South Downs Railway

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Bachmann Voyager fixed!

I've fixed the Bachmann "Voyager" today: so we now have a near completely working set of locos.

The fault was: as soon as it started to move, the track power was shorted and the PM42 isolated the track section. I'd removed the power car, replaced the DCC decoder with the original "DC" plug, then powered it from a 12v supply. The motor ran slowly, but took 2A. After a while it sun up to full speed and only took 150mA, and all was well for a month; then it did it again.

This time I removed the bogies to eliminate a mechanical load as the cause. Still it took 2A. I stripped down the chassis and removed the motor completely. It still took 2A, then spun up to full speed again - so definitely the problem was in the motor.

BR Lines were able to supply me a new motor, but then everything went wrong....

The new motor was 1mm shorter than the last one; that meand that one of the drive shafts didn't mate with the motor and a bogie wasn't driven. It looks like the flywheel has been pressed too far onto the axle. No problem - the plastic insert could be pulled out 1mm so the drive shaft could still be driven.

The old motor had a piece of foam around half of it. The purpose of that foam is to make sure the PCB can't short to the motor body. Unfortunately I didn't note which side of the motor it was on, and assembled the model with the motor upside down. Result - loco runs forward, with red light lit; white light for reverse.

I was able to use 12V DC with little wires to contact the motor and test it. After installing the PCB I did the same test, and the motor appeared to run OK.

The phosphor bronze strips that contact the motor from the PCB were slightly bent, and could short to the chassis. So when it was all re-assembled the forward/reverse LEDs worked OK but the motor wouldn't run. I believe it had a motor shorted to the rails. I assumed the problem was the previous short having caused the decoder to fail, so I fetched another.... similar result, this time with a burn mark on the decoder's heat shrink.

The ESU decoder tester was invaluable at this point: essentially a "known good loco" into which you plug any decoder. Unfortunately they hadn't marked pin 1 (they'd helpfully written "yellow" on what turns out to be pin 6). After resolving that the new, cheap decoder was definitely failed in one direction (it still ran in the other) but the Digitrax one was OK. Clearly the Digitrax ones are more tolerant of operator abuse.

Finally, with the motor contacts clear of the chassis and a good decoder in place, I was able to get the loco back on the track. That took an hour and a half, to do a 10 minute job!

Lessons: there's value in things like decoder testers; but getting the basics right is fundamental.

 

Dapol Voyager Fixed?

We've often had trouble with the Dapol voyager. At one point it was returned to Dapol and came back running very well, for a while.... but then it reverted. A complete inability to negotiate pointwork was the problem - it would just derail at any opportunity.

 

I decided to put it back on the rails car by car, starting with the central power car. As I added each one, I checked that the bogies were free and the wheels had correct back-to-back settings. The power car, other central car and one front carriage went OK. But the other front carriage had a bogie problem: it was obvious that one axle wasn't properly staying in the phosphor bronze end caps.

Using a micrometer it was clear that the axles lengths were the same, but one bogie end was 0.5mm wider than the other. 0.5mm on an axle is a huge difference. Looking closely at the construction, the side frames seem to be some kind of pushfit into spigots on the central part, and one wasn't pushed in fully. A pair of long nose priers rectified that, and both ends then had the same width.

The train now seems to run OK round the railway. For a while it had pickup issues but after running for a few minutes it seemed to get past those. Hopefully it is fixed!

Annie and Clarabel

We have the Tomix "Thomas the Tank Engine" set. Thomas has a decoder installed and (once the chassis was put back together properly) runs quite well. In principle, Thomas could run on a sequence of schedules and visit any through or terminus type platform.

However, there is a catch: Annie and Clarbel have plastic wheels, so we can't add resistors to the axles for detection. The result is, Traincontroller can't detect the train reaching the end of a terminus block if the train is running with thomas at the rear.

The model seems to be significantly out of scale: it is (probably for artistic reasons) significantly bigger than you'd expect. The running wheels for Annie and Clarabel are 8.9mm diameter (10.2mm across the flanges); typical wheelsets that we can get are nearer 6mm. It would look badly our of scale simply putting smaller wheels in place of the provided ones. as I recall, the axle length is also different from those we have access to.

There could be several solutions, for which we don't yet know the best way forward:

  1. Get a suitable wheel set made on a "bespoke" basis by a competent metalsmith
  2. Find a "near equivalent" that fits the existing axle (1.49mm diameter, approx 1/16")
  3. Replace the chassis for Annie and Clarabel by a different chassis that we can get wheels for. The chassis is 20.3x62.9mm.

Any ideas anyone?

Tomix Track Cleaner

This is the Tomix track cleaning truck, sold in UK by Dapol.

tomix track cleaner

It has been modified for DCC by putting a decoder inside the body. I've used a "function only" decoder I had lying around, but a plain loco decoder would be fine. It is assigned to the loco number of its prime mover loco, and operates as function F1.

Santa Fe visitor

This is a visiting locomotive, all the way from New Mexico!

santa fe sd45

Purchased on a visitto a model shop in USA, as a "I'll need to buy something having been here so long" kind of thing. It pulls the track cleaning truck, which operates on the same DCC number on loco function F1.

A Digitrax DN135 decoder is fitted. This is slightly larger than most N scale decoders nowadays, but fits easily. It is solvered to the PCB with the wire numbers clearly marked; the decoder fits under the PCB.

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