Troubleshooting

If you can’t get your motor controller to work, here are some troubleshooting steps that may help you find the problem;

General problems:

  • Is the “high pot lockout” feature activating? [not Porter or DNO].
  • Are the fuse tracks on the circuit board ok? see the manual for details.
  • Has the pot been replaced? We consider pots to be a bit like car brake pads, they have a spring loaded metal arm which presses on a carbon track and will eventually wear out.
  • Are the control cable plugs in good condition? The damage shown in this picture can cause intermittent problems as the internal pins can short out ….

poor IDC connection

 

 

They’re cheap to replace, and can be ordered here.

 

 

 

  • One last point, we’ve also learnt that the majority of mosfet failures are due to suppression components not being fitted. If you haven’t already done this……you should.

If you need help with troubleshooting we’re happy to help but please before you contact us, download and complete the relevant fault finding sheet [see below], it will help us get you running again a lot faster.

We’ve recently created a controller test board, it works by temporarily taking the place of the normal control wiring, and helps to identify and isolate problems. We’re making these available free of charge to all model locomotive clubs, and they are also available for purchase here.

Here are some some model specific fault finding guides…..

DNO, Pro, and VTX models

First print off the relevant fault finding sheet…. DNOPro-150Pro-120 these list the voltages you should expect to find and give an indication of the problem if they are wrong.

Remove the controller cover.

Check the fuse tracks [see manual for location].

Now plug the control cable back in, then check the following voltages on the back of the grey 6 way connector. Note: for the DNO take care not to press the PCB so that it shorts on the metal heatsink.

troubleshooting

Wire colour Voltage [with respect to B-] If it’s not….
Green 0 Wiring fault or blown fuse track
Blue 0 – 7V [Pro-150=5V] changes with pot position Wiring or pot fault
Red Approx 7V [Pro-150=5V] Wiring or controller fault
Black 0 or B+, changes with reverse switch Wiring or switch fault
White 0 or B+, changes with ignition switch Wiring or switch fault
Yellow B+ Wiring fault or blown fuse track

Here’s a video showing how to do this on a  Pro-120

4QD-200 / 300 models

First check that the various jumpers on the control board are set correctly for your application.

Check both the fuse tracks, there is one per board, see here for their location.

Now print off the fault finding sheet,  this lists the voltages you should expect to find and gives an indication of the problem if they are wrong.

Check the following voltages on the pins of the grey 6 way connector on the top board.

testing the 4qd-300

Pin letter [wire colour] Voltage [with respect to B-] If it’s not….
A 0V with ignition off,             11V with ignition on [0V if inhibit activated]
B 0V with ignition off,             11V with ignition on Wiring or controller fault
C [Black] 0 or B+*, changes with reverse switch [* can be 11V if alternative wiring used] Wiring or reverse switch fault
D [Red] Approx 11V Wiring or controller fault
E [Blue] 0 – 11V, changes with pot position Wiring or pot fault
F [Green]  0V  Wiring fault or fuse track blown

Also check the following voltages on the grey 4 way connector on the bottom board

Pin letter [wire colour] Voltage [with respect to B-] If it’s not….
A
B
C [White] 0 or B+, changes with ignition switch Wiring or switch fault
D [Yellow] B+ Wiring fault

We also have some general fault finding tips for the 4QD series here, and some instructions on how to test the base board and MOSFETs here.

Porter 5 / 10

First print off the fault finding sheet.. this lists the voltages you should expect to find and gives an indication of the problem if they are wrong.

Remove the controller cover, plug the control cable back in, then check the following voltages on the pins of the grey 5 way connector on the board.

Pin letter Voltage [with respect to B-] If it’s not….
A 0 – 0.5V Wiring or controller fault
B 0 – 0.5V Wiring or controller fault
C 1-4V, changes with pot position Wiring or pot fault
D 5V Wiring or controller fault
E 5V Wiring or controller fault