Undoubtedly the biggest issue with exhibiting two weekends in succession is that if something goes wrong during the first exhibition, there is very little time available to put things right before the second one.
Having come home on Sunday with a knackered switch panel and a seized EMU, priority was to get the switch panel fully operational. This meant ordering replacement transformers to replace the two that failed. The EMU wasn't so essential.
So late on Sunday evening, I bit the bullet and ordered a complete new set of transformers. I went with slightly more powerful ones, roughly 2.5 amps output, thinking that this would give me ample power for lighting, points, etc and would also be more than enough power for the controllers. Plus by standardising the transformers, it'll be easier to carry one replacement transformer that could be fitted in place very quickly should one fail again.
That was the theory. The reality has proved somewhat different.
So the transformers arrived on Thursday and I quickly got to work stripping the old Duette transformers from the panel, soldering in the shiny new ones in place. As the lighting and accessories were powered from a laptop power supply, a rectifier was needed to convert the power output to DC. A thermal cut-out has also been added as a precaution.
Now to test the controllers. All seemed well - no difference in power but it seemed the right thing to do to test under fault conditions, which will happen frequently. It was quite notable that the ammeters really kicked when put under fault conditions and the Trax controllers reacted far quicker than ever before. I was a little concerned but pressed on with testing, trying the fault condition test at a lower power level. That's when the smoke appeared from the back of the panel, followed by the familiar smell of burning PCB. Not good.
My function test had fried the shuttle controller and I had no spare. The transformers clearly are too powerful for the Trax controllers so less powerful ones are needed, and it's Thursday. The layout is out in two days. Time to panic.
After a conversation with Trax, they very kindly agreed to build and post a new controller by first class post (it arrived this morning) they also advised that 1.5 amps is the maximum power input for their controllers. But best of all, they were able to not only tell me which component was most likely to have blown, they also gave me the part number of the thyristor I needed and pointed me in the direction of my nearest Maplin. Having bought two thyrisors as a precaution, I very quickly had my shuttle controller back in operation, and of course I now have a spare one!
I don't think there are many companies around these days that would give that level of support, so if you're in the market for new controllers, I can't praise Trax highly enough.
Managed to track down a more sensible transformer, courtesy of Railroom electronics in Wareham and for now I've refitted the remaining Duette transformers so that I now have everything operational. I've ordered more transformers to eventually replace all the Duettes but this will get me through this weekend.
With that little drama resolved I still managed time to take a look at the blue & grey EMU. In fairness I hadn't expected much from it as I knew the magnet was weak. However it became clear over the weekend that there was more than just a magnet required. It sounded quite rough when running and there was visible movement in the bottom of the armature shaft, indicating that the bottom bearing had failed.
Whilst trawling Ebay for the transformers, I happened to see a trader selling the very bottom bearing I needed and another seller offering a remagnetised ringield magnet - far cheaper than a neo replacement and without the hassle of modifying to fit, also cheaper than buying a magnetiser!
I had concerns that I might have cooked the armature as the mechanism looked to be jammed solid. It seems to have escaped unharmed, the resistances across the three poles are all equal and after a quick commutator clean up, the new bearing and magnet were installed and the motor coach was spinning quite happily on the desk. It's passed the finger test but there wasn't time to track test so I'll find out tomorrow if my repairs were successful.
Fingers crossed that this weekend will be a little less eventful...
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