Effects of motor capacitor?

[Wobblinwheel]

I have two brand-new Hornby locos, each with caps soldered to the motors. I hear many say they should be removed for DCC. What are the negative effects if I don't?

[2e0dtoeric]

The capacitors are there on dc loco's to 'suppress' any tv interference the motor might make when it is running.

With a DCC chipped loco, the capacitor will merely interfere with the motor electromagnetic pulses that the chip reads, to see how fast it is turning.

A 'stay-alive' capacitor is a different beast, connected in a different place in the circuit.

The capacitor in a dc power track is also there to prevent tv interference. On a DCC railway, it will corrupt the dcc signal that is being passed from the controller to the track.

[dynax]

 if that's the case why do dcc fitted loco's still have them on

[walkingthedog]

Perhaps they don't actually do any harm and if you removed the decoder and fitted a blanking plate you would have to add a capacitor. 

[Wobblinwheel]

When removing the capacitor, do you just clip and remove, or does a jumper have to replace it? Could this be why my DCC fitted Mallard has a slight "surge" to it? The new one "Golden Shuttle" does the same thing with the Hornby P.O.S. decoder in it. You can notice the last coach (at the coupling) shifting fore-and-aft as it's being pulled along. The "Keep-Alive" decoder helped immensly on Mallard, but it's still noticeable. Both still have the caps on the motor. (that is the little brown disc-like "thingy" attached to the back of the motor, right?)

[walkingthedog]

Clip it off. If you replaced it with a jumper I believe you would have a short circuit. 

[poliss]

The DCC fitted locos with capacitor have been tested to work with them fitted.

Early decoders didn't have on board RF suppression. Modern ones should be ok without the added capacitor.

You're correct WTD. It would cause a short circuit.

[2e0dtoeric]

Wobblin - the surging back and to you comment on is caused by three things, a long train, the slack in the couplings (that isn't there in real life), and the low weight and rolling resistance of the stock. In the days of loose-coupled stock, and no brakes except at the brake van and loco, surging stock was common, as they went over a crest and down the other side, or stopping and starting - sometimes resulting in such a snatch at the brake van that the guard was thrown out, or the chain coupling snapped.

[Wobblinwheel]

Clip it off. If you replaced it with a jumper I believe you would have a short circuit. 

I see that now, after looking at it. A jumper would surely be a "boo-boo"!

[Wobblinwheel]

So, what (if any) are the actual, "visible", possible effects of having the capacitor on DCC? Why do we cut it off?? What are the VISIBLE signs that "it's gotta go"!??

[poliss]

Erratic running Wobbly, especially at crawl speeds. If the loco runs well with them in place, then there's no need to remove them.

If your neighbour is getting interference on their TV or radio, then put them back. :-)