Circuit Bent Sing-A-Long Barbie Karaoke Tape Recorder

My plans for a productive 3-day weekend devoted solely to art-making were dashed by some charitable person who donated a Barbie Karaoke tape recorder to the local Goodwill. Not too long ago I read about circuit bending one of these on Peter Edwards fantastic Casper Electronics site, and I've been on the lookout for one ever since. After buying a stack of fresh batteries and looking over the bending schematics I started poking around the main circuit board and identified a bunch of bend points, mostly around the echo circuit. The Barbie Karaoke has a cheap "echo" feature that when bent creates strange and wonderful noise which are generated once you turn the tape player on. After finding about 20 different bend points I decided to build a separate panel on which to mount the the various components, similar to what I did with the Caisotone. The Karaoke machine would be attached to the top of the panel with the wiring running through holes drilled in the bottom, then soldered to the various components inside the panel. Each wire attached to a bend point on the circuit board was soldered to one of twenty banana jacks, which can then be connected by lead wires to a series of potentiometers. I also added a pitch adjustment (located towards the back of the panel, on the left) and both an input and output jack - another cool thing about the Barbie Karaoke is it has two input lines (one for an audio source like a CD player, and the other for a microphone) so you can plug other stuff into it, such as other Barbie Karaokes.

Some photos:

Partially wired panel with banana jacks, switches, and potentiometers.
Each pot can be turn on & off with it's own switch.

View of circuit board back in place with bend points all soldered up & wires fed through holes drilled in the bottom of the karaoke. The bundled wires at the top of the photo are all soldered to points on the echo chip.

View of bottom of completed panel.
The Barbie Karaoke is attached to the top of the panel with a single screw.

Finished!

Finished view with lead wires plugged into various bend points.

I'm really pleased with how this piece turned out. There are a few other mods you can do, such as adding a variable speed controller for the tape player that involves replacing some circuitry - maybe next time. For now I'm happy to experiment with this as-is:

Circuit Bent Casiotone CT-460

So my latest circuit bending foray is a ca.1987 Casiotone CT-460 keyboard that I picked up at the local Goodwill for 15 dollars. A quick Google search led me to a pdf of the user's manual, and a couple of circuit bending sites and youtube videos. After verifying that the thing still worked (via slightly balky 9v adapter plug; I rewired the battery connection to accommodate a 9v battery & added a kill switch) I pulled the back panel to take a look at the circuit boards. I poked around a bit & found tons of bend points associated with the chip just to the right of the main cpu (blue box in picture below).

I found that most folks who bend Casiotones put together a box of banana jacks (one jack for each bend point) that can be connected by a lead wire with two banana plugs that are also connected to a potentiometer. Next step, though, is to identify all of the bend points and solder wire leads to each - I found 42 points, plus an upper-pitch point (the two red wires in the second photo below).


Wires are then threaded to box attached to side of Casiotone and soldered to the banana jacks. Solder solder solder:


Finished box with everything soldered in place, and two sets of lead wires. Bend points are linked to the grid of 42 plugs at the top, and the two connecting plugs to the 100k pot are at the bottom.


Here's a clip of the finished keyboard demonstrating the rhythm function using the "16 Beat 1" setting - I also made a temporary 100k pot connector out of an old tuna fish can so I could play around with a second set of lead wires:



Next up is a Yamaha PSS-270 keyboard. Stay tuned...