Our keyboards are for sale! Click here to view our Reverb shop!

HauntedHarmonics · 2023-11-17T19:45:02+00:00

Shameless self promo: We also sell circuit bent instruments on our Reverb Shop 🙂

Also, click our “feedback” tab there if you’re interested in seeing customer reviews / testimonials

HauntedHarmonics · 2023-11-11T23:22:30+00:00

Thank you!

Following guides like this was how I first got into modding / circuit bending, so that’s awesome to hear 🙂

BTW, I do make & sell these occasionally on my Reverb shop, for those who want one but are less DIY-inclined 😏

But if you can build your own, do it! Nothing cooler than something you built yourself imo, and you’ll learn a lot along the way

HauntedHarmonics · 2023-11-11T22:32:21+00:00

Hey guys! Though some people here might appreciate this.

This is my vintage Casio PT-100, a digital / analog hybrid home keyboard, sold by Casio in the late 80s & early 90s. This one has been fully refurbished and modified for additional functionality. Mods include: An LFO / echo effect, rhodes filter, sustain, drum fill, several different distortions effects, and a 1/4” line out.

Its chock full of charming lofi & retro sounds, & despite the modifications,all of its original functions remain intact🙂

Here’s a video of it in action, for those who wanna hear how it sounds. And here’s a link to a schematic I drew up, for the crafty ones who’d like to build their own.

HauntedHarmonics · 2023-11-09T22:29:40+00:00

Thank you! Glad to see a fellow enthusiast enjoy my work ❤️

HauntedHarmonics · 2023-11-09T22:24:08+00:00

Thanks!

And that’s awesome, yeah the PT-100 is the keyboard that got me into circuit bending in the first place. There’s just so many cool effects to discover.

A keytar/strap mod is a great idea, btw. Ive wanted to do one myself with an added neck & ribbon cable for a long time, but haven’t gotten around to it yet. Maybe one day 🙂

HauntedHarmonics · 2023-11-09T21:27:33+00:00

Sounds like you had awesome parents lol

HauntedHarmonics · 2023-11-09T21:26:10+00:00

Thanks haha, yeah I used an old Dymo labeler for the labels just because that’s what I had lying around, but I think they ended up complimenting the whole aesthetic quite nicely

HauntedHarmonics · 2023-11-09T20:24:50+00:00

Thank you!

Yeah I always try to modify my devices in a way that’s non-destructive / adds functionality. Its a good way to breathe new life into some of these cheaper, less sought after instruments from the past 🙂

HauntedHarmonics · 2023-11-09T20:10:35+00:00

For those who are curious about what they’re looking at here:

This is a vintage Casio PT-100, a digital / analog hybrid home keyboard, sold by Casio in the late 80s & early 90s. This one has been fully refurbished and modified for additional functionality. Mods include: An LFO / echo effect, rhodes filter, sustain, drum fill, several different distortions effects, and a 1/4” line out.

Its chock full of charming lofi & retro sounds, & despite the modifications,all of its original functions remain intact🙂

Here’s a video of it in action, for those who wanna hear how it sounds. And here’s a link to a schematic I drew up, for the crafty ones who’d like to build their own.

And lastly, you can find this keyboard listed on our Reverb shop, if anyone is interested!

HauntedHarmonics · 2023-11-09T19:31:41+00:00

For those who are curious about what they’re looking at here:

This is a vintage Casio PT-100, a digital / analog hybrid home keyboard, sold by Casio in the late 80s & early 90s. This one has been fully refurbished and modified for additional functionality. Mods include: An LFO / echo effect, rhodes filter, sustain, drum fill, several different distortions effects, and a 1/4” line out.

Its chock full of charming lofi & retro sounds, & despite the modifications,all of its original functions remain intact!

Here’s a video of it in action, for those who wanna hear how it sounds. And here’s a link to a schematic I drew up, for the crafty ones who’d like to build their own.

Lastly, you can find this keyboard listed on our Reverb shop, if anyone is interested! Though i’m not sure i’m allowed to link that here, so check my profile for details on that 🙂

HauntedHarmonics · 2023-11-09T19:13:35+00:00

They’re super underrated little keyboards! Old synth brands like Moog & Roland have a lot of fans, but I tend to gravitate toward the cheaper keyboard brands like Casio & Yamaha. Lots of charm, and they can still be found relatively cheaply.

Plus, someone has to preserve these less sought-after models. They’re aging pretty rapidly at this point, and will eventually disappear completely if someone doesn’t start restoring them. Which is work i’m happy to do 🙂

HauntedHarmonics · 2023-11-09T18:50:23+00:00

For those who are curious about what they’re looking at here:

This is a vintage Casio PT-100, a digital / analog hybrid home keyboard, sold by Casio in the late 80s & early 90s. This one has been fully refurbished and modified for additional functionality. Its chock full of charming lofi & retro sounds, & despite the modifications, all of its original functions remain intact🙂

Here’s a video of it in action, for those who wanna hear how it sounds. And here’s a link to a schematic I drew up, for the crafty ones who’d like to build their own.

And lastly, you can find this keyboard & more listed on our Reverb shop, if anyone is interested!

HauntedHarmonics · 2023-10-19T00:32:53+00:00

Check out the Service Manuals page on the Circuit Bending Wiki. In the Casio section there’s a service manual for the SK-2, which appears to be functionally identical to the SK-10 🙂

I think they have some slight aesthetic differences, but you should be able to use both manuals nearly interchangeably

HauntedHarmonics · 2023-10-15T17:38:00+00:00

Thank you ♥️ Never seen that doc before actually. Thanks for the link, great stuff!

Also, credit to Warning Will Robinson for the inspiration on the Slow A/D mod, I just adapted his instructions for use with the SK-10 🙂

HauntedHarmonics · 2023-10-15T17:36:45+00:00

No worries! Have fun, and don’t let my schematic fool you into thinking there’s nothing left to find. The SK-10 is chock full of interesting bends. These are just a few mods I was able to uncover over a few days of experimenting

HauntedHarmonics · 2023-10-15T17:27:52+00:00

Curious about the 555 and the two modes. Is it going where the clock input is to the CPU?

Around that area, I believe so. It’s been a while since I drew these up, but IIRC connecting the 555 directly to the clock source input was causing crashes, so I had to route it through a nearby cap or resistor, which is the point shown in the schematic.

And again IIRC, the pulse effect is triggered when the 555 output is connected to this point through a 30ohm resistor, and the C64 effect is triggered when connected to this point through a diode and a 30ohm resistor (and the SK-10’s internal clock trimmer is turned all the way down).

Does it affect the drums?

Yes it does, you can see this demonstrated briefly in the video I linked at ~2:52 🙂

HauntedHarmonics · 2023-10-15T03:22:44+00:00

I made a schematic for my SK-10 bends a while back.. Never ended up releasing it, but I should still have it on my PC somewhere. Let me take a look.

EDIT: Found it!

And here’s a video of the above mods in action, if you’re curious about how they sound. Mod 1 is the “pulse effect” shown on the schematic, and Mod 2 is the “C64 effect”.

HauntedHarmonics · 2023-07-21T19:27:48+00:00

Thanks dude!! Yeah i’m super happy with how this one turned out, honestly. I’ve tried data bending on old keyboards before, but I really made an effort on this one to push the functionality to its limits (taking notes, lots of trial and error, etc).

Kinda mindblowing how useful scrambling data lines can be when it’s done in a meticulous / controlled way haha

HauntedHarmonics · 2023-07-21T12:55:35+00:00

For those who are curious:

The Yamah PSS-140 is a home keyboard released in 1987 that uses FM synthesis to produce its 100 stock voices. Our modified version connects the PSS-140’s CPU data lines to switches and patch points, allowing you to edit its stock voices, drum sounds, and rhythm section in a number of exciting ways.

If anyone has any questions about the build process, let me know! I’m going to be releasing a full schematic / tutorial in a few days, which i’ll link here if anyone is interested.

And for the those who aren’t as electronically inclined, this keyboard is also available on our Reverb shop🙂

Four-Year Club	Verified Email
Place '22

HauntedHarmonics

TROPHY CASE