Rotato

Today it's the MC-303 back on the bench.

After I had initially repaired it, I noticed that the rotary encoder was a little skippy. It would sometimes miss steps, go backwards, etc, which indicated that it likely had some contact issues inside it. So, apart it comes.

We'll need to remove this happy little camper from the board.

And luckily this unit is old enough to have delicious leaded solder, which slurps up so nicely.

To properly clean the contacts, we'll need to open it up. They're not exactly designed to be opened, but it's relatively safe to do once or twice.

With the limiting factor being how many times you can bend these tabs back and forth before they fatigue and break off.

But given it's lasted this long before failing, it'll probably be a good while longer before it fails again. and needs another disassembly.

Inside we have three contacts and a spoked metal disc. One contact rides around the solid part of the disc making constant contact, while the two others ride around the inner and outer spokes respectively, making contact 90 degrees out of phase with each other.

At least that's what they're supposed to do when nothing's getting in their way.

Hmm, what's this? Zoom, enhance!

Well that's no good, there's a little flake of plastic sitting on the back of one of the contacts. If that got between the contacts and the disc it wouldn't function very well. I wonder where it came from?

Yes, I wonder indeed. It looks like a thin ring of plastic was overmolded onto the outer circumference of the spoked disc, and it has over the years cracked and broken away. Well, that explains things, better clean out the shrapnel.

That's looking much better. Now it's just a matter of slathering up the shaft with some friction grease and getting things back together.

And together it goes.

As does the rest of the machine.

And I'm happy to report that the encoder now works perfectly.

I do have one other task on the plate for this unit...

But it will have to wait for another day.

If It's Worth Doing Once

So the time has come to crack open the MPC1000 again, hopefully for the last time.

The replacement pad sensor sheet came in to replace the one with the unfortunate manufacturing flaw. So, let's dig in.

The top case comes off in the usual manner, and the pads just pop right off, revealing the sensor sheet support bracket underneath. With 4 more screws it can be flipped over, and we'll release the flat flex and then unscrew the adapter PCB to free the bracket (and its attached sheet) from the unit.

A little preview of the before and after, the new pad sheet doesn't have the unfortunate manufacturing defect cutting through the trace for pad 4.

But before I put the new one on I have to peel the old one off, and it's properly stuck down. Slow peeling and cutting the adhesive with a hobby knife is the way to go here.

And after about 20 minutes of that it's off.

Or mostly off, at least, there's still plenty of adhesive residue left that we really need to get rid of so that the new sensor sheet lays flat against the bracket.

To deal with this I opted to soak the bracket in d-limonene, and the cheapest source of that I could find was Zep citrus degreaser concentrate.

I managed to only spill a little bit on my toes, so I now have very clean toes and an unusually clean spot on the floor of my car hole. Could be worse, I guess.

I let it soak for about 40 minutes, then it was time to go at it with a scotch brite pad.

The fact that the adhesive was now orange seemed like a good sign.

And it was a good sign indeed. Just a little bit of scrubbing with the pad and some water peeled the adhesive right off.

So that was a lot less work than the first time I tried.

After a rinse and dry the bracket is clean and very grease-free, so it's time to reassemble.

Peeling back half of the backing paper gives you something non-sticky to hold onto while you carefully position the sheet.

And once it's lined up, you just pull out the rest of the paper and smush it down.

Then plug it in.

Which is a bit tricky since at least this particular revision of the board doesn't have the type of connector with a release mechanism, so you need to use some force to jam it in.

Anyway, reassembly happens.

And we use the pad calibration screen in JJOS to check our work.

And it looks like luck is on my side this time, all of the pads work!

I guess now I just have to figure out how to use this thing.

A Chorus of Angels

Not everything I buy comes with the "for parts or repair" discount. Sometimes I find a creampuff at a really good price, and that's where this Boss RCE-10 chorus effect enters my life.

Despite being manufactured somewhere between 1985 and 1990 or so, this box was almost completely fresh off the production line, with only a few tiny scuffs on the underside of the front plastic. I would almost be surprised if it was ever even used in anger.

Anyway, not much more to say about this one since it worked out of the box, but it's a nice unit to add to the Micro Rack stack.

The Electric Slide

So one thing that my SK-5 didn't come with was all the slider caps. There's three sliders, and only one cap. This isn't really unexpected as these caps are friction fit and tend to go missing over the years.

Luckily I have a 3D printer and just barely enough patience to tolerate swearing at FreeCAD for an evening.

Somewhat unluckily, there's not really a good orientation to print these in, since there's a sort of stem that sticks out the bottom and the hollow feature on the inside where the shaft of the slider inserts, and so on. That means I needed to print with supports, and they ended up a little bit stuck to the bottom.

And so I spent a little time under the microscope with a scalpel trimming away the stuck-on bits of support material that were blocking up the holes.

Even though I made them the same shape on top, the sliders they have to fit onto are actually two different shapes as one is a volume slide potentiometer and the other is a slide switch, so I had to model the underside separately for each.

But somehow, miraculously, they actually did fit first try. So that's cool. Once again they are the wrong colour because I'm not going to keep 300 different cans of spray paint around the house just so I can paint replacement knobs.

This is definitely the type of tiny, detailed part that I really should get a resin printer to print, but I'm being lazy about buying one.

Keep An Eye On It

I've had a dashcam stuck to the windshield of my van for a while now. Well, mostly. Pretty much every summer, at least once or twice per, the heat causes the suction cup to loosen up and fall off, and I have to clean the glass, stick it back up, and wait for the next time it falls.

Unfortunately I don't think sticking it back on is going to work this time.

Luckily I kept the original goodies, which included an adhesive mount. I didn't want to stick it to the windshield because it would have made it a permanent pain in the booty to wash the glass, so instead I decided to just mount it to the dashboard.

This does mean it's now technically upside-down, but the good news is that I don't even slightly care.

Bob's Burgers

This keyboard right here is the Casio SK-5.

Ok I guess technically it's the Realistic Concertmate 650, but other than a bit of RadioShack branding on the silkscreen it's a Casio SK-5.

At its core it's a basic kid's toy keyboard, a rompler that plays back some pretty crusty 8-bit instrument samples (one of which is a dog bark). But like the SK-1, it also includes some RAM that you can record your own short samples onto; either 4 samples at 0.7 seconds each, or 2 samples at 1.4 seconds (or, if you like, one 1.4 second sample and a pair of 0.7 second samples). These samples can then be played back chromatically on the keyboard like the built-in samples, and you can additionally apply an envelope, play them backwards, or set them to loop or one-shot play. You can also trigger them individually by using the 4 yellow-orange pads on the right. The pads on the left are dedicated to a high and low bongo, a lion roar, and a laser gun sound effect that are all baked into the ROM.

Because sure, why not.

While the SK-1 carves out its niche as the first affordable home sampling keyboard, the SK-5 has found its place in pop culture as the keyboard used by Gene Belcher in the tv show Bob's Burgers for doing things like playing fart sounds. As one does.

Anyway, this keyboard usually sells for around $125 to $250 depending on the condition. Because this one had a "for parts or repair" discount I got it for $45. The seller claimed that it was stone cold dead, and would not turn on.

Well, I plugged the power in and it fired right up and worked perfectly.

But that got me to thinking: they probably didn't have the correct power adapter for this keyboard (as none was included) and so they most likely tried to run it from 5 AA batteries. So I stuck 5 AA batteries in it, and wouldn't you know, it was dead indeed.

So I now had two reasons to open up the keyboard. 1: It desperately needed cleaning, and 2: I'd need to investigate the battery compartment for alkaline schmoo.

And when I say it needed cleaning...

It.

Needed.

Cleaning.

Anyway, let's have a look at that battery compartment. The section near the battery door looked fine, but it's got one of those tiny doors where you just slide the batteries in one at a time, so I couldn't see how the other end looked until I took it apart.

The verdict?

Alkaline schmoo, though not too much of it. Plenty of dust and dead bugs too.

And speaking of dust, these PCB switches had picked up a bit of grime over the years.

And the contacts that wipe across them were a tiny bit tarnished.

They're not supposed to be black and sooty, they're supposed to be shiny and silver. Like this.

Anyway, I scooped all the guts out, so the keyboard is almost disassembled enough to clean.

The cardboard on the bottom is glued in place so I'll just have to work around that, but importantly the keys really need to come out so I can clean around that area. To do so, I'll need to pry back the locking tabs on this plastic cover.

And then once it's popped free, the screws holding the keys in place can be removed.

And now I can clean all sides of the keys, because they very much need cleaning on all sides.

And I can clean the case under the keys, for the same reason.

Naturally I'll also be cleaning the buttons. Because yikes.

So into the sink it goes, with a bit of dish soap and borax to clean all the human schmoo off of it.

Scrub-a-dub-dub.

Naturally the battery contact got some special attention with some white vinegar.

Then everything got rinsed and dried off.

And I'm sure you'll be tickled to know that the keyboard now works on battery power.

And I can actually touch it without getting 17 diseases, 8 of which were formerly unknown to mankind.