Static-Proofing Your RealFlight™ Controller

A while back there was a thread running around one of the forums regarding someone who had blown out the gameport on his or her computer because of static discharge through the controller box.  It was interesting to see how quickly the thread progressed into a blamestorming session, trying to determine who was at fault (the sound card manufacturer or the software/hardware manufacturer).

Less than a week later, a tingle felt through the throttle hold switch on my controller while simulating resulted in a dead input on the game port of my $200 sound card.  I knew immediately what had happened.

The controller has four pots internally and three external switches, all of which are isolated from metal on the controller case.  The problem is that the switches are not isolated well enough.  Even though the contacts on the switches are insulated from the metal toggles,  it doesn't take much of a static discharge to the toggle to jump internally to one of the contacts, and straight down the wires and into the vulnerable inputs of the game port on your sound card.

Products marketed in or to  European Union countries must undergo vulnerability tests demonstrating the ability to survive, and in some cases operate during electrostatic discharge (ESD).  Unfortunately, there was no CE mark to be seen on the sound card or the controller, which would have indicated that some degree of compliance to the European standards had been demonstrated.  I was screwed.

Most game pads have buttons, pads, and joysticks that are entirely plastic.  It would take an extremely high voltage to jump from your hand to the internal circuit board.  Unfortunately, the RealFlight controller needs to have its metal switches grounded to the metal case of the computer through the cable.

The 15 pin DSUB connector on the end of the controller cable is metal and makes contact with the connector on the computer, but there are no wires or shield in the cable connected to the shell of the connector. But the good news is that there is a shield in the cable that provides the extra conductor that is needed--you just need to get to it.

How to add the ground:

1) Open the RealFlight controller case.  Where the cable enters the top inside, some trace of a foil shield and a bare wire wrapping around the colored wires should be evident.  If not, carefully trim back a little of the plastic sheath to expose a wire and/or foil.   Remove any excess foil.

2) Remove the decorative nut rings from the three toggle switches and pop the switches out of their holes.  Prepare three lengths of fine stranded plastic insulated wire (about 8-10" long) by stripping about 1/2" off one end of each.

3) Stick the bare end of one of the wires into a switch hole and insert the respective switch so that the threaded barrel of the switch makes a reliable contact with the switch fully inserted.  File a little notch in the side of the hole if necessary to accommodate the wire diameter.  Trim the protruding wire to about 1/16", and reinstall the nut so that the wire is flattened under the nut.  Repeat for the other two switches.

The wires cannot be soldered to the switches, so they need to make mechanical contact.  File a notch or enlarge the hole as needed to fit the wire in the hole along with the switch barrel.

 

4)  Trim and solder the three wires together and connect to the bare wire coming out of the cable (that you exposed earlier).  You cannot solder to the foil.

I used a resistor to tie the three switch wires to the cable ground to provide a current limiting "soft" ground.  This is not necessary, but if you want you can use a 10k to 100k ohm resistor.  It will make discharges less noticeable.

 

5)  Reassemble the case.

6)  At the connector end of the cable, make a lengthwise cut  1/2" long in the plastic sheath of the cable about 1"-2" from the point where the cable enters the connector.  Do not cut too deep.

7)  Use small diagonal cutters or a knife (carefully) to cut around the sheath, removing the entire 1/2" long section of sheath.  You should see the foil  wrap and the bare ground wire.

8)  Solder a short length of stranded wire to the bare ground wire.

9)  Trim the open end of the wire to length so that it can reach the metal shell of the DSUB connector without strain, and solder it to the shell where it won't interfere with mating of the connectors.

Be careful that you don't cut any of the colored wire when removing the cable sheath.

 

 

10)  Wrap the stripped area of the cable with enough turns of tape to make it as stiff or stiffer than the unstripped cable around it.

Tape keeps the cable from flexing at the weak point.  Heat shrink would be ideal, but there's no way to get it on the cable.

 

11)  You're done.  Feel free to run to your computer in your sock feet and give the controller switches a good knuckle snap.  The discharge will be routed safely to the computer case.

 If you use a gameport extension cable, DON'T.  Chances are that you will lose the ground connection that you just installed, since most extension cables that I have seen do not have ground continuity.

Also make sure that the metal panel on your soundcard is making contact with the back of you computer case, and that the screw that holds the board in place is tight.  Without contact with the case there is no guarantee that the DSUB gameport connector is grounded.

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