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.

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 for the tips. I will check those things out.

Hi - my ESQ is exhibiting the exact same key on/off behaviour except with the upper 5 keys (they are part of a group). I have gone over the keybed and tested for shorts but nothing came up bad. I’ve also tested all the diodes in the keybed but those seem ok as well. Recently I reflowed the solder on the motherboard keyboard cable header connection and the controller IC socket. I also removed, cleaned, and reseated the IC. Still having the same issue.

I’m still waiting on a new ribbon controller and in the meantime have found a complete donor motherboard which is on the way. I’ll pull the keyboard IC from it and see if that makes the difference. If nothing else having the spare motherboard is good long term insurance in case any other components need to be harvested.

Will report back when I have some updates!

fyi, You can check the ribbons easily using a multimeter and two small pins or paper clips. This method works just fine and potentially saves you unnecessary expenses.

Simply pull the ribbon in question out of the keyboard and test the connector pins sequentially. Takes 2 minutes.

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Thanks for the tip. I already rang out the ribbon, it’s all good. I really think
it must be the keyboard IC that is bad. This unit will receive MIDI notes from another keyboard and all notes will play but if I try to send MIDI from the ESQ to another synth, the same 8 notes are dead.