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Old 10-31-2018, 05:33 PM
ibanman555 ibanman555 is offline
Join Date: Apr 2005
Posts: 71
Default The Definitive Digidesign Pro Control Repair Thread

In the interest of Neyrinck's current resurrection of the Pro Control and Control 24 to the most current versions of Pro Tools, I thought I would place a specific thread focused on the repair and up-keep of our Legacy controllers! As we can see we are a small group, and most likely expanding as word gets out that these so called 'paperweights' are no longer. For a few hundred a perfectly functional main unit can still be purchased... This is because those selling don't know they can be used once again!

**As always, I am willing to help answer any questions or assist in repairs or rebuilds! PM me!**

I am bringing some life back to the Pro Control, and I have an issue with a few Digifaders. I was able to restore what I have, full action after recalibration and appear to be fully functional again.

The Digidesign DigiFaders can have a number of problems, first being what I feel is most common, the 'dead fader' problem. Upon startup, all faders will attempt a full sweep from 100% to 0%. If they hang up any significant amount, the motor will shut off, and will not attempt to function again until restart or a successful fader recalibration occurs.

I have found a number of causes for a 'dead fader' and this is what I feel is the best solution. Fader caps should be pulled or reinstalled when the fader is at its most upper or lower position. There are 2 metal bars that the fader rides on and pushing or pulling on the fader can cause these metal bars to bend. There is more support at either end.

The DigiFader runs dry, and there is no lubricant on the metal bars. I can see how many years of use can wear out the plastic runner that rides on these metal bars. Originally, the inside of the holes that these bars ride through had ribs, keeping the friction to a minimum. I can see that these ribs have worn, and that causes more surface area and friction, ultimately causing the fader to cease movement fully from top to bottom.

I have brought these faders back by reaming out these holes in the plastic runner, and using CRC 2-26 lubricant all over the parts that touch and ride against each other. Recalibrate and all faders move full throw. Reaming the plastic runner may cause a bit of lateral play in the fader but they are functional once again!

I have faders that do not respond to touch. Under Utility, I open the touch test option and all but 2 faders show approximately 175 kHz. When touched, a small 'T' displays and the value drops to 70khz.

2 faders rest at 16khz and when touched do not change in value nor display a 'T'. I did some testing on the faulty faders and there is resistance between the fader and ground, about 7 ohms. However there is no resistance showing on the faders that work.

I've swapped faders to see if it was a ribbon cable or something with the main board, but they follow, which tells me it's the fader that is the issue.

UPDATE: 10/25/2018
The failed touch sense on the fader is caused by a faulty 0805 capacitor on the fader circuit board itself, location C5. The fader is acting as though it is grounded, without touching... This causes the wrong displayed frequency, and will not respond to touch. I've pulled this capacitor and replaced it with a component of the wrong capacitance, but it works in the mean time for testing purposes. The wrong capacitance won't allow for me to touch the fader with a finger, but if I place my other hand on a metal surface of the Pro Control, it will properly complete a touch circuit. From my testing, the approximate value capacitor for C5 is a multilayer ceramic capacitor 0805 320pF

UPDATE: 10/20/2018

I had the telltale signs of a 20 year old Pro Control, so my first task was a PSU rebuild, regardless if it needed it or not. I didn't even power it on before I did this. I replaced 12 capacitors on the main PSU (yes, there are 2 PSUs). This was done properly, solder was extracted from the board completely using a vacuum and resoldered. The same was done with both Molex connectors on the PSU. The original factory soldering method and material was low-temp and quick... Very poor Chinese work. Completely replacing the solder gives much better electrical continuity and will help prevent any future problems. Here is a list of current capacitors for this project (actual PSU Board locations in Bold) :

1x PC C7 / 381LQ331M400K032 Cornell Dubilier - CDE 400Volts 330uF 30X35 / Aluminium Electrolytic Capacitors - Snap In

1x PC C9 / UPJ1V560MED1TD Nichicon 56uF 35 Volts 20% / Aluminium Electrolytic Capacitors - Radial Leaded

3x PS C10, C28, C26 / UPM1E121MED Nichicon 25volts 120uF / Aluminium Electrolytic Capacitors - Radial Leaded

2x PC C25, C29 / UHE1V221MPD6 Nichicon 35volts 220uF / Aluminium Electrolytic Capacitors - Radial Leaded

3x PC C20, C18, C19 / UVY1C222MPD Nichicon 16volts 2200uF / Aluminium Electrolytic Capacitors - Radial Leaded

2x PC C17A, C17 / UPW1V222MHD Nichicon 35volts 2200uF / Aluminium Electrolytic Capacitors - Radial Leaded

Since the PSU historically causes these problems, it doesn't hurt to give a refresh. I am not sure of the 2nd PSU's purpose yet but since I got up and running with zero problems, I've chosen to leave it alone at this point.

Before a complete install the Pro Control was completely disassembled, main boards left inside the metal case however. I took the fader panel and placed it upside down, and using supports around the perimeter so that the buttons would not be pushed on. Many screws allow the main circuit boards to be removed from the panels, exposing the button caps. I would recommend documenting with photos and keeping track of different length screws. Circuit boards carefully set aside, the plastic button caps and panel dipped into a hot bath of dish detergent (non bleach) and scrubbed into perfect cleanliness!! The same was done with the main panel section, but take care here as there are many more circuit boards that need to fit snug.

The main boards inside the base of the Pro Control were treated with compressed air from my filtered line, no more than 60 psi to remove the dust. That was the extent of cleaning there.

I do have a segment out on the Numerical Display of the meterbridge. This replacement will also require proper desoldering, as they are directly attached to the meterbridge board. Once i have it removed I will confirm the dimensions and suitable replacements.

Last edited by ibanman555; 10-31-2018 at 11:15 PM.
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