R8249 in GWR goes backwards

[kiwikezza]

Hi all,

I've installed a R8249 DCC decoder in a GWR class 060 shunter.

But it will only go one way, backwards.

I've checked the wiring which is the right way.

All other locos with the same chip go both ways.

Any ideas what I am doing wrong?

[96RAF]

With the DC blanking plate fitted the loco should go forward when positive is applied to the right rail and negative to the left. Simplest way is to apply a 9v battery to the rail ends.

If the loco reverses then swap the two wires to the motor over.

To avoid soldering wires and if your controller allows it adjust the value of CV29 to reverse the default direction. Use an on-line calculator to find the correct value. If you can read values then obtain the current value and put that into the calculator then reverse the direction flag accordingly.

[ColinB]

It sounds like you have a broken decoder. If one of the elements of the H bridge which is the output of the decoder, is broken you get this effect. I bet if you turn the decoder plug around in its socket, the loco will only go forwards.