Problem with Aristocraft motor blocks; RS3's, F1A & U25b due to short curcuits? derailment

G

Geoff the garden nav

Aristocraft locos & rolling stock, mid C20th to co
I recently wondered why one of my U25b's was stalling / faltering on points, its been quite a hard winter, the track could be cleaner and probably the wheels. Back indoors with the loco carefully turned upside down I did a test with power directly onto the the wheels to see if all the wheels were picking up power. Sure enough one set of wheels per motor block were dead. Opening up the motor block reveled that the one of the thin copper wires from the axle without the universal joint, had fused, burned out presumably due to a short circuit, resulting from a derailment? checking two other later U25bs and a nearly new RS3, each had an axle with a similar problem. I have cleaned up the copper wires, stretched it out a little from the abrupt 90 degree bend near to the screw terminal and silver soldered the ends back together with an overlap, so far so good. A continuity test with multi meter between pairs of wheels on the same side of the motor block quickly reveals the problem. Is this common? I use an Aristo train engineer in pulse width mode with a 10 amp Crest power supply, presumably this is the result of short circuits which didn't blow the inline fuse! and damage which went un noticed at the time, is this a well known problem with this type of motor block? something to watch out for.
 
One or two locos do have wiring issues: I have read about this over a period of time. It is likely, as you suggest, that a derailment caused your problem.

Many friends Stateside only use a 5A fuse in their Train Engineers, especially those who use battery power.

I run RS3's and Centre Cabs here. Both Train Engineers (27MHz. version) which I use - one for battery the other for track power - are fitted with a 2.5A fuse. Fuses are cheaper than loco motors. ;) In two years use, however, I have never had a fuse blow.
 
Thank you for the suggestion about fuses, I will be more careful about apparently minor derailments! I carnt help thinking that an easily re placeable onboard fuse or miniature circuit breaker would be a good idea. I am also surprised these apparently robust locomotives with ball bearing power pick up on the motor blocks going back to 2002 have such a weakness. It doesnt really protect the motor because the other axle will still picking up power if in contact with the rails and wheels will keep turning! The older Aristo power pick ups from this type of block were a simple hollow brass bush or spring loaded bush in the side frame with a big wire connecting them together, no chance of those burning out.

Haven't seen inside a 3 axle Aristo motor block, I wonder how the power picks ups are wired together in these?

Geoff the garden navvie
 
Geoff the garden nav said:
Haven't seen inside a 3 axle Aristo motor block, I wonder how the power picks ups are wired together in these?

Geoff the garden navvie
Click to expand...

On the Dash-9 each axle has two pickups, one each side, they look like small round shims that rest against the ball beaings.
Each side the three pickups are joined by a busbar that lays externally on top of the gearbox, each bar has three prongs that reach into the gearbox and contact the shims. The busbars then connect up through to the board inside the body.
The busbars look quite substantial so would be hard to melt them but the wiring to the board may be a different kettle of fish.
 
The Devonian said:
One or two locos do have wiring issues: I have read about this over a period of time. It is likely, as you suggest, that a derailment caused your problem.

Many friends Stateside only use a 5A fuse in their Train Engineers, especially those who use battery power.

I run RS3's and Centre Cabs here. Both Train Engineers (27MHz. version) which I use - one for battery the other for track power - are fitted with a 2.5A fuse. Fuses are cheaper than loco motors. ;) In two years use, however, I have never had a fuse blow.
Click to expand...

For the car type fuse in the TE make sure you get the quick blow variety.
I have the 10Amp quick blow and have had no problems.
 
Geoff,
This is/was a problem for the early Aristocrafts. I have 3 U25B's and FA anad FB. By now all of those soldered pickups have been resoldered. I was having the same problem, removed the first 4 sideframes, 4 of 8 were burned out. Club members say production used cheap solder. They been doing great since I repaired them.
 
Another point for consideration is to run on 18v rather than 24v, Aristo locos seem to prefer this - no burn outs and no fuses popping unless of course you bridge the track
 
[align=center]I have been thinking of a method to fit new pickups on the outside of the gearboxs with wiper s made of flat phospher bronze, we used to do this in HO but those loco were not drawing the current these do, quick blow car fuses are good, I now fit 2 amp in the locos and 10amp in the supply feeders, I often blow the feed ones if there is a derailment, saves the locos and the chips tho,.there seem to be a lot of variants about of the motor blocks the newer ones I have are better made, Greg's website has a list to help identify them and mentions about these thin wires
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