Hey guys,

I had a fairly upsetting experience recently with one of my Bachmann Spectrum locomotives. I had a pair of E33 rectifiers running a short freight around the club layout, when one of the engines just quit and died right there.

This engine I've never played with anything apart from putting a decoder in the top hatch. I thought maybe the decoder fried, (and it looks like it did), but I found that even on DC, the engine didn't run properly, especially in reverse.

Not only was the decoder down, but the motor and the PC board were fried. When run in "reverse", the motor will not turn at all (or if it does, it will jolt briefly and die), and even with the motor cut out from the engine, the rear headlight does all sorts of crazy things when I advance the DC throttle.

This tells me something died in the engine and took my decoders with it (I made the mistake of trying a new decoder, which destroyed that one as well).

The decoders now malfunction when going in reverse, eventually shorting out when in reverse, even in a healthy engine.

Why would this happen? I can't find any burn marks or issues on the decoder or PC board, but something isn't right.


It will cost me at least $34 in parts to repair, plus shipping and the cost of shipping my burned out TCS decoders for warranty replacement. Its making me just a tad angry.

Rather than get to upset, I wish I had some insight as to what happened so I can avoid it in the future.

Did something go wrong in the gear towers of one of the trucks? Is there dirt inside perhaps?
It could be that dirt or other malfunction makes the gears run with more resistance in one direction, and not the other. This could perhaps have overloaded the motor and fry it?
It is very hard to diagnose 'remotely', especially without any pictures and perhaps other information. At first, I'm calling a mechanical issue being at the root of this, as everything happened in 'reverse' direction, and not the other...

torikoos Wrote:Did something go wrong in the gear towers of one of the trucks? Is there dirt inside perhaps?
It could be that dirt or other malfunction makes the gears run with more resistance in one direction, and not the other. This could perhaps have overloaded the motor and fry it?
It is very hard to diagnose 'remotely', especially without any pictures and perhaps other information. At first, I'm calling a mechanical issue being at the root of this, as everything happened in 'reverse' direction, and not the other...

I might have gone for the mechanical explanation, but I was able to freely turn the drive by hand.

Furthermore, the motor will not run in reverse even when disconnected from the drive (as in, spinning freely). It turns freely by hand, but not under power.

Did you run across any points that might have reversed polarity and shorted something?

Green_Elite_Cab Wrote:I might have gone for the mechanical explanation, but I was able to freely turn the drive by hand.

Furthermore, the motor will not run in reverse even when disconnected from the drive (as in, spinning freely). It turns freely by hand, but not under power.

In that case, I would suspect that your carbon brushes are worn/damaged and may have moved so that they are jamming against the commutator of the motor, and the brush holder. The commutator has small 'gaps' which spinning in one direction may pass the brush smoothly, but in the other direction perhaps cause the brush to jam it somewhat. If you can turn the motor by hand, you may be able to feel or hear this, as one direction it will be smooth (ish), the other you may feel it jamming up or hear it ticking when you turn it.

In any case, take out the brushes, clean out the motor with compressed air ( air from an airbrush will work for example), and before re-installing (new) brushes, feel if it rotates ok in both directions. Look for physical damage. If all is well , a few drops of lube on the motor 'bearings' and you can try again.

Actually re-reading your post again, you wrote there's no problem with motor spinning freely (unless the offending 'brush' perhaps has already shifted due to the handling. There might now not be a brush that is properly seated, a slight movement will cause it to loose connection one way, and 'just' the other direction. In any case, check it all over. If you can get the motor to run ok in both directions on DC (with a pair of wires attached to a power pack) then it should be fine for DCC too. I left the above 'jam' scenario for info purposes.

Koos

Test the engine by removing the decoder and replacing it with the "plug" that came with the engine. It should run. Rarely will a motor burn out due to a faulty decoder.
B'mann decoders aren't worth a pitcher of warm spit. I have several B'mann engines and before I test them I replace them with the DC plug that should have come with the engine. If the engine works OK with DC, the mechanics are OK.
Once the testing is done with, I install a Digitrax decoder, do a preliminary "program", and go from there.

Hope this helps.

torikoos Wrote:

Green_Elite_Cab Wrote:I might have gone for the mechanical explanation, but I was able to freely turn the drive by hand.

Furthermore, the motor will not run in reverse even when disconnected from the drive (as in, spinning freely). It turns freely by hand, but not under power.

In any case, take out the brushes, clean out the motor with compressed air ( air from an airbrush will work for example), and before re-installing (new) brushes, feel if it rotates ok in both directions. Look for physical damage. If all is well , a few drops of lube on the motor 'bearings' and you can try again.


Koos

The bad news is there is no way to gain access to the interior of the motor without damaging it. The good news is that a new motor costs $4. The real price is the PC board, but the more I think of it, the more unecessary it seems. I might be better off hardwiring the thing, and maybe adding some weight in its place. The only loss of function would be the loss of pantograph power, but thats not something I use anyway.

Steamtrains Wrote:Test the engine by removing the decoder and replacing it with the "plug" that came with the engine. It should run. Rarely will a motor burn out due to a faulty decoder.
B'mann decoders aren't worth a pitcher of warm spit. I have several B'mann engines and before I test them I replace them with the DC plug that should have come with the engine. If the engine works OK with DC, the mechanics are OK.
Once the testing is done with, I install a Digitrax decoder, do a preliminary "program", and go from there.

Hope this helps.

Actually, the decoder was a TCS DP2X, which is fairly reliable. I did try running the engine on DC with the DC jumper plug installed, and it had all the problems outlined in the first post.