Hello all.
Power supply: Tech 2
Scale: HO
Layout: DC
Locomotive in question- Spectrum (Bachmann) Light Mountain 4-8-2
Days with issues: 2
I've owned my 4-8-2 Light Mountain for about 3 years now, and just yesterday it's emitting a rather loud humming noise while running from what I suspect is the motor. Note; It only does this in forward AND while the DC power pack is on "pulse." It does not seem to affect performace any, just noise. Also note; this is the only locomotive it does it on. Direction (on the layout) does not matter either. As long as the locomotive is going forward and the power pack is on "Pulse" I get the humming noise.
Any thoughts?
Thanks
Modeling the N&W freelanced at the height of their steam era in HO.
Daniel G.
Most HO engines made since about 2000 that are "DC" engines actually come with a lightboard that has some type of receptacle to plug in a DCC decoder. IIRC, some of the lightboards don't like pulse power...or, some lightboards don't like certain types of pulse power.
That all being said, if the engine and power pack played nicely together in the past, I don't know why it would just start 'acting up' now...assuming nothing else has changed on your layout.
turn off the pulse ?
In order for Bachmann to comply with E.U. standards they include a radio interference "choke coil" which amounts to a couple of capacitors and either a ferrite rod or torodial choke coil.
https://sites.google.com/site/markgurries/home/technical-discussions/decoder-motor-drive/motor-capacitors/bachmann-engines
For others using DCC this can play havoc on decoders, especially the "back EMF" circuitry.
I suspect this choke may also be contributing your humming when using pulse-power. Pulse power is half-wave DC and should only be used to get the engine moving, then switched off once the engine is under way. Continuous use may cause excessive heat in the armature. Essentially, it causes the armature to vibrate.
If you have used the pulse-power in the past and the engine is giving you trouble now it may be beacuse the heat has melted some of your armature windings, or these RF capacitors are going bad or the motor bearings are wearing out or need lube and are causing the increased buzz/hum or a combination of all three.
http://www.nmra.org/beginner/wiring
Scroll to paragraph 5 under Power Packs. The "pulse-power" setup was really designed to help those old open-frame motors, some were only three pole, to overcome "cogging" between the poles. A newer can motor would probably overheat right away.
Good Luck, Ed
Hey, thanks. It does run better at high speeds w/o pulse. I didn't know pulse was only for low speeds then needs to be shut off. I'll be running the locomotive (and all of them for that matter) pulse-off.
Thanks for the link and for the reply. I appreciate it.
I have seen the same suggestion in the Bachmann forums from a Bachmann rep.
Don't use pulse power.
Another thought. Have you used pulse power in the past and it was not noisy?
There might be a mechanical wear issue that pulse power reveals.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.