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circuit-bending

 

Bending the Omnichord OM-27

 

 

 

You got an Omnichord too? Great! And it´s got only this one, pretty cheasy sound, well...

there is a lot you can do to improve the sonic qualities of your instrument and explore lots of new sounds and possibilities.

 

bend your

Omnichord today!

turn your

OM-27 into a

shiny beast of

sound

For the first steps you only need a Phillips srewdriver to open it, two miniature srewdrivers to access points on the circuit boards, and a external battery. NEVER USE A POWERSUPPLY WHEN TOUCHING THE CIRCUIT BOARDS !

The OmniConcertino

explained

You can also use your fingers, to touch areas instead of individual points. Generally, points on the main-board, where the chords and strumbar sounds are generated, are fed into the drumsound generation part on the halfround control-board.

the functional areas

of the FrankenChord

 

Check out these pictures to get an idea where these points might be. Find your own hot spots!

the body-contact points

on the OM-27 control

circuit-board explained

 

THE SAFETY RULES

 

before you even think of opening any device:

Do NOT connect it to a powersupply, use internal or external batteries instead. This is substancial, don´t risk your life! If you want to connect to external gear use also a D.I.-box. Again, these are absolutely necessary safety rules.
When you connect points on the circuit-boards, especially with two hands, electricity will travel through your body (very little though). Think about that, it´s at your own risk.

the body-contact

points on the

OM-27 control

circuit-board

explained

 

 

Thanks to Rob Hordijk I now got the description of the main chip of the OM-27. It was only used in this model, later models, like the OM-36 and OM-84 have a different chord generator and control-chip (M50740-701SP and M5M82C54P-6). If you happen to have any information on these chips, please contact me.

description of the

OM-27´s chord generator

AY-5-1317A

 

There are two different keyboard matrix layouts provided. Both use all twelve keys of the chords. Why does the Omnichord only have 9 keys? Have the circuit designers messed up? Is it on purpose based on statistics that show that the missing keys almost never apear in popular music? Who knows...

 

I got the chip layout just recently, time will show what silly things can be done to the chord management.

two keyboard-matrix

layouts for the

OM-27´s main-chip

AY-5-1317A

 

 

to the Omnichord history page