Repairdown: Disklavier DKC500RW Control Unit

If you’ve been kind enough to accompany me on these regular hardware explorations, you’ve likely recognized a trend with regards to the gadgets that go under the knife. Generally speaking, the devices I take apart for your viewing pleasure come to us from the clearance rack of a big box retailer, the thrift store, or the always generous “AS-IS” section on eBay. There’s something of a cost-benefit analysis performed each time I pick up a piece of gear for dissection, and it probably won’t surprise you to find that the least expensive doggy in the window is usually the one that secures its fifteen minutes of Internet fame.

DKC500RW installed on right side.

But this month I present to you, Good Reader, something a bit different. This time I’m not taking something apart just for the simple joy of seeing PCB laid bare. I’ve been given the task of repairing an expensive piece of antiquated oddball equipment because, quite frankly, nobody else wanted to do it. If we happen to find ourselves learning about its inner workings in the process, that’s just the cost of doing business with a Hackaday writer.

The situation as explained to me is that in the late 1990’s, my brother’s employer purchased a Yamaha Mark II XG “Baby Grand” piano for somewhere in the neighborhood of $20,000. This particular model was selected for its ability to play MIDI files from 3.5 inch floppy disks, complete with the rather ghostly effect of the keys moving by themselves. The idea was that you could set this piano up in your lobby with a floppy full of Barry Manilow’s greatest hits, and your establishment would instantly be dripping with automated class.

Unfortunately, about a month or so back, the piano’s Disklavier DKC500RW control unit stopped reading disks. The piano itself still worked, but now required a human to do the playing. Calls were made, but as you might expect, most repair centers politely declined around the time they heard the word “floppy” and anyone who stayed on the line quoted a price that simply wasn’t economical.

Before they resorted to hiring a pianist, perhaps a rare example of a human taking a robot’s job, my brother asked if he could remove the control unit and see if I could make any sense of it. So with that, let’s dig into this vintage piece of musical equipment and see what a five figure price tag got you at the turn of the millennium.

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