Bachmann 2EPB Surging

[kevinlms]

A friend of mine has a new 2EPB and when running down even a gentle incline at low speeds (1 in 50) it noticeably surges, but runs perfectly on the level or uphill. Doesn't matter if power bogie at top or bottom.

Its currently got a TCS decoder in it (model number unknown at present), but apparently it was the same on DC with the blanking plate in - so nothing to do with DCC.

 

A search reveals 2 possible solutions, 1/ use a Bachmann 21 pin decoder or 2/ Add foam between 1 or more axles and the floor to create friction and dampen.

 

Since these cures were from approx 12 months ago, does anyone have further suggestions before these methods get tried. Probably the foam one will be tried first as zero cost.

 

TIA

[HLT 0109]

Kevin,

 

As you say it is new, I would recommend a query with the supplier before trying any modifications. It may be faulty in some way. Even though the problem was evident in DC (and therefore not caused by DCC) it is possible that a change to one or more CVs may help - possibly those affecting the back EMF. I am not proficient in this area but others may be able to offer some guidanc.

 

Harold

[RFS]

Back EMF on DCC is supposed to compensate for this but is sounds like it's not working correctly on the TCS decoder you have fitted. Of course the same thing will happen on DC because that doesn't have Back EMF either.  You could try a different decoder but I've had a lot of problems with mine and I've got 4 units now.  My preferred decoder is the Lenz Silver21, as fitted to my 4CEPs, all of which run impeccably.  But the 2EPB has various problems with this decoder, including erractic starting and stopping.  Others have reported similar problems and I've seen one report of this with a TCS decoder too. 

 

Two of mine now have the Bachmann 21-pin decoder and they run fine, but this is a basic decoder which does not support advanced consisting.  Fortunately I'm using RR&Co automation and that handles consisting without the need for decoder facilities. I have another fitted with a Hornby Sapphire decoder now and that's OK as well. I run that in consist with the Lenz-fitted one which keeps it in check!

 

I had a lot of problems with TCS decoders and eventually replaced them all with Lenz.  You could search this forum for the threads that have been raised to discuss this.

[34theletterbetweenB&D]

Relating to the 'starting and stopping' with the Lenz Silver. Now I

(a.) don't have this model

(b.) but do have the class 105 of not wildly dissimilar construction, and,

(c.) have great confidence in the current Lenz decoder line.

 

There's nothing to beat all soldered connections wherever possible from pick up to decoder. Bach have gone for wiping contacts in the circuit of their MU's rather than all soldered on wire connections. That's where I would be looking, the irreducibly necessary moving connections between rail and pick up are quite enough in the circuit. It is possible to change CV112 to alter the timeout that the decoder applies after a track power loss. If that changes the decoder performance in this respect, you then know that there are lapses in track power reaching the decoder which need to be fixed.

[RFS]

Relating to the 'starting and stopping' with the Lenz Silver. Now I

(a.) don't have this model

(b.) but do have the class 105 of not wildly dissimilar construction, and,

(c.) have great confidence in the current Lenz decoder line.

 

There's nothing to beat all soldered connections wherever possible from pick up to decoder. Bach have gone for wiping contacts in the circuit of their MU's rather than all soldered on wire connections. That's where I would be looking, the irreducibly necessary moving connections between rail and pick up are quite enough in the circuit. It is possible to change CV112 to alter the timeout that the decoder applies after a track power loss. If that changes the decoder performance in this respect, you then know that there are lapses in track power reaching the decoder which need to be fixed.

Thanks - but it's definitely a "characteristic" of the decoder which I believe is caused by interference with the lighting circuitry in the 2EPB, as others have found. (Erratic performance varies depending on whether the interior lights are on or off).The pickups are the same as the Bachmann 4CEPs and these don't have the same problem.

[34theletterbetweenB&D]

Interesting. At a guess, the erratic behaviour occurs with the interior lights on? If so, I would be concerned enough to want to test that the problematic lighting circuit is fully isolated from track supply.

[Sam Moss]

I've got a 4CEP, 2 EPB, a Class 108, a 105 and a Derby Lightweight and they all do this down hill. I think it was mentioned on the old forum about it being the gear box running away down the hill, then the motor catches up and so on. it can be solved by inserting a thin piece of plasticard as a acking piece against one of the gears in the bogie tower. Just thick enough to stop the gears being sloppy and really easy to turn.