the keyboard is turned off and turned on again.

The ESQ-1 will not send out MIDI for those same 8 notes.

Conversely, an external MIDI keyboard WILL play those 8 notes on the ESQ-1 without them getting stuck.

Following - I have the same issue with the upper 5 keys on my ESQ-1. All research points to lack of connection to the keyboard controller IC or the IC itself is failing.

I’ve disassembled the keybed and cleaned all contacts and verified continuity with the traces to the header pins. I’ve cleaned and re-seated the keyboard to motherboard ribbon cable with no change. I’ve ordered a new keyboard ribbon cable to to rule that out. Following that I’ll pull the motherboard and reflow the header pins and IC socket pins.

If none of that works it’s likely a failing controller IC which is unfortunate as those are basically impossible to find on their own these days. I would have to live with the loss of the top five keys at that point (trigger via MIDI if I had to).

Keen to hear how you go with yours.

Thank you digix for responding to my post. I have more details about the behavior of my ESQ’1.

  1. When I first turn it on, the 8 keys in question get stuck and produce
    sound after I release the keys.
  2. If I hold down at least 8 other keys, the stuck notes will stop
    sustaining. (Because the ESQ’1 has just 8 note polyphony.)
  3. Then if I push down on any of the 8 bad keys, there will be no sound.

Does this fit the description of a failing controller IC?
I would love to get your take on this.
Thanks.

Of course check the ribbon cables first. I would then check the contact springs and the circuit board on the keybed itself. There could be a dry solder crack or bad capacitor/resistor, etc. Look for corrosion on the circuit board also. Dry cracks are common and can give a “partial” circuit connection, then quit.

I had this happen on my Mirage DSK-1 and it was corrosion from a past spilled drink or something. I had to solder on a few jumper wires. You can test continuity with a multimeter of course.

Thanks,
Johnny