I have a 37 Class diesel which I converted to DCC many years ago, for some reason it's dead, my question, is there a way to check the fitted Loksound decoder, also, if I remove the decider, would the loco run on a DC track, just to check the motor and connections etc?

As you know Phil, I'm an expert at these things - as in:  an "ex" is a has-been and a spurt is a drip under pressure ……………….

However, assuming it's a plug in decoder, you'd have to replace that with the original blanking plate to take it back to it's DC days.  I don't think it would run without that blanking plate - it makes the necessary connections.

Thanks Peter, tried with power to the wheels but no go, power straight to the motor works, the problem is,I have no idea where the blanking plate is?

Nothing has been done to the loco to cause bad connections etc, it was working on the track, a few weeks later it's not!

Do you have any blanking plates Phil ?  Not at all sure but maybe a plate from the same manufacturer might do the job ……………..

However, I'd wait until a better qualified expert than I offers some advice - I'd probably blow the motor up !!

Power to the motor suggests it could be a dead decoder.  Have you tried taking it out and refitting it ?  It could just be an iffy connection on the pins.

Hi Phil,

1. Check that the decoder is readable by your DCC controller in programme mode using the DCC test track. Make and decoder codes should come up. If yes it is electrically connected. If not it's either dead or not connected.

2. Check that the wires to the decoder from the pickups are not disconnected. You will need a multimeter to do this. Easy to do if hard wired. If coming through a socket remove decoder and replace with the blanking plug. This just connects black to grey and red to orange. If the motor runs it's the decoder and its wiring. If not it's between the pickups and socket. Use a multimeter to check that current is coming through when you connect red and black though the sockets. If you can remove the socket  from the chassis check that there is a connection between the wires at the socket tubes. (I have had this problem several times, usually a cold solder joint that has got insulated with oil from the wheels/gears). I normally do all of this on the DC test track.

3. Check that the wires to the decoder are in place. If the decoder has a wired 8 pin plug check that the wires are firmly attached the pins. Slight pull on each one will identify a loose one. (I have also had this happen several times). Also check at the decoder for loose connections. If you wired directly check for cold joints.

4. Worn insulation on any of the wires resulting in a short will also stop it from running. 

5. Loose and live ends on wires coming from the decoder (direct or though the plug/socket) meant for lighting will also stop it running if they contact the chassis or another wire. Form a U at the end and seal using transparent heat shrink.

Check the connection between the pickups and wiring going to the plug. Both bogies and where the wiring from each gets joined.

Nigel


Edit: Yes, remove the decoder and it will run on DC if the wiring is good. If you hard wired it wire back to the factory original, if it already had a decoder plug replace with the DC board. If you can't find it you can use a couple of bits of insulated wire across the black/grey and red/orange sockets. The DC board doesn't blank, it cross links the pickups to the motor.

You didn't say whether it was hard wired or not. If this is an old Bachmann "DCC ready" model the pickups and wiring is where I would start. Age does not treat them  kindly. You could have been running on one bogie, which has now failed.

One argument for not hard wiring is that If a decoder is suspect it can be quickly swapped for one that is known to work or put in a locomotive that runs with DCC.

[user=753]Phil.c[/user] wrote:

…, power straight to the motor works,….

Phil,

Do not connect power direct to the motor if the decoder is still connected/plugged in as it will damage the decoder.

Best regards,

Paul

Wot 'e sed. I think. Decoders put out PWM DC to the motor, Feeding PWM DC into the orange and grey wires via the motor terminals when this is the normal state of affairs? That said, a lot of electronics in the decoder is one way.

I always remove the decoder when testing after checking it through the program mode. So it's never happened.Not about to experiment either.

Nigel