Anniversary 4-6-0 tender light flickers in forward

[jviss]

Greetings,

I am the recent new, proud owner of an Anniversary D&RGW "Bumble Bee" 4'6-0 locomotive.  I'm using it on a relatively large, indoor, steel sectional track layout (over 100' of steel track).  I am powering it with an MRC Trainpower 6200 which is rated, in Mode I 0 to 18.5VDC and 18VAC for accessories to 60A max.  I'm not using any accessories.  I've seen much higher voltages, though, at full throttle, up to 24V or so.

When driving the train forward, the light on the tender flickers.  Does anyone know why this might occur?  I was thinking that the only way that's possible is if the power pack is controlling output using pulse width modulation, and the output is making negative excursions. 

Thanks,

jv

[Joe Zullo]

Dirty track/dirty wheels will cause this. The rear light is seeing small drops in the voltage (going negative) enough to fool the LED to thinking it is going in reverse. I occasionally see this happen on my RR too with all my locos. 

[Joe Satnik]

Dear All,

The cause of the rear LED flashing is inductive kickback, which occurs when electrical contact between the track and the motor is lost.  

If the front light is also an LED, you should be able to see it flashing while running in reverse.  

http://www.bachmanntrains.com/home-usa/board/index.php/topic,28257.15.html   See my post about half-way down the page...

So, the only way to minimize the flashing is to have good contact between the track and motor, which means having:

1. Clean wheels.

2. As many wheels picking up track power as possible, with all their pickups functioning properly.

3. Clean track.

4.  A thin layer of Wahl clipper oil to help minimize arcing between the track and wheels.

Hope this helps.

Sincerely,

Joe Satnik

Edit:  Added Italics

[jviss]

Thanks, guys, for the replies.  Joe S., I suspected that after reading Joe Z's reply, since a dropout wouldn't cause a negative excursion, unless there was some charge stored somewhere on the loco, and yes, the spinning motor which is nearly entirely inductive would do that; you can't change the current through and inductor instantaneously, as they say.  It could be solved with the addition of a Schottky diode and load capacitor across the motor, but I'll have to investigate a dual-polarity solution.

4.  A thin layer of Wahl clipper oil to help minimize arcing between the track and wheels.

Is this the same thing as the conductive oil Bachmann sells?  I'd like to treat my new Bachmann steel track with something to prevent corrosion, and a conductive, light oil would be ideal.

Thanks,

jv