Fader Maintenance Procedures

 

The following information applies to both manual and motorized faders. 

If you have manual faders, skip over the sentences dealing with the motorizing components.

 

As with most electromechanical assemblies, the motorized faders used in the Flying Faders systems require periodic maintenance.  The following documents outline the recommended maintenance procedures for the faders.

 

In general, these procedures should be executed on a regular basis before the drag of the fader rises to objectionable levels.  As with your automobile, failure to clean and lubricate on a regular basis will accelerate the wear of the components, leading to premature failure and expensive replacements.  Under typical situations, the rods of the faders should be lubricated about every 6 months, and the tracks be cleaned and lubricate with PTFE spray annually.  Extreme environmental conditions such as heavy cigarette smoke or other contaminants may require even more frequent cleaning.

 

You motorized faders are an asset that will serve you for a very long time if treated properly.  On the other hand, neglect or abuse of the faders can become a very expensive problem to correct.

 

Notes regarding severe wear

 

All motorized faders, regardless of brand or application, are subject to more wear than manual faders.  If the faders do not receive adequate preventive maintenance, the conductive plastic tracks and the brush contact fingers will experience accelerated wear.

 

Normal wear will produce a change in texture of the contact area along the conductive plastic track.  The contact point of the brush contact fingers will also show a small flat spot.  These indications are normal and will not prevent proper operation after cleaning and relubrication.

 

If not maintained properly, heavily worn faders will have large flat spots worn onto the brush contact fingers and deep gouges worn into the conductive plastic tracks.  Restoration of badly worn faders is not always successful.  The brush fingers may be worn enough to begin digging into the track, producing rapid subsequent degradation of the track and brush.

 

In extreme cases, blue material could be visible within the track region, or the contact finger could be worn completely though so that the sliding contact becomes a point.  In either of these extreme cases the tack and slider assembly would require replacement.

 

Versions of P&G faders

 

Over the years, P&G has incorporated various improvements in their faders.  The most significant change happened about January 1994 when P&G began using a special treatment that helps trap the silicone oil on the rod.  Since the oil is a very low viscosity type that easily creeps onto any adjacent surface, the oil would eventually migrate away from the rod via the end blocks and slider assembly.  The treatment establishes a surface tension barrier to the oil that works similar to the little balls of rain produced by applying RainX on a car’s windshield.  The oil is repelled by the treated surface, thus cutting off the migration paths for the oil.  MANCO provides this oil repellent treatment on faders that we rebuild.  New end blocks and sliders are factory-treated with the repellent.

 

A second, smaller change with respect to the oil deals with the rubber bumper washers at the ends of the rod.  The original salmon-colored silicone rubber washers could absorb the silicone oil, and in some cases the washers would stick to the sides of the slider assembly due to a suction effect.  P&G replaced the silicone rubber washers with firmer black Nitrile rubber washers that do not act like oil sponges.  The part number for the new washers is P62919.

 

Our experience is that updating older faders with the oil-entrapment features extends the cleaning/lubrication interval by a factor of 2 or 3.  This treatment also allowed P&G and Martinsound to go back to using the original white PTFE (Teflon) bushings that provide a better feel.

 

Flying Faders drive components

 

The motor, pulleys and drive cord have demonstrated excellent durability.  The motor is a premium motor that features a ball bearing for long life.  No motor maintenance is required.

 

The ball bearing pulleys may require cleaning and relubrication, but usually only under severe conditions.  Remove the old lubricant by washing the bearing in an ultrasonic bath with an appropriate solvent.  Relubricate with a light bearing oil or grease.  (The nylon shell of the pulley can easily be pressed off the bearing outer race if the cleaning or relubricating process might damage the nylon.)

 

Two problems have been experienced with some batches of pulleys.  The nylon ring may not be pressed onto the exact center of the bearing, causing unequal overhang on the front and rear of the pulley.  If the ring overhangs the rear of the pulley too much, the face of the ring may rub against the shell of the fader.  Flipping the pulley over or re-pressing the ring to center it on the pulley will solve this problem.

 

The second problem stems from the process of making and installing the nylon rings.  Small hair-like strands of nylon may stick out from the outer rim or the center where the pulley is pressed in.  These strands may strike the drive cord or the shell, producing a ticking sound as the fader is moved slowly.  Examine the pulleys with a magnifying viewer and remove any strands with an Xacto knife.

 

The drive cord must be free of lubricants or dirt that could cause slippage on the motor capstan.  The cord used in the Flying Faders fader was chosen for high dimensional stability over time.  Kinks or nicks, however, can cause cord breakage.  The usual source of nicks is re-tensioning the string under the locking screw.  Normal maintenance does not require release of the locking screw!  The string can be slipped off and onto the pulleys by hand without releasing the tension.

 

MANCO stocks the special co-filament drive cord for Flying Faders motorized faders and both the black and white woven drive cords for P&G motorized faders.

 

Lubrication

 

Since the fader slider is a moving instrument, periodic lubrication is required to maintain smooth performance.  It is very important, however, to only use recommended lubricants.  If conventional petroleum-based lubricants are used, a residual buildup may form that could negatively affect performance.  These lubricants may also have solvent components that will damage the conductive plastic tracks.

 

Use only the following lubricants:

1.      Rod and bushing lubricant – Penny & Giles P/N D23402 Dow Corning silicone oil @$30/bottle (enough for lubing over 100 faders)

MANCO

1694 Calle Zocalo

Thousand Oaks, CA 91360

www.manquen.net

(805) 529-2496

 

2.  Conductive-plastic element lubricant - PTFE dry film spray such as Electrolube DFL 200 supplied by:

Echelon Inc.

20681 Truss Court

Diamond Bar CA. 91789

http://www.echeloninc.com/

(909) 595-3492  for $12/can (4/6/06 price).

 

Fader disassembly

 

Caution!  Prepare a work surface that will catch any parts that might fall out of the fader during disassembly.  DO NOT work over the open surface of a recording console where parts can fall through slots, causing internal short circuits or loss of the fallen part.

 

1. Before disassembling the fader, test for noisy pulleys.  Briskly slide the slider from one end to the other, noting any excess noise from either pulley.  Mark any noisy pulleys for servicing later.
2. Hold the fader on its side with the motor and string on the top side and the large pulley closest to you.  (Use the opposite orientation if you are left handed.)  Pull the slider all the way to the end stop near the large pulley.  Note that the string runs from each pulley to the underside of the motor capstan, and that the string from the large pulley winds onto the lower part of the capstan, nearest the motor mounting plate.  Disengage the string from the small pulley by rolling the string out of the pulley groove as you move the string around the small pulley.  The slider will move up the fader as you move the string.  Once the string is free of the small pulley, unwind the string from the motor capstan and the large pulley.
3. Hold the fader vertical with the large pulley upward.  Remove both screws from the end block at the large-pulley end of the fader and remove the end block.  (A #1 sized Posidrive screwdriver works best.)  The metal ‘washer’, the 5-sided piece of shiny metal under the head of the screw at the top of the fader, serves as a retainer for the square nut used for mounting the fader to the top panel.   Remove the nut from the end cap, then remove the end cap, and finally remove rubber washer on the end of the guide rod.
4. Pull the curved ‘shed’ out of the lower end cap, slide it through the slider and put the shed aside.
5. Wrap the loose drive string around you fingers to avoid snagging it and carefully slide the slider assembly out of the fader body.  Removing the slider from the large-pulley end allows the contact wipers on the slider to compress during the extraction.  We will use the other end of the fader for re-inserting the slider for the same reason.
6. Remove only the lower screw from the small-pulley end block and remove the end block with the guide rod still attached.  Leaving the guide rod attached avoids fumbling with the second square nut, and it provides a convenient handle for cleaning the guide rod.
7. Push the blue substrates containing the conductive tracks out of the metal casing.  DO NOT PULL on the wires to remove the substrates!  Some faders will not have enough slack wire on the motor to permit the substrate to be removed.  In this case, use a sharp tool to depress the locking tabs in the Molex connector for the two motor wires, and then remove the substrate.  Bend the locking tabs outward again so that the contacts will latch properly when they are re-inserted later.
8. The tracks are now ready for cleaning.  I have always used isopropyl alcohol for cleaning the tracks, rod and bushings, but P & G recommends: 

Remove the track, clean off any debris using a lint-free cloth and rub firmly down the length of the track until all traces are gone.  If the deposits on the track are difficult to remove, then the track should be washed in warm water.  If required, brush gently using a soft brush.  The track should then be thoroughly dried using a cloth and a hot air dryer.  When the track is thoroughly dried, it should be rubbed with the lint-free cloth to remove any marks. 

Agitate the spray can of PTFE dry film lubricant by shaking the can vigorously.  Hold the can such that the nozzle is 6” to 8” away from the track and spray the lubricant over the track surface in one slow (2-3 seconds) sweep.  Allow the solvent to evaporate.  The track will appear white after drying.  Polish the lubricant into the track with lint-free cloth until the surface of the track is shiny.  Inspect to ensure that all areas have been polished.  (Areas having a matte appearance require further polishing.) 

If required, place a new piece of adhesive foam strip on the rear of the track.  This is only necessary if a foam strip was originally fitted on the rear of the track and was damaged during removal or cleaning.

9. Wash the guide rod with a lint-free cloth wetted with isopropyl alcohol.  Prime the surface of the rod by wiping the rod with a lint-free cloth wetted with silicone oil.
10. Clean the tips of the slider brushes by dipping them in isopropyl alcohol and gently brushing them with a soft brush such as a toothbrush.  Only stroke along the length of the wires.  After the brush wires are clean, use a magnifying viewer to examine the wear pattern on the wires.  The worn area should not be longer than .00x” or .yy mm.  If the brush wear is excessive, replace the sliders as soon as possible to avoid permanent damage to the resistive tracks.
11. Clean the bottom slot (guide channel) of the fader shell with a Q-Tip moistened with isopropyl alcohol.
12. Inspect the motor and capstan.  Check the shaft area between the bottom of the capstan and the top of the motor.  Some motors were assembled with too much Loctite, leaving a residue of blue or green fluid at the bottom of the capstan.  If any fluid is present, thoroughly clean the area with a cotton swab dampened with alcohol.  Avoid excessive alcohol that might was lubricant out of the ball bearing at the top of the motor.
13. Any pulleys found to be noisy should now be serviced.  Some pulleys utilize ball bearings that have removable shields, while others have shields that are permanently staked into place.  Either type can be washed in solvent, preferably in an ultrasonic bath, and then re-lubricated with a light bearing oil.  Stubborn bearing with removable shields can be opened up for a more thorough cleaning.  Use a very sharp tool such as a sewing needle to lift one end of the circular retaining clip.  Once the clip is removed, insert the needle between the shield and the center race to gently lift the shield off.  Wash out any dried out grease, apply light bearing oil, and reassemble the shields.
14. Re-install the blue substrates in the fader shell.  The substrate with the 8-pin connector fits against the pulleys with the wide conductive track at the bottom and the wires exiting near the large pulley.  The other substrate is installed from the small-pulley end with the 5-pin connector across from the small pulley.
15. Install the slider assembly from the small-pulley end with the drive string attachment toward the motor and pulleys.
16. Verify that the rubber bumper washer is still on the rod/end cap assembly.  Insert the guide rod through the slider bushings from the large-pulley end.  Fasten the end cap to the shell, taking care not to pinch the wires.  Place the other rubber bumper washer on the guide rod, snap the other end cap into place and install the lower screw through the ground wire lug.  Temporarily leave the upper screw out.
17. Move the slider to the middle of the fader.  Apply one small drop of silicone oil on the guide rod next to the slider on each side.  Slowly slide the slider back and forth to evenly distribute the oil along the rod.  DO NOT OVER-OIL!!  Too much oil will cause intermittent contact at the sliders, causing servo overshoot and audio noise.  You should never see any evidence of oil on the resistive tracks!
18. After determining that the slider moves smoothly, slide the shed through the crescent slot in the open end cap.  Insert the square mounting nut into the end cap, cover it with the metal ‘washer’ and fasten with a screw.
19. Move the slider to the large-pulley end.  Wrap the drive string around the large pulley and firmly pull the string toward the gap between the fader shell and the capstan.  Wrap the string around the capstan 3 times in the counterclockwise direction, maintaining tension.  While holding the string taut around the capstan, use your other hand to pull the other side of the cord from the slider around the top of the small pulley.  Use your thumb to hold the cord in the pulley groove while you slowly turn the small pulley counterclockwise.  The cord with thread around the pulley and drop into the groove after you get past the far side of the pulley.  Move the slider from end to end a few times until the wraps around the capstan equalize.
20. Re-insert the black wire into position #5 and the red wire into position #6 of the Molex connector.  Check that the latch tabs properly lock.

 

Fader Testing

 

Several software tools are available to assist with exercising and evaluating faders.  Consult the Diagnostics section of the Flying Faders manual for more details and complete syntax:

 

TEST MOvefaders +/-xxx  [range of faders to test] initiates a move of faders to the dB value of plus or minus xx.x dB.

 

TEST Faders [range of faders to test] runs a sequence starting with random moves of all faders, followed by a ‘teeter totter’ anchored at the fader position NUMFAD/2, followed by a quick flip of each fader in sequence over the full range of faders twice, then random mix-like moves with the lights sequencing up and down along with each fader.

 

TEST SPeed GRaph [range of faders to test] executes full speed flips of the fader in each direction and graphs the result, showing the slopes and any overshoot.  The display also shows the overshoot, undershoot, and times required for the fader to be close to the final value and very close to the final value in each direction.  Excessive overshoot can be caused by a loose drive cord or excessive lubrication causing hydroplaning of the slider fingers at high speed.  A range of faders can also be graphed one at a time.

 

TEST SLIP is used to test for string slippage on the motor capstan.  The test begins with Fader #1 moving slowly from bottom to top of the fader to generate a software table of dB to position conversions.  (The computer normally doesn’t know the physical position of the fader slider since the hardware ROMs interpret all dB values sent to the hardware to determine the appropriate position of the fader, depending upon fader taper and panel markings.)

Next, all faders are moved to the center of the fader stroke.  This test reverses the normal logic of the touch sense circuits, which normally turn off the motor whenever a fader is touched.  For this test, touching a fader knob activates that channel’s servo to hold the fader at the middle position.  Pushing the fader knob up and down provides a test for any loose drive cords.  If you can hear a motor begin to spin at high speed when you try to force the fader in one direction or the other, the cord is slipping.  Test each fader.

 

TEST Friction 1 [range of faders to test] is used to evaluate the ‘slipperiness’ of each fader in each direction at 20 points across the stroke of the fader.  The test may begin with the generation of a software table as described above if no prior test has already built the table.  If the table already exists from a prior test, the fader will be positioned at the bottom.  A short burst of power is applied to the motor and the amount of coasting is measured.  The farther the fader moves, the better the ‘slipperiness’, indicating good lubrication and low friction.  The test displays a table of the 20 values for the ‘up’ (/) direction and the 20 ‘down’ (\\) values.  Larger values are better.  The values for the downward stroke are typically larger than the upward stroke because of the direction and geometry of the slider contact fingers.  The values near the end are typically smaller due to the patented cord-tightening feature of the Flying Faders design.

 

Since there are several variations of fader construction, there are no hard and fast performance limits for the above tests.  The data presented by these tests is best used for comparisons with a set of reference data taken when the faders have been freshly serviced.  This will show any degradation before it becomes a serious problem.

 

A handy tool for testing faders is shown below.  This dual-mode power supply can move the fader slowly along the track to check for smoothness, or it can be used to slam the slider against the end stop to check for drive cord slippage.  Set R2 to provide a “creep” output voltage that moves the slider across the stroke of the fader in about 2-4 seconds.  This slow motion will stall if there are any high-friction points along the stroke.

 

The “slam” test applies full voltage to the motor.  If the string is properly tensioned, the motor should stall at the ends without any slippage.  The Flying Faders servo drive circuits provide a maximum drive of about 10 volts to the motor terminals.

 

 

 

Fader Tester Schematic