I’ve only gotten 3 bends fully wired up on the PSS-460, because I’ve been having too much fun playing it.

The bends so far are two distortion bends that also tend to have input on other bends when they’re turned on.

The third bend is one of a group of bends that together make up what I’ve dubbed ‘Ornery Mode’. They cause the cpu/sound chip to ignore keyboard input, and react unpredictably when not ignoring input. The result can be bizarrely ambient, but is quite Aleatronic.

Sample: 28 megs, 20 minutes, 192kbps

In part 2 I examined some bend points. There were so many good ones on the sound chip, I’ll spend some time connecting the chip to an external breadboard to make adding more bends easier.

Preparing a ribbon cable

In the past, I’ve done several bends where each bend gets a wire to the pin. Instead, I’m going to attach a ribbon cable to each side of the sound chip. Conveniently, ribbon cables are available for cheap - I’m using a cable for a floppy drive.

First, cut off the connector. Then, count out twice as many wires as you have pins (I have 12 pins per side, so I’ll be using 24 strands of the cable) and tear off the extra. It should tear easily.

Next, strip the odd-numbered wires (counting the red-marked wire as 1) and cut the even-numbered wires shorter. We won’t be using the even-numbered wires; they’re just there to act as a spacer. Don’t strip off too much insulator; you only need a couple millimeters of bare wire to solder a joint and keeping it short will reduce the chance of (unwanted) short circuits.

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I obtained a Yamaha PSS-460 on ebay a few months ago, and am starting a series of posts as I bend it.

The PSS-460 is a good example of an 80’s keyboard. It has a separate CPU and sound synth chip, has a drum synth and a headphone jack. It can be both battery-powered and powered via a 12 VDC jack.

Inside the case

	Up top, we have the battery holder (will cut and re-attach the wires later). On the left and right are the speakers. Between the speakers are a pair of circuit boards, one brownish and one green, one mounted above the other with standoffs and screws. At the bottom is the backside of the keys, conveniently colored brown as well. In fact, both brown boards are just key/button mounts (one for the keyboard, one for the control panel) with pullup resistors and ribbon cables. This leaves the main green board, which is the one most interesting to us.
Gaining access to the main board
	First, we have some shielding/padding to get through. This is here to prevent interference from below the device from affecting the main circuit board. For now, I’m removing it, but will add it back when I’m done.
	After removing it, we get a clear view of the back of the main board.

Getting started on a new project, the result of spending too much time at Goodwill, staring at keyboards and wondering if they’re worth buying. I’m trying to collect a list of devices that are bendable, starting with keyboards. I’m sticking mostly to the 80s-era keyboards, like the casio sks and yamaha psses, though if I stumble across a bent keyboard that’s more recent and I think sounds good or shows potential, I’ll add it.

There’s a lot of info missing, like years the instruments were produced, whether they’re polyphonic, etc, but I’ll fill it in as time goes on. If you spot some I’m missing, particularly if you have links that include images and/or samples, drop me a line. I can use all the help I can get.

I know I have more basic electronics articles to write, but I have other things in the docket at the moment:

- What’s in a black blob? I’ll be taking apart a black blob device to show, but I’ll explain what makes it different from the 80s devices beginner circuitbenders love. (Hint: it’s not the availability of bend points that make them different.)
- What can you do with a black blob? This one should have samples, as I just got a mixer that will aid in recording. Hopefully this will show the depth to which black blob devices can be modded, even when limited to clock speed modifications. Suddenly, all those <$5 noisemaking toys at the thrift shop start looking good.

And the basics:
- Need to write up series vs parallel and path of least resistance, especially considering how complicated the clockspeed circuit mods for a black blob device can get.

Got a question? Have an article suggestion? Want to know more about something? Let me know.

Added a new circuitbending article on building an Advanced Probe.

I’ve not actually built one fully - I actually use a prototype breadboard and temporarily solder leads directly on to the PCB. This works great if you can look at a board and know where the V5+ and GND pins are by their location or pin shape (on chips). If you don’t have that kind of knowledge (I’ll write it up later, I promise), or just want a good system for finding bends, the Advanced Probe is a good idea.

I came up with the idea initially when reading Rheed Ghazala’s page on Cautions, which lists warning signs like sparks or batteries heating up. In my opinion, if you’ve reached a point where the chip is getting hot or the batteries are draining so fast they’re getting hot, you’re already potentially damaging the instrument, possibly in a subtle way you won’t notice until later. Just checking the voltage difference before making the connection will prevent this from happening.