EMU Emulator III - EIII - E3 - Power Supply - Direct Replacement/Upgrade - Plug n Play

This is a direct replacement for the Emulator III synthesizer.  The footprint, mounting holes, and connectors are identical to the original which allows for easy, trouble-free replacement.  The input and output connectors are labelled with their respective names and/or voltages, which allows for quick identification and troubleshooting in the future.  The only 'modification' required is to cut and remove the voltage selector switch wires, or coil them up and zip-tie them out of the way.

The original E-mu service manual has clear instructions for opening the EIII keyboard (and rack version) including removal of the power supply.


The service manual can be downloaded here: https://archive.org/details/e-mu_Emulator_III_Service_Manual
See pages 35 & 36 to open the keyboard, and page 38 for removing the power supply.

This design is intended to be very efficient, while providing ample output current.  I decided to utilize separate power supply modules for this design that are fully encapsulated.  This greatly improves safety as there are no exposed hazardous voltages.  The use of these modules and surface mount components reduces construction time and cost.  The 5V digital supply is derived from a 15V supply by a buck convertor.  This arrangement allowed the PCB footprint to be identical to the original while providing an extremely stable output voltage for the digital circuitry. (it only varies ~5mV between no load and 15A).

I have provided additional solder through holes for the 5V supply and the Stereo Relay Modification.  You will find some EIIIs with the 5V wires soldered directly to the Molex pins.  This is acceptable and will provide a reasonably robust connection, but I decided that proper through holes would be most beneficial for anyone looking to reduce the resistive losses associated with using the original cable and Molex connector.  

The Stereo Relay Modification is present for those who wish to easily bypass the output relays.  There is a ribbon cable that is known to fail, which mutes the output relays.  You can repair the ribbon cable, but some folks prefer to make the relays always on.  

Power Supply Specifications:

Input: 100-240VAC

Output:

  +5V @ 15A (20A max peak)

+12V @ 5A

+15V @ 1.4A

 -15V @ 1.4A

Please feel free to reach out to me with any questions or concerns.  If you are in search of a power supply replacement for a different piece of musical equipment, please contact me.

***Always be extra careful when working around AC mains voltages!  Do not attempt replacement unless you feel comfortable with the process and take full responsibility for your actions.  You alone are liable for any harm or damage incurred during the installation and use of this product, and by purchasing this product, you accept these terms.***