MCV2 Description and Application Notes:

The controller is designed to provide 2 speed plus stop capability for 22H and 47 single motor/single speed leslies. In addition, it provides compatible replacement circuitry for the speed change logic in the amplifier. 

Compared to the other available slow motor emulators, this controller has more variable speeds in slow mode (40+ vs 4), and is fully compatible with Bob Schleicher’s 3 mode switching scheme. The technology used will make the motors run cooler and quieter. 

The speed control of the motors is based on the latest technology in induction motor control employing a PWM based Variable Voltage/Variable Frequency (Ve/Vf) scheme controlled by an onboard PIC Microcontroller. The 25Khz pulses from the drivers are width modulated to emulate a pure sine wave at the desired motor frequency and voltage. The firmware models the ballistics of the 2 speed Leslies (122/147) as closely as possible, and also includes a 2 mode stop feature that allows a properly equipped switching kit to emulate either a coast to stop or hard brake via a jumper setting on the controller.

By using Ve/Vf waveforms the motors are able to more closely match the speeds found in the 2 speed leslies when compared to full wave/full voltage (pulsing) used in older less sophisticated controllers. Another advantage is that this technology puts much less strain on the motors resulting in much less heat dissipated while running in either slow or fast. The controller will fit inside the chassis of most Leslie amps (we haven't found one yet we couldn't fit it in). The leslie interface is built in, so you can pitch the old relay/tube stuff. And you can change between 47 (Universal) and 22H (Hammond console balanced line) operation with a component swap. For the "upside down" mounting in amps other than the 22 or 47, a #6 standoff is supplied for mounting over the choke. The slow speed pot and the brake/coast jumper can be mounted on the reverse side of the card for this type of installation. More information as to mounting will be supplied as the dealers figure it all out. By the way, thanks guys!

Support:

All of the parameters are based in software routines – changes to the actual behavior of the card can be made by replacing the socketed cpu with an upgraded part. A diagnostic/exercise chip is also available to authorized dealers for automated system checkout and troubleshooting, along with full documentation, a spares kit, theory of operation, tips and schematics. Tech support is also available online at support@rtclogic.com

As with anything trying to do the impossible, there are a few caveats and requirements in order for the board to emulate a 2-speed cabinet successfully. Motors should be cleaned and properly lubricated, belts must be tensioned correctly, and all other drive components should be checked for wear and excess friction. The upper and lower motors perform best when their DC resistance (cold) is within .5 ohms, and the closer the better. The slow speed adjustment should be performed after the chassis has been allowed to come up to operating temperature, typically 15 minutes.