Blue rapier dcc running problem

[Darthtrainspotter]

Hi. I recently bought a blue rapier railroad version train second hand  and converted it to dcc. Since all the wiring was black and I wasn’t too fussed about lighting as I wanted a quick fix I ripped out all the PCB leaving just the front and rear pick ups and the left right motor feeds. I hooked this up to a Bachmann chip. 

i Have an elite controller so no issues with compatability using a Bachmann chip. 

Thing is it runs but in a sort of on off fashion. ive tried changing ac and de but no matter what I do it just jumps out of the blocks races round and comes to a crunching stop not a nice rolling stop. 

Ive converted lots of loco and had to chop out the capacitor between motor terminals and was wondering if that was the issue. But I can’t see one 

any ideas 

[2e0dtoeric]

First question - did it run well BEFORE you modified it?

'ive tried changing ac and de' - -What are they?

'jumps out of the blocks races round and comes to a crunching stop' - - typical indicator that the motor is seeing 16v, and not the controlled output of the decoder, so either you've got a wire wrong, or the track, wheels, and/or pick-ups are filthy!

[Darthtrainspotter]

First question - did it run well BEFORE you modified it?

'ive tried changing ac and de' - -What are they?

'jumps out of the blocks races round and comes to a crunching stop' - - typical indicator that the motor is seeing 16v, and not the controlled output of the decoder, so either you've got a wire wrong, or the track, wheels, and/or pick-ups are filthy!

Ac acceleration de decelerations

ill put another decoder in and see what happens as for running well before no idea I only have dcc controller 

[walkingthedog]

You should never convert a DC loco to DCC unless it runs faultlessly on DC. 

[96RAF]

You could have used my guide for conversion...

http://www.halton96th.org.uk/article9.html

Rob

[Darthtrainspotter]

You should never convert a DC loco to DCC unless it runs faultlessly on DC. 

Like I say I don’t have dc controller so couldn’t check 

[Fishmanoz]

Doesn’t seem like DC Runaway as Eric suggests because it stops again.  Particularly as it jumps off then stops abruptly, sounds more like a mechanical thing stopping it until motor volts is quite high, then stops again as soon as motor volts starts to drop.  Does it take a little while before it starts, then stop immediately?

 

I would start by giving the motor and bogie a good service. 

[Darthtrainspotter]

It seems to take off and stop fairly quickly. I’ve been over it with a fine tooth comb the motor bogie and pick ups all look pretty clean and new. I’m gonna have to strip down I think and as you say look for a mechanical issue. I’ll swap the chip out too just in case it was a dUff one 

cheers

[96RAF]

When you get this type of periodic stop/start behaviour in DCC it usually means the decoder is self protecting against overload. Run it with the body off and when it stops feel the decoder for heat. It will be warm but should not get overly hot. Have you got it wrapped in tape. A picture of the installation could help while you have the top off.

Rob