No, this isn’t going to include a video of Tom Guilmette flying in slow motion. I’m just hijacking his title. This post is about going inside an audio console to repair some of the faders that stopped working properly.
In my real life as a Broadcast Engineer things can come up in the course of a day that will test your mettle. Today’s trial of character came in the form of finding out a few hours in to my shift that I’d be staying a few hours late to work on our digital audio mixing console. I got a report/complaint from the operator that some of the faders had begun ‘sticking’. Sticking is one way to put it. Another way to put it would be ‘fighting’. Or sometimes they go rogue and become ‘phantom’ faders!

Here’s and example of a ‘phantom’ fader, one which has a mind of its own.

If you’ve never worked with a digital mixing board you might think that my faders were sticky and not sliding well because someone poured soda and quickrete in there. If you have used touch sensitive mixing controls you probably know what I mean by fighting and sticking. I’m going to describe extremely briefly and broadly (at the risk of being inaccurate in places) what digital mixing consoles are for any one who doesn’t know and since I’ve not written about nor read about mixing consoles on this site, I have no idea who I’m writing to! If you’re well versed, feel free to skip the next paragraph, or feel free to read it and rip me apart over some trivial detail.

Overview of a Digital Audio Console

A digital audio mixer is pretty much what it sounds like. It’s a device that mixes digital audio signals together. It converts any analogue inputs to digital audio and once that has occurred it can mix and usually add effects and other dynamics like compression. Similarly, it converts it’s mixed digital audio back to analogue before coming out of the board for listening via headphones, etc…(in honor of the many great sound boards and products made by Brits I’m using their spelling of analogue). The big ‘wow’ feature of digital boards has to be motorized faders. This allows, amongst many other things, the board to use pages or layers so that it may have control over more inputs using less dedicated faders. By comparison, an standard analogue mixing board like a Mackie 1604 has a dedicated channel strip and fader for each of its 16 inputs. A digital board with 16 faders might allow you to have 32 inputs across two pages. It’s sort of the way a control key or a function key makes just about every key on a computer keyboard have a different function. While mixing you can push a button and all the channels will switch from page 1 (inputs 1 through 16 in our example) to page 2 (inputs 17-32). And you can go back and forth as needed. There are a ton of other advantages of digital audio boards but that’s a whole other topic.

Our board, like many other digital consoles, employs touch-aware motorized faders. Touch-aware means that, like an iPhone touch screen, it doesn’t do anything if you touch it with your fingernail. It uses the capacitance of your fingers to function. I guess this is to prevent putting a stack of tapes on the board and accidentally moving a fader up or something. Honestly, I can not think of a compelling reason for this ‘feature’. What this creates for me is a chance to get real good at removing fader modules. You see, there’s a little tiny motor and a belt that moves the fader around. And there’s also some sort of logic that tells the fader when to move and when not to move. Once that fader starts to get a mind of its own, forget about it. Before you know it, your faders will defy you. Sure, you can pull it down but it wants to be up-and has the ability to go back where it wants to be!
This is why when I hear that a few faders start acting up it can ruin my zen. One fader can be worked around for a short while. A few bad faders starts to get dicey. To get in there and do the work takes some time but it’s the what-if-I-put-it-back-together-and-it-doesn’t-work-at-all factor that you really have to allot time for. This all adds up to getting the tools ready for surgery after the last show is done for the evening. It’s time for some extra-innings!

The process of removing a bad fader isn’t all that daunting usually, though I wouldn’t recommend it to anyone. On this board you have to first remove the arm rest at the front. After that you can unscrew any of the fader banks which contain a pack of 8 faders.

A bank of faders being removed revealing the electronics inside

After that you can remove from the pack the offending slider by loosening two screws and it’s metallic cap. There are also two connectors that allow the motor to operate. One supplies power and the other relays the user input to the board’s brain.

A single fader after being removed

Here you can see the belt which the motor spins to move the fader. Looks and works like a mini Shuttle Pod.

Reverse the steps to reassemble. Next, Re-energize the board and cross your fingers. With any luck the board will work like new and you’ll be on your way home soon!