M-Audio keystation 88es specific electronic advice please?


Novice Member
I’m hoping there will be somebody somewhere out there who has intricate board level knowledge of the key station 88es.

It’s a long story.
I ended up with an 88es with no mainboard.
It took just over 2 years for me to finally locate a new mainboard. I was very excited about this, I’d almost thrown the keystation out only weeks ago because I was sick of looking at it in its partial form.

Anyway the board arrives and the physical fit is perfect. This is an 88es mainboard going into an 88es.
All the connectors are different.
My 88es has much smaller connectors than the mainboard I bought. The keybed ribbon, the wheels, the octave buttons, all different.

In my wisdom, I made the assumption that they had simply changed the connector pitch.
This seems to be true for two of the connectors, I made up some adapters, pin for pin, and the wheels and volume slider seem to work. Thought that was the winning formula.

But no, the octave switch board on my 88es has a half dozen extra pins than that of the replacement board. Turns out my 88es has dual colour leds on the octave switches, that the replacement mainboard doesn’t cater for. But I’ve borrowed the octave switches from my keystation 49 and that works fine on the 88es mainboard.

I thought the last of my issues would be the keybed connector. And it does look like although the connector is physically smaller, it should be the same pinout. Again, no.
I made up an adapter for the keybed and the key positions are all over the place, half the keys don’t respond and the other half just give me random tones.

Nuts and bolts is I think I bought the wrong revision of mainboard, an earlier one than I needed for my 88es.
Is there anyone out there who knows the 88es to this extreme?

I’ve spent all day reverse engineering just the octave switches and making up adapters, and I just can’t see why they would change any pinouts, but it seems that’s the case.

Sorry, I know it’s a long story and a long shot too.


Novice Member
A little more progress. This photo shows the first issue I was up against here, the OEM octave board in my 88es had totally the wrong connector and number of pins.
IMG_0619 (1).JPG

Having reverse engineered the one I found that did fit, from a keystation 49, I've made up my own octave board so that I can return the one I borrowed.
As I was able to choose the connector I made this fit the mainboard perfectly, and it responds on my DAW. One problem solved. Crude, but it works.

Next the connection for the wheels. I'd assumed this would just be pin for pin on a larger pitch, and I was correct. This is the adapter

It now fits fine into the mainboard and registers on my DAW. Two problems solved.

Luckily the volume slider was a straight fit and I havent had to modify that.
This is the problem I'm now left with. The keybed connector has the same number of pins, the same connector style (just a smaller pitch).

Assuming it really is just pin for pin, I made up this adapter.

And that is where my progress ends.
The two black plugs go to the mainboard, but at that point the keys are all jumbled up.
I've no clue how the diode steering works, so now I'm at a loss.


Novice Member
This is now fixed and working. For anyone else’s interest, the connectors are all pin for pin just on a different pitch. Except for just one connector...
The later octave board has dual colour led indicators which is why there were extra pins on the connector. Early mainboards don’t support that.

Instead of relying on adapters I’ve hard soldered ribbons between the boards now and although it’s a nuisance if I ever need to strip it again, I hope I won’t have to. All the keys are now working and in the right order.
Drop me a line if you are reading this having googled with the same or similar issues.

The latest video from AVForums

Podcast: The Best TVs and Projectors of 2020, plus AV, TV Show & Movie News & Reviews
Top Bottom