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Stuttering DMU

Posted: Mon May 03, 2021 2:42 pm
by Nine Elms
Looking for some help.

I have a Bachmann 108 DMU that is causing some concern. It runs OK on the straight but as soon as it enters a curve (No 2 radius) it stutters. I have a Hornby Select controller and when I set the speed knob to zero the DMU continues on its merry way, at the same speed, and finally stops after a couple of laps of the track!!! Another problem is that one of the carriages' internal lights do not work.

For clarification: I have cleaned the track and my 4-6-2 loco runs perfectly well and will stop when controlled to do so. All track has droppers connected to a bus wire as per Brian Lambert.

Any help gratefully received, thank you.


Re: Stuttering DMU

Posted: Mon May 03, 2021 2:46 pm
by Walkingthedog
Have you cleaned the wheels and pickups?

Re: Stuttering DMU

Posted: Mon May 03, 2021 4:03 pm
by Brian

Running on uncontrollably is caused by the decoder losing its digital signal and seeing the rail volts as full DC volts.
Do as WTD has suggested and clean all rails and wheels treads first, then if the problem still exists you will need to turn Off DC operation on the decoder by CV29. Reducing whatever value is in CV29 by 4. e.g. If 6 make CV29 value 2.
Your Select will have to be at the latest firmware version of either 1.6 or 2.0 to allow CVs to be set. If upon initial start up the very first digits are displayed as 16 or 20 then all is good.
If it shows less than these e.g. 14 or 15 etc then I would highly recommend having it upgraded to the latest firmware, but this can only be carried out by Hornby. So a call to them to obtain a returns number and then post it back will give you an enhanced Select. Note there is a small fee payable of £15 plus VAT You pay P & P to Hornby and the return P & P is included in their charge. But if it needs upgrading do not just send it back, you must obtain a return/repair authorisation number. Hornby contact details are here ... 99-Repairs

Re: Stuttering DMU

Posted: Mon May 03, 2021 8:22 pm
by RAF96
I have the B’mann 108 pair fitted with a pair of Lenz golds and it runs superbly. A bit over the top but they were lying around looking for a home.

Edit - the cabin lights are extremely dim.