Tsumara JD21 restoration

[Folderol]

That looks like a nice little display. Where did you get it from?

[jjlonbass]

It interests me to know how the microprocessor is being made to handle that number of inputs - I've never figured that part out!

Most digital systems that feature more than a moderate number of user switches would organise them as a scanned matrix with each switch connecting together a unique combination of row and column.
With this sort of arrangement one could accommodate, for example, 64 switches with an 8 row by 8 column matrix. An explanation of this with a music tech relevant example can be found here. The examples show the columns being driven by microprocessor outputs with the rows as inputs.

John

[Folderol]

It's also done for low res analog controls. In the past, I've used HEF4066 to do this.

[The Elf]

That all looks baffling. One day I need to figure this out to expand the ability of the Arduino toys I make...

[BJG145]

That looks like a nice little display. Where did you get it from?

I asked about this and they pointed out this example on eBay. (They reckon Adafruit are the best, relatively expensive but cheap ones sometimes have faulty pixels.)

[Folderol]

Thanks. I'll have to check my piggy bank

[BJG145]

Received the latest update on work in progress today.

Wiring up the new display, control buttons and USB socket...













...and the hardware rebuild is done.

Just the programming to finish now...

[Folderol]

[BJG145]

This thing is currently still in Wales, where it's undergoing rigorous final testing in the hands of a gypsy jazz guitarist.

Apparently he's finding it a bit of a struggle. But...what do they know?

[resistorman]

Nice restoration! Though it seems a bit large, looks like he's holding a cyber dolphin

[Martin Walker]

Nice restoration! Though it seems a bit large, looks like he's holding a cyber dolphin

Yes, I was a little surprised at how large it was as well

[Drew Stephenson]

Nice restoration! Though it seems a bit large, looks like he's holding a cyber dolphin

Yes, I was a little surprised at how large it was as well

Maybe he's just very small?

[BJG145]

I recently took possession of the revamped JD21. After spending a bit of time with it, I decided to replace the keys. I'm now a connoisseur of arcade-style buttons and nothing less than Sanwa silent will do. Having acquired an LED magnifying glass and fine-tipped soldering iron, I spent this morning swapping them out and wiring them up.



At an advanced level, electronics is like embroidery. Took a few goes to thread the 0.2mm copper wire through the ground connections, but all done now, and playing nicely. Demo next. I'm enjoying playing this with bass patches.

cyber dolphin

I was looking for a Japanese-themed strap on eBay just now, and made an ill-advised snap decision on a secondhand koi carp design. I partly blame Resistorman for this. Oh well. It is what it is.

[resistorman]

I was looking for a Japanese-themed strap on eBay just now, and made an ill-advised snap decision on a secondhand koi carp design. I partly blame Resistorman for this. Oh well. It is what it is.

Fair enough. As long as I get to complain about the exchange rate and shipping for the Sanwa switches!