NSI Multiplex Daisy-Chaining

I have a nifty box that converts DMX-512 to NSI Multiplex. It comes in very handy when I need to control my old portable dimmer packs with a newer light board that only has a DMX output. The one down side is that it only has a single XLR jack for the Multiplex bus. This means that electrically it must be installed at the end of the chain and if it can't be physically located at the end I have to use a ton of extra microphone cable doubling back. The good news is that it is very easy to add a second XLR jack.

Most devices NSI makes have two XLR jacks- one male and one female- so that you can easily daisy-chain them together with standard microphone cable. The two jacks are simply wired together; pin 1 to pin 1, 2 to 2 and 3 to 3. There is no active repeating of the signal between the connectors, so adding a second jack to a device that doesn't already have one is as simple as wiring one in.

The converter I'm using is a DMX-lator I by DMX-tools. I've had it for several years and it has worked flawlessly. John, the guy who designed it, is very friendly and helpful as well.

What You Need

• Male Panel-Mount XLR Jack
• Screws for Mounting Jack
• Some Wire (3 different colors recommended)
• Phillips Screwdriver
• Soldering Iron
• Solder
• Drill
• Drill Bits
• Sharpie

Install the Jack
The following instructions are specific to the DMX-lator I, but the basic idea would apply to any device with only one Multiplex connector.

Remove the four screws that hold the cover on the case.

Remove the cover.

This is the tricky bit; here's a quote from the manufacturer's website describing how to get the PCB out:

"The board is held in by the XLR connectors. First remove the flat-head screws that hold the connector to the cabinet. Then, if you look into the end of the XLR connectors, you'll see an extra hole that doesn't correspond to any of the pins of the mating connector. At the bottom of the hole is a quarter-turn fastener. Use a jeweler's screwdriver to turn it counter-clockwise. This allows you to remove the collar of the connector. After you've removed the collar from all three connectors, the board comes out easily."

Drill a hole in the side of the case for mounting the new connector. Make sure to choose a location where it won't make contact with anything protruding from the PCB.

Drill screw holes for your connector.

Connect a wire to each pin the XLR jack. Label the other ends with pin numbers or write down which color goes to which pin.

Feed the wires through the hole and screw the jack into place.

Now would be a good time to figure out which pin numbers on the Multiplex jack go to which solder pads on the PCB. Label them with a Sharpie. I labeled mine with Photoshop. You can cheat off of my work if you want to.

Replace the PCB, making sure that the new wires are routed beside it and to the solder side of the board.

Re-fasten the XLR connectors and screw them back into the case.

Solder the three wires to their respective pads on the PCB. Remember, 1 goes to 1, 2 goes to 2 and 3 goes to 3. Make sure to trim off any extra length.




Screw the lid back on.

That's it! Now you can daisy-chain your Multiplex device and use all that extra microphone cable you saved for something useful like microphones.

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