Troubleshooting

If you can’t get your motor controller to work, we’ve found that following these troubleshooting steps often helps to find the problem;

General problems:

• As a starting point measure the voltage across the battery terminals.
• Now measure the voltage across the controller B+ / B- terminals – ideally do this under load,  it should be the same as the battery voltage.
• 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.
• If you are getting P2 or P3 pot faults, or odd low speed behaviour, has the pot been replaced? They do wear out, see this page for more details.
• Are the control cable plugs in good condition? The example in this picture caused all sorts of intermittent problems as the internal pins shorted out ….

 

 

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

 

 

• One last point, the majority of mosfet failures are due to electrical noise from the motor brushes. We strongly advise fitting suppression components  and making sure your installation follows these guidelines.

If you need help with troubleshooting we’re happy to talk, but before you phone us, please download and complete the relevant fault-finding sheet from the sections below. Without that information we’ll be flying blind, having it ready will help us to get you running again a lot faster.

We also have a controller test board, it works by temporarily taking the place of the normal control wiring, and helps to identify and isolate problems. These are available free of charge to all model locomotive clubs, are available for purchase here, and can be loaned if required. Here’s a list of all the clubs that have one.

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

DNO, Pro, and VTX models

• Print off the relevant fault-finding sheet…. DNO, Pro-120, Pro-150, Pro-160/360, 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.

Wire colour	Voltage [with respect to B-]	If it’s not….
Green	0	Wiring fault or blown fuse track
Blue	0 – 7V [Pro-150/160=5V] changes with pot position	Wiring or pot fault
Red	Approx 7V [Pro-150/160=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-150…

On the DNO…..

And here’s another for the  Pro-120

 

4QD-200 / 300 models

• Check that the various jumpers on the control board are set correctly for your application.
• Check that the under voltage protection pot is set correctly for your battery.
• 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.

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	0V with ignition off          0.5V with ignition on	Wiring or controller fault
B	0V with ignition off               0V with ignition on	Wiring or controller fault
C	0.5-4.2V, changes with pot position	Wiring or pot fault
D	5.5V with ignition off             4.8V with ignition on	Wiring or controller fault
E	5.5V with ignition off             4.2V with ignition on	Wiring or controller fault

• Note: These values are for a Porter with a 10k pot connected to pins A, C, and E. Values may change slightly for other input configurations.