Adding the Bob’s Switch to the Cab04Ps for direction changing.

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Radio Cab04 Timeout Period adjustment, click here.

Programming the Option Button to be a Direction Button.

Turning ON the Cab04 radio with an ON/OFF switch.

On Board Chargers. Click on NCE Articles at Mark Schutzer’s site



Bobs Switch: When operating the Cab04 throttles, I always had to look down at the throttle and select either FWD or REV to change direction, no big deal you might say, but the Option button can be programmed to be a toggle direction button. I was experimenting in the Yard mode and I posted a message on the Yahoo NCE group about a problem I was having.


Bob Haggart in the U.S. replied with a message that he had set up an external momentary contact push button switch to control his locos direction. I liked the idea so I emailed him for details. The Bobs Switch details are at NCE Yahoo Files at KVRRs DCC Files and I have expanded on his details here.


This modification is really worth the extra effort. This really makes for a great throttle, my preferred throttle if operating trains without having to do any consisting. This throttle is especially useful for a visitor to your layout, where the Procab may daunt them with all the buttons, and I, like a lot of other model railroaders, prefer the knob. It gives you a feel for your loco.


See the notes about soldering if attempting small component and circuit board soldering for the first time.



Remove Cab04 knob, housing back and then the circuit board.


Locate option button pad on the circuit board (middle pad under the potentiometer).


As can be seen, these pads comprise of a series of parallel copper tracks and every second track is joined. When the button on the throttle is pushed down, a carbon impregnated dome comes in contact with these tracks and changes the resistance that the microcontroller sees for this input. Depending on how the microcontroller is programmed for this particular input, pressing the throttle button will cause an action. For example if the microcontroller saw this input with the resistance decreased continually as in the case with a Speed Button then the decoder would be told to keep increasing/decreasing the loco speed. In the case of our Option Button it is programmed as a TOGGLE (alternate action) input that obviously changes the direction.


Push two wires through the holes from the component side but not to exit holes on the keypad side to damage button pad.




The copper circles you can see all over the circuit board are holes that are lined with copper to connect copper tracks on the other side of the circuit board.


Locate the two wires and solder them on the component side as shown above, not on the pad side.



Cut the appropriate sized hole to fit the switch in the side of the case. The correct point will be approximately in the centre of the joint in the box halves.


Be careful when drilling holes in plastic. Increase drill sizes gradually so there is a less chance of ripping a hole. In this case, I used a file to complete the two half holes.











The momentary push button switch located in the cut out with the washer on the inside.


Note the flats on the switch housing to give enough clearance.


Ensure that the switch housing does not foul on any of the circuit board especially across some circuit board copper tracks. Place some insulating tape here.










The completed Bobs Switch Cab04.


With your thumb over the Bobs Switch for direction changing and your thumb controlling the knob for speed changes, this Cab04 throttle is now a one handed one thumb throttle.













Programming the Option Button to be a Direction Button.

By default, the Option button is programmed as a Direction button, so try your installation and see if it works. If not:


  1. Unplug your cab from the command bus or command station.
  2. Press and hold down SELECT LOCO button while plugging in the throttle. The throttle will now enter its internal setup program. This is indicated by a flashing of the status LED.
  3. Press 4 to enter OPTION key setup mode. Notice the flashing of the LED slows, indicating that it is ready to accept the key value.
  4. Enter the value of 67 for setting the OPTION button as a toggle direction control. Note this is the default setting of the throttle.


Note the OPTION button can be selected for many values, see instruction manual.


The Cab04P radio is normally set up, when operating in radio mode that it will turn off automatically with no throttle activity for 5 minutes. This can be adjusted between 1 and 9 minutes, normally.



Cab04 Radio Time Out Period adjustment.


Some time ago someone suggested, adjusting the Cab04 Time Out period, you had to swap the board into a Procab. While fitting the above Bobs Switch, figured I should just program the Option button to be the Expansion function as on the Procab as explained in the Cab04 instruction manual.


This feature would be especially useful if an external on/off switch was fitted as some modellers have done. Modifying the switch installation and removing a resistor as explained in the section Automatically turning on the Cab04 section below, will power the radio board as soon as the on/off switch is selected on. Setting the time out period to 0 will now keep the radio board powered till the Cab04 is selected off.


The radio boards for all cabs are the same. To set the period, the Cab04 has to be configured similar to the Procab that uses the EXPN button to access SETUP RADIO feature, where the time is set.


  1. With the Cab04 power off.
  2. Press and HOLD down the SELECT LOCO button while plugging in the Cab.
  3. The Cab04 is now in internal setup program and the keypad LED flashes.
  4. Press 4 to enter the Option button setup mode, the keypad LED flashes slower.
  5. Type 79 for Expansion Value.
  6. Press ENTER and LED extinguishes.
  7. The Option key NOW works as EXPN button that will give the same operation as the Procab. Page 5 of the manual.
  8. Unplug the Cab04.
  9. Press HORN to turn on the Cab04s radio. Transmission LED (adjacent to antenna) is now flashing.
  10. Press Option (programmed as Expansion). Transmission LED on steady.
  11. Press 2 the keypad LED is on steady.
  12. Press 0 to 9 for minutes of timeout. NOTE 0 for no automatic time out that is radio on all the time, then
  13. Press ENTER twice. LED extinguishes.


The Cab04 will now turn off automatically after the value you set in step 12 of cab inactivity.


Now you have to re-program the Option Button to your desired function. Many operators would have been using the default setting for the Option button that makes it a DIRECTION toggle or any other feature on page 5.


  1. With the Cab04 power off.
  2. Press and HOLD down the SELECT LOCO button while plugging in the Cab.
  3. The Cab04 is now in internal setup program and the keypad LED flashes.
  4. Press 4 to enter the Option button setup mode, the keypad LED flashes slower.
  5. Press 67 for DIRECTION or your desired value.
  6. Press ENTER.
  7. The Option key NOW works as DIRECTION button or whatever you have set in item 4.
  8. Unplug the Cab04.


NOTE: With the timeout period set to 0 (no auto turn off) you must plug the Cab04 into the Cab Bus to turn off the radio. Or next time the batteries will be flat for sure.


Using an ON/OFF Switch to TURN ON Radio Throttles.


Some modelers have fitted an ON/OFF switch to their radio throttles to extend the battery life. With the throttles off, there is a constant drain on the 2 or 4 batteries (depending on model) due to the standby circuitry of the throttles.


I use NiMH rechargeable batteries and have fitted a charging socket that can be seen in these web pages, so I don’t worry about the constant discharge. NiMH and NiCd batteries have a much higher self discharge rate than dry cells so even if they were switched off with a switch, they still discharge.


Bob Foltz, a member on the NCE Yahoo group has placed a photo at Yahoo Groups in the Photos section that suggests removing a resistor and fitting the ON/OFF switch wired into the white and brown wires. This will allow the radio board to turn on automatically when the on/off switch is selected on. No more 3 o’clock pressing of the EMERGENCY STOP button and waiting for the display to come up. It all happens.




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