Heljan AC Car Railbus - wierd behaviour with Lenz 21 pin Decoder

[Gdaysydney]

This afternoon I finally got around to putting a decoder into a Heljan AC cars Railbus  ( model 88031.)

 

One of the reasons for not being in a rush ( I have had the model for a number of months) was the warnings about taking care with the body removal which turned out not to be as tricky as I thought.

Having tested the loco and run it in on DC I removed the body and attached a Lenz Silver 21 pin decoder - programmed the decoder and then  tested the loco  again at low speed to check everything was working before reassembling.

 

Everything going well - but then,  when I increased the acceration to step 14,  the railcar stopped - lights went off - nothing.  Took the loco off the track and then replaced it - this time running it in the other direction - again  it spluttered at around step 17 before doing doing the same thing - i.e nothing !.

 

I tried a different Lenz silver decoder and got  the same result.  I inserted one of  the decoders into a Bachmann class 37  and the loco ran like a dream so its not a faulty  decoder(s).

 

I'm thinking that maybe the motor in the Railbus is drawing too much current and that is triggering the behaviour I am observing although the Silver specs say it can handle 1.1amps 

 

Any ideas ?

 

Apology for the spelling - weird -

[resin001]

I had exactly the same issue - ended up with a Bachmann decoder which works ok , although the Lenz would have been the preferred option as I could have dimmed the headlights as they are too bright !

 

I do not know why this occurs with the Lenz decoder - it works perfectly in other loco's

[amdaley]

It sounds like the motor is drawing to much current.

Perhaps an extended running in period on DC might help.

[RFS]

Put it on the programming track after this failure and check the contents of CV 30.  If there's been an overload or short circuit then CV 30 will be updated to say what the issue is.

[Bilbo]

I had a problem similar to this with the W&M railbus.I came to the conclusion that as Heljan motors are notorious for their current draw that was the cause  of this problem.However I had originally used a Bachmann 21 pin but found the TCS 21 pin EU version solved the problem and had no problem then when I used a TCS in my AC Railbus as well.

[Captain Kernow]

Interesting - I didn't even realise these railcars were out!

[Gdaysydney]

Thank you for your suggestions and stories of similar experiences -

 

I have a Bachmann 21 pin in another loco so for the time being I'll switch them around after I have experimented some more

 

I have been doing some reading overnight and my suspicion is that it may be the EMF that is creating the problem .  I will follow RFS's advice and check out. 

 CV30 to see what is shows after the Railbus grinds to a halt.

The manual also says the performance of the decoder can be optimised to one of 6 specific motor types in the locomotive using CV50, which is also the CV controlling EMF.  Now I just have to find detials of the 6 specific motor types and then whether the Heljan motor fits any of them. ( Given Heljan's pedigree I would assume that one of them would be right given Lenz is also from Europe )