Hello I am New to to this group
I have a new Rivarossi Heisler locomotive,into which I plugged
a Digitrax dz143pn decoder. In reverse it runs great,however in
forward it runs poorly,it jerks along and takes more voltage to get it
to start.
I have asked in other forums and got some feedback about the circuit
board ie cutting out some caps,but have upon examination that it has
alot of surface mount componates. Any ideas?
Thanks Stephen

Stephen,

Capacitors will never be responsible "directional differences." So
you can forget about removing them. Also, I suspect that if
Rivarossi provided a plug for a decoder they didn't intend for you
to need to remove any components from their circuit board.

Your problems sound mechanical. If you want to prove it to
yourself, remove the decoder and reinstall the dummy plug that came
with the locomotive. Put the locomotive on a track running from a
regular, DC power pack. It will probably perform just as poorly.

Maybe your locomotive just needs to be broken in. Perhaps it has
something else wrong with it. In any event, it isn't a DCC problem
and is beyond the scope of this DCC forum.

Allan


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

Stephen,

Capacitors will never be responsible "directional differences." So
you can forget about removing them. Also, I suspect that if
Rivarossi provided a plug for a decoder they didn't intend for you
to need to remove any components from their circuit board.

Your problems sound mechanical. If you want to prove it to
yourself, remove the decoder and reinstall the dummy plug that came
with the locomotive. Put the locomotive on a track running from a
regular, DC power pack. It will probably perform just as poorly.

Maybe your locomotive just needs to be broken in. Perhaps it has
something else wrong with it. In any event, it isn't a DCC problem
and is beyond the scope of this DCC forum.

Allan


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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