ESU SwitchPilot Servo problems and the SPROG 3 solution

ESU SwitchPilot Servo Version 2

I had a problem when we exhibited Die Keinnamebahn at the Rainford show in October. The ESU SwitchPilot Servo (Version 1) I was using to operate the remote uncouplers decided to overheat and fail after only 10 minutes of the show starting! This was despite it working successfully for over a week at home!

I determined that the unit was keeping all 4 servos powered up even when they had completed their operations. This overheated the the ESU unit in the cramped, unventilated, space under the baseboard. The SwitchPilot Servo Version 1 cannot be set to stop this occuring. On the other hand the SwitchPilot Servo Version 2 can be set so that the servos are only powered whilst moving and the servo power feed times out after a few seconds.

This function is set by setting CV50 to 4.

I tried to do this using my Digitrax DSC51 Zephyr Plus DCC control station, on both the programming track circuit as well as the running track circuit, but it was unable to read or write to the ESU unit. After delving into the ESU instruction manual, in small print, it states that Digitrax units do not have a high enough programming current to work with ESU units, even though they will happily control ESU units.

SPROG 3 DCC command programmer

After much deliberation and research I decided to purchase a SPROG 3 DCC USB computer interface with a 15V power supply so that I could use that with JMRI DCC control software on my old Asus Aspire One notepad to program the ESU unit. This unit will also allow me to programme locos and other stationary decoders in my workshop.

This system worked perfectly and now the ESU SwitchPilot Servo Version 2 works as I wanted, shutting off power to the servos about 6 seconds after they have stopped moving. Stiffness in the servo gearing is more than sufficient to keep the uncoupling ramps in their positions between activations.

Not the cheapest option at £80 for the SPROG3 and PSU I grant you, but it will be a useful tool for the future and a means of developing computer control of Die Keinnamebahn.