DCC Loco weight problem?

[robcat]

Hi all.

Sorry, I posted this under General Discussion by mistake so here it is in the correct area(I think!)

My recent posts concerned bad running with Hornby factory fitted DCC locos when used on my new NCE controller. Running is fine on Hornby Select but the locos don't like the NCE. I thought it was down to older Hornby decoders and replies to my post suggested that but having looked at them they have all a blue spot on the largest component, from forum discussions this suggests they are the newer R8249 and not the older R8215. All other possible reasons for bad running have been checked out and now I have finally discovered that if I rest a weight on top of the locos they respond to the controller, remove the weight and loco stops. Most of these these are all small 0 6 0 locos (08, Jinty, Pannier Tank) so are light but  there is a Castle Class with the same problem and all originally came from Hornby Digital GWR Pullman and Mixed Goods sets I bought to start off my layout as a cheap way of getting rolling stock  and track.(2009)

It seems strange that weight is the possible answer when using NCE control.

I have fitted an R8249 to my new Hornby Prairie 61xx DCC ready loco bought seperately last year and it works perfectly on NCE control. This is a heavier loco.but so is my Castle from the original sets and that has problems.

Voltage change from 15.1VAC Hornby Select to 14VAC NCE(NMRA standard) measured at the track is another variation but I am not sure whether that would make a lot of difference as the R8249 is NMRA compliant.

Should I add some weight?. This may cause problems by overloading the running gear and overworking the motor.  Weight of around 400grams is needed which is more than the original loco weighs. It doesn't seem right somehow.

I was going to buy lots of new decoders but now I am not sure if that is needed

Totally lost and going round in circles. Can anyone help please?

[81F]

 Hi Robcat,

Firstly I'm no DCC expert but I wonder if it is a contact issue and only have one factory fitted loco. However, all my Standard Horby 0-6-0 chassis were hard wired by myself, if found that some have been difficult to program unless I applied some pressure to them but this was with an elite. However, these tended to be the older 0-6-0 chassis with sprung back wheels.

 

Interestingly my first 27XX panneirs (one of the originals with X03 type motor) had a lenth of metal rod in the bunker to add weight which is absent in some of the newer ones. Putting a similar sized bit of metal in the empty bunkers (acessed by removing the coal) did help some, so it might be a case of where to add weight.

 

However, if there is no problem when the the Select is used it all seems baffling. Hopefully someone else will be able to offer more help but I hope my comments on missing bunker weights help. 

[robcat]

Thanks 81F.

Weight seems to improve running and stability but I feel there is more to it than that. Possibly the lower voltage at the track means the contact is indeed  not sufficient as you suggest and extra weight gives an improved surface pressure on the wheel / track . Alternatively the lower voltage may mean the decoder is not picking up instructions properly. Unfortunately with the Hornby R8249 the Start, Mid and Max VoltageCV's cannot be accessed so I cannot give the motor a kick start. Perhaps I should take a chance and buy a different, more programmable decoder( possibly Zen) and hardwire it, an added advantage is they come with a stayalive so that is a bonus. As I said before the booster is adjustable via an internal potentiometer to get near the 15VAC but it means running the supply at the top limit of recommendation and it only improves things slightly. That puts the whole system above NMRA standards of 14VAC which is not good.

I will try some weight and see what happens. 

The factory fitted decoder is hardwired to an extent but has a 4 pin flat plug/socket (similar to a JST connector)near the motor where the decoder wiring connects. Maybe I can buy a harness with a flat socket to go from that to a standard 8 pin rectangular socket then I can plug in different decoders

[Howbi]

It's very easy to question the electronics but priority should be given to the basic requirement, clean track, clean wheels and clean pick-ups............if better contact is made by pressing down on the loco it would indicate that some grime is interfering with good electrical contact so may I suggest a thorough cleaning regime...... 😀.....HB

[robcat]

Thank you  howbitman, a good point.

I have made sure that the track and wheels are very clean, these locos are in good condition, fairly new, and have not been used a lot except for a few hours running in. If the problem is dirt then why do they run well and are controllable when using the Hornby Select from new but don't respond well to the NCE? Again, the new heavier Prairie loco is fine so I doubt track grime is responsible. That is one reason why I thought about voltages.

Any more help please? This problem is becoming tedious - but all things are solvable with the right approach

[robcat]

Further info on my problem.

I have found out that I have  factory fitted X9659 decoders in the small locos. These are non compliant NMRA according to Hornby. I might try R8249 as replacement.

Is there a harness available with one end 4 pin flat socket to match the plug in the loco and the other end a standard 8 pin rectangular socket so I can plug the R8249 in? This would save re hardwiring everything.

[96RAF]

I dont know of an 8-4 pin adaptor, but if you can solder and the old decoders are going in the bin then just cut of the plugs from both old and new decoders leaving a bit of wire to work with and splice the 4 pin plug onto the 8pin decoder wires, else you will have to hard wire it in.