The late 1970s and early 1980s are renowned for a lot of great things. The Commodore 64 personal computer. The Keytar. Midi. Unfortunately plastic isn’t one of those things, as any MCI console owner will know.
As the story goes, MCI approached Penny & Giles about VCA taper faders for the JH-50 automation system. P&G expressed no interest at all in making such an unusual taper so MCI outsourced the manufacture of custom 10K ohm VCA taper faders to Waters. The result is a large, smooth, easy to maintain long throw fader that adheres to the standard 100mm standard throw standards but has a huge 142mm mounting hole spacing compared to the P&G/Alps 120mm standard. The only drawback is the rubbish 1970s brittle plastic used at each end of the fader to essentially hold everything in place… and I mean everything. It holds the two rails for the wiper to slide along, secures the front and back covers of the fader together, and mounts the fader to the faceplate via two little metal embedded threads.
The all too common symptoms of the plastic components are splits and cracks along all mounting points. When I first received my MCI desk, about 40% of the faders had fallen down away from the faceplates resulting in the fader cap rubbing up and down along the faceplate. In most instances the little embedded thread had parted ways from the plastic end pieces. Due to the unusual size of the faders, there aren’t any straight forward replacement options. You can either machine some new end pieces, machine 142mm to 120mm brackets to mount new P&G or Alps faders, or buy some heavy duty plastic glue and get to work…
Cleaning the original faders isn’t a difficult task at all. There is a little leeway provide too, given that the faders themselves don’t pass any audio. You won’t suffer from any audible clicks and pops in the sound if they are dirty as the faders simply alter the control voltage sent to the VCAs (Voltage Controlled Amplifiers). You will be pretty shocked what you find inside 30 year old faders. I dug out about a full head of hair, plus some mouldy old corn chips.
Give the inside of the case a dusting with a clean, dry paint brush. Remove one of the plastic end pieces entirely and pull out the two rails and wiper. Clean the resistive tracks with a cotton tip and some distilled water. Clean the rails and wiper with some metholated spirits. Reassemble. Grease the rails with a small amount high viscous grease and you are away! The bumpy, gritty feeling faders will be transformed to smooth gliding faders with a touch of resistance in their travel. If you prefer the feel to be smooth and light, you can substitute grease with a dab or two of machine oil. Just keep it off the resistive track!