Noise suppression devices on locos remove for DCC operation.

Mark Gurries wrote on 15 Jun 05 in response to a question about a loco loco directional differences and the modeller suggested removing capacitors fitted to Rivarossi circuit board on the problem loco.

Murphy's Law: A locomotive will always run better in reverse.

I agree with Allan. Try breaking in your locomotive first, under DC if you must, will remove that as being a factor. Make sure the wheels are clean again when you get done before you install the decoder..

Allan is also right in that a capacitors do not effect decoder operation in terms of direction. It can, however, effect decoder operation

overall and independent of direction.

Many locomotives seem to come with some filtering electronics for the motor. This filter circuit often consist of a ceramic capacitor and one or two stick inductors. It exist because some locomotive manufacture are attempting to reduce the "Radio Wave" interference the motors can create when they run. Think motor noise & static noise you get on the TV or Radio type of thing. They add this filter to reduce the interference to comply with some regulation agency that regulates such things. To be clear, most locomotive manufactures have NO filter circuit at all.

The filter circuit was intended to be used with the engine while operating in DC mode as opposed to DCC. As people have found, DCC decoders were not designed to work with these filters. In many cases it has lead to erratic operation. The recommendation is that for DCC, at a minimum the capacitor should be removed completely (clipped out). Removing the whole filter is required if you use a decoder with BEMF.

Best Regards,

Mark Gurries

Linear Technology

Power Supply & Battery Charger Applications Engineer/Manager

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