WHEN: Most Friday evenings. TIME:

09 April 2010

Simple controller checker for three pin plug type

Given my infrequent trips to Ecurie and distance involved, any transistor controller repair or development had ground to an effective halt as a consequence of the tedious delays in testing the units. A simple diagram off the British Darkside slot car site (see link at bottom) suggested that the new three pin plug and socket system now provides an excellent opportunity for a simple test unit.

A chat to Erlo and a tip from flying buddy Mark lead to the purchase of the white 5amp three pin plug socket shown at the left. I flirted with retaining the US controller three colour red/white/back approach but then decided I would stay with black/red colour shown for intuitive ease of hook up to the DC power supply source and test motor/car. When I can actually locate the Brit diagram drawn to controller colours on the net again, I will add that but for now it is actually easier to tell than draw:
1. Two negative black wires twist together and connect to the earth E (bigger) terminal [controller red]. One negative black lead connects to the DC power source and the second negative black lead connects to the test motor or car left negative braid.
2. One positive red wire connects to the live terminal [marked "L" - controller white] and across to the positive lead of the DC power source.
3. A second positive red wire connects to the neutral terminal [marked "N" - controller black] and across to the test motor or car right positive braid.
That's it! The DC source can be max 13.8 volts DC right down to my 8 volts DC unit Lance made us for Dremel cutters etc and worked fine in my case. Obviously mounting the 5 amp socket in to a box would be the next step.
The controller in the second pic down is Jono's, which was a basket case example of why unravelling insulation tape is a poor second to heat shrink tubing. Both adjustment pots and the NPN transistor had been changed without success but it was suspected that the thin red wire to the insulated wiper may have fractured internally under movement load or the intense heat when the the controller cooked. It was simple exercise to check, replace and immediately test the controller on the new tester - with great success. Those up the north coast may have heard the cheer at midnight last night ;-)
The controller savvy folk will by now have twigged why the German slot car racers insist their controller cable colouring is correct and the more common US colours incorrect. Our red "brake" cable is in reality the negative (black) common feed from power source to car!
Now that I at last have this bogey controller repair sorted, I can aim to finish off Nigel's new MRRC project...... ;-)
The useful "build a simple controller checker" article located here:

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