If anyone would like to see it, here is a PDF of the exposure mask I made up for etching the Casio SK-1 MIDI Mod PCB: https://nuxx.net/blog/wp-content/uploads/2026/06/Casio_SK1_MIDI_exposure_mask.pdf

Cut errors in 2nd Run…
(Click for full size)

As a bit of an update, I spoke with the customer service rep for my account over at MaverickLabels.com. He apologized for things, thanked me for the scans (I figure they are the only clear way to point out the errors) and said that the job will be re-run tomorrow, and they will be sent out via UPS Next Day Air.

So, I guess I’m waiting until Friday. As long as the labels on Friday look fine, I’ll be happy. I think a combination of waiting too long to eat along with bad traffic made me a bit grumpy, to say the least.

I think I’ll go clean up my workspace downstairs… Since synth things are wrapping up (for now), it’d probably be a good idea to bin the spare parts and get everything in order again.

So I’m thinking about a new project to work on, and I’ve got a fairly ambitious idea: Build A Drum Sequencer

After looking around and talking with via some forums, I’ve come to realize that there really is a lack of any sort of stand-alone step sequencer for use with drums, especially in kit form.

Thinking about it, I believe that I could probably take the digital part of the x0xb0x, add or remove LEDs and buttons as needed, then rework about half of the software so it works a bit differently. Using a few resistor networks I think I could simplify the panel a bit too…

So, I think there’s a couple of (major) steps to doing this. Then I could even sell the thing in kit form. Those steps are:

· Settle on a feature set and the buttons and LEDs this will require.
· Rework the x0xb0x schematic to reflect this.
· Design a panel layout which will be usable, fit a readily available enclosure, and will allow the parts to fit around each other on the PCB.
· Order some sample PCBs and build a prototype.
· Rework the x0xb0x software to do what is needed.
· Look into selling either PCB sets w/ parts lists or full kits.

I wonder if this is within my abilities.

I think as a test I may to write some new x0xb0x software which will sort of implement this functionality, just to see if I can manage that part…

Tonight I got the modifications to my PAiA FatMan all implemented. Unfortunately, after powering it back up I realized that it wasn’t quite working any more.

When I press a key, I’m getting a single shot of sound for each key press, in a way which almost sounds to be as if the synth is generating a single wave and then stopping. Both VCOs are doing this.

The VCF still seems fine as does the VCA, and I’ve triple-checked everything. I even went so far as to individually remove all the lines which actually implement the various modifications in order to rule them out.

My current thought is that when attaching the wires to the back of the PCB I fried both of the new CMOS 555’s which I put in. My thinking is that non-functional timer, things can’t repeat, etc… It’s also the only thing I’ve touched since I had it working last night.

I’m fairly confidant that all the digital stuff on the board is still good, all the way through the midi -> cv part of it. The MIDI light blinks, the gate LED goes solid whenever a key is held down. Also, the VCF and VCA change the sound appropriately when one fiddles with the knobs. If I crank the release on the VCF way up, a sustained sound is heard. Even the modifications I made seem to be working, just for a very brief period of time.

Fortunately I had ordered four 555’s (originally only used two) and I’ve got some DIP8 sockets laying around, so tomorrow I’ll just replace them with socketed parts. I’ll also do one, test, then go from there…

I really, really hope that is the problem. I’d love to hear ideas if any of you think it could be something else. The schematic can be found near the end of this PDF.

However, the only points I did anything with on the board since it was working last night are the 555s, part of the VCF to provide audio in (soldered to a pin of an IC), and half of a resistor, so the 555s will be the first to be swapped tomorrow.

Oh, and it sounds really, really cool with these modifications. Much improved over the original.

UPDATE: Gur. I’m an idiot. Of course you’ll just get a burst of sound with ‘sustain’ in the VCF turned all the way down. Guh. Yeah, it’s working fine… I just need a new EPROM with new software on it to work around the FATMOP v1.8 (or whatever) MIDI bug.

After another night of working on synths, I have something to show for it. Tonight I got the PAiA FatMan I am rebuilding (photo gallery retired) working, and as a test I had my x0xb0x triggering it, and both of their audio mixed together.

Listen here: http://www.nuxx.net/files/x0xb0x_and_fatman.mp3

Also, flying wires to a front panel are a pain in the ass. Photos later of why.

Error in my x0xb0x Panel Overlays

Well, this is good. I’ve been in touch with MaverickLabels.com about the error in the printing of the x0xb0x panel overlays. I’ve been told that the reprinted panels will either ship today or tomorrow. This makes me quite happy, because hopefully I’ll have the synth finished by the end of the week. So, while there was a problem with the printing, that company is definitely doing a great job getting it sorted out. I feel a lot better about this all now.

Now, just two more synths to finish… Well, that’s before the 9090 project (and this will be a HUGE project) begins. More on these other two later.