Circuit Bending Challenge

On October twenty-eighth two-thousand seven, a prestigious challenge was put forth. Thrift stores raided, fingers moistened, soldering irons heated, and toys violated. When the solder smoke finally cleared, only one could stand victorious with their ears covered. This is the story of my part in that challenge….Ok, enough with the epic narratives.

The challenge was to pick up a toy, bend it, and document it on the web all in one day. I was interested in the challenge as soon as I heard about it, and figured I would double up the fun by making an event of it. I invited some friends over to have a “Bending Workshop” on “Circuit Challenge Day” (soon to be nationally recognized). Three of them thought it sound like a slightly strange, but fun idea, so plans were laid. Continue reading “Circuit Bending Challenge”

VSS-30 Tutorial

The video above is of my most recent bent VSS-30 that uses a 12 point switch bay using 2 way center off switches. This is my documentation on bending a Yamaha VSS-30. This ultra sampling keyboard has some really awesome capabilities on it’s own. I got this info initially from one of the bending forums, but I don’t know who to credit, so thanks whoever you are! I know some folks haven’t bent their VSS yet due to fear of frying, so hopefully this guide will help you.

*Note*When I first did this bend, I avoided the 2 red dots (power and ground). I’ve since bent another VSS-30 and used these points with no ill effect. As always, bend at your own risk */note* The blue dots in 2 rows are the points of the sampling chip. The blue dots in a straight line going up and down is where the points connect to the big chip. There are 2 pins on the sampling chip that connect to each other (yellow line), so that gives you 15 points to bend. I chose to use 12 of those points for symmetry, and I chose to use an RCA style patchbay. I found that Tablebeast did a layout on one of these that I really liked, so I did this one the same way. You can see/hear his Here. I chose to solder to the points that were up and down in a straight line for ease of bundling.

Here’s the board wired up.

Here’s the area where I chose to put the RCA connectors. I checked, double checked my measurements. The pencil lines you see are where there’s a plastic support on the inside of the case.

Here’s the installed RCA jacks. Not absolutely perfect (need a drill press for that), but lookin’ pretty good IMHO.

Here’s the front side of the sample crusher for those that don’t have one already (keep an eye out cause if you don’t have one you’ll want one!).

Now let’s test it. Record a sample, and play it to make sure it recorded decently. Now plug in a patch cable to two of the RCA jacks. You should get all manners of distortions, tremolos, and all kinds of other effects on the sample. Layer the bends on top of each other with more patch cables, and you can completely change the sample so that it sounds nothing like it originally did. I used the loop feature built into the VSS to make some really awesome loops with the bent samples.

There’s an audio sample of this on my sample page.

Disclaimer:

As always I take no responsibility if you happen to touch the wrong point on your VSS, and kill it. I found this bend to be very reliable, and not to difficult to do if you take your time.

PSS-270, 170, 140 and SHS-10 Tutorial

After some major diggin’ for info I found that no one had a specific guide for bending a Yamaha PSS-270, so I decided to make one. Credit to Sean “audioid” (myspace.com/audioidbentaudio), and Paul from circuitbenders.co.uk for the info on this bend. This bend involves cutting data lines that go from the FM synth chip (YM2413) to the main chip (XC194A0). The pins on the FM chip that go to the main chip are pins 2, 3, 4, 5, 6, 7, 17, and 18. You cut the traces, and then solder wires on either side of the cut. Take the pair of wires from one cut, and solder them to a switch, and this will allow you to turn the flow of data on and off.

This is a picture of the board flipped over. I have the FM chip out-lined in red, and you can see the big chip under it.

 

 

 

 

 

 

In this picture I have the solder points from the FM chip marked in red dots, and the blue dots are where they go to the main chip. Ignore the green dots. The black line is where you *carefully* cut the data lines. I used a volt meter to check and make sure that the lines no longer had continuity.

 

 

 

 

 

I’ve indicated the FM chip in this picture.

 

 

 

 

 

 

 

Here’s all 16 wires in place. Some people recommend drilling very small holes on both sides of the trace cuts, and putting wires through them, or scraping the coating off so you can solder on it. I just soldered the wires onto the pins of the chip, which can be dangerous because you run the risk of overheating it. I used a pair of wires that are the same color for each connection to make wiring up the switches easier.

 

 

 

 

I’ve got the board back in place, and the wires bundled up nice and securely.

 

 

 

 

 

 

Now all the switches are wired up, and we are ready to button her back up.

 

 

 

 

 

 

I found the most room for the 8 switches on the right side of the keyboard. Just measure and drill carefully, and it will come out looking great.

 

 

 

 

 

What the Bends do:

Each switch now controls the flow of data from the FM chip to the main chip. Turn the PSS on and select a patch (let’s pull up #89 “ghost”), I usually play some keys(don’t know if you have to do this or not), then turn some switches off , now select a different patch, and turn the switches back on. Now try playing the new patch. If it went well some of the data from the all patch got held up, and then inserted into the new patch making a totally different sound. Sometimes leaving the connections off will change the sounds also. I’ve noticed them some of the bent up patches will only work when multiple keys are played. I’ve heard that this will effect the drums as well, but I haven’t gotten it to do much with them as of yet.

Getting some good sounds out of this takes some tinkering, but it’s worth it. The only downer is that it’s hard to reproduce the sounds that you get, so if you have a good one be sure to grab a sample while you can. Using the keyboard this way can corrupt the data to the point where the chip crashes in a noisy mess, but all you have to do is turn all the data connections back on, and turn the keyboard off, then back on. All the data connection switches have to be on for the keyboard to work “normally”.

John from Bentpedals sent me these photos of a PSS-140 that he did up using this same mod. The main chip is colored in red, the FM chip in blue, ignore the yellow.

 

 

  

 

 

I did the mod on a PSS-140 for Mjm using the info that John gave me. This is what he had to say about it “endless amounts of fun. endless unpredictable possibilities. i don’t want to stop messing with it”. Here’s some photos of that.

Wesley did the same mod to a PSS-170, but his link seems to be dead.

 

 I’ve successfully done this on a Yamaha SHS-10 Keytar , along with some other circuit bends. Tinsoldier sent me a diagram of his circuit bent SHS-10 which I will post here. I can’t comment on it at yet because I haven’t had the chance to try them myself.

 

 

 

 

 

 

Disclaimer:

As always I won’t be held responsible if you try this bend and your Yamaha get’s hurt. I’ve done a lot of playing with this keyboard, and it seems real solid to me. This bend works on some of the other PSS series keyboards (like the 140) with a similar chip setup, but since I’ve only done a 270 and 140 so far I can’t gurantee it will work on all of them.

Furby Bending Tutorial

Since I’ve been asked many times about bending furbies I thought I would make this guide to help those that would like to give it a try.

This furby is in the typical shape I find most of them in. Let’s take away his dignity further by striping him of his fur.


This lump on his bottom side is where there is a strap tie holding his fur on. Cut this, and pull the tie strap out.
Furby 3
Roll his ears back and cut the threads holding them on.

I usually roll his fur up along his body so we can expose the screws holding his face piece on. Remove the screws, and there will be some hot melt glue attaching the fur to the top of his head. With some light tugging the fur should free and then you’ll have your very own naked furby. Remove all the screws from the carapace, and it will come apart in 2 halves.

See, look at how liberated he is to be freed of that cumbersome fur.
Furby 6
You have to take off the speaker/tummy switch to be able to tilt his battery compartment over, and get to the circuit board underneath. This is also a good time to add wires to the speaker for your output jack.
Furby 8

I’ve found a stable glitch, and loop bend that stem from the same common point. I have the common marked in red, the glitch in blue, and the loop in green. Your mileage may vary from one furby to the next. On this particular furby I used a 47 ohm resistor in line with the glitch wire to make it a little more stable. I’m sure that there are more bends in a furby, but I haven’t dug to deep because I’ve heard that these fry easy.

The bending has changed him some how….

I normally run the bend wires along the right side of the furby up to his head. There is a small area on the back of a furbie’s head where you can drill a hole, and run the wires out to a control box. I normally set it up with a switch for the glitch bend, a normally open push button, and switch for the loop. You use the push button to find a loop you like, and then flip the switch to lock it in.

I’ve had a lot of people ask me about the way the loop section is wired, so I made up a nitty gritty diagram in MS paint. I still have the wires colored the same as in the circuit board diagram. Basically what’s happening is that you have the same connection wired to 2 different kinds of switches.

Disclaimer:

As always I won’t be held responsible if you try this bend and your Furby get’s hurt!


I’ve done quite a few furbies now, and I always try to make each one unique to the others. I’ve played around with decorating them in strange ways, and I built one that has all it’s bends controlled by an Atari style joystick. I’m going to post some pics of a few of these on this page.