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Discussion Starter · #1 ·
I have a new Bachmann 8750 class Pannier tank fitted with a TCS MC2 chip.
I use a Lenz LH100 controller set to 28 steps.
At default CVs it does 0 - 60 on step 1 and goes in to orbit shortly thereafter.

After reading other threads and playing around with CVs 2/3/4/5/6, the following settings have slowed it down a little but it is still far too fast.

CV2 - 0
CV3 - 0
CV4 - 0
CV5 - 100
CV6 - 30

Can anyone suggest ways of obtaining a more sedate pace befitting its role in the goods yard?

Thanks
Pete
 

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In depth idiot
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I have a half dozen Bachmann six-coupled tank chassis all with similar motors and gearing, from the pannier, 56XX and Jinty, all are very similar with a top speed around scale 60mph, and good control through a well graduated speed range, pretty much on default settings with Lenz silver or gold or Zimo MX63 decoders.

I rather suspect that you have a duff decoder; first thing I would try is a factory reset to see if that restores something corrupted. If that doesn't help try exchanging it with one in another loco that has good slow speed control, and if the problem travels with the decoder, then you know the decoder is not right.
 

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Have you removed the capacitor(s)?

Is this a TCS decoder with BEMF?

You'll also find that you can get much more precise control with 128 speed steps.

Regards

John R
Bromsgrove Models
 

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Hi Pete

Welcome to the Forum

With Bachmann motors there is a capacitor across the motor circuit that drastically Affects the speed curve when using a Quiet Drive decoder. It causes an over-speed problem. It must be removed from the circuit.

There are more details on the TCS website Here

Hope this helps

Regards

Zmil
 

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Definitely check for, and remove, any capacitors.

Also, try changing the settings

CV5 - 50
CV6 - 28

These will lower the top speed and give a shallower acceleration curve at the lower end.

After that you could add inertia settings to CVs 3 and 4 as these will smooth over any steps in the control. As an aside, I prefer to run all but one of my locomotives on 28 steps but with fairly high settings in CVs 3 and 4. Only that one odd one works much better on 128 steps.

It may take a while experimenting with the settings until you are happy - leave CV3 and CV4 set at 0 until you are happy with the top speed and speed steps, then try altering them.
 

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QUOTE (SRman @ 2 Dec 2008, 16:29) <{POST_SNAPBACK}>Definitely check for, and remove, any capacitors.

Also, try changing the settings

CV5 - 50
CV6 - 28

These will lower the top speed and give a shallower acceleration curve at the lower end.

*** Careful: Not all decoders are the same. ESU has CV5/6 with a range 0 to 64, Most other brands are 0~255.

With 28 speed steps, your controller is simply choosing to jump 4 steps at a time - the decoder is actually always at 128... Adding higher settings to CV3/4 then smooths the jumps, so the ONLY real difference is the distance the knob has to be turned (128 requres more steps, so needs more rotation to full.

Richard
 

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Discussion Starter · #7 ·
Thanks for the suggestions.
I am now a happy but bemused bunny.
I'm happy because the problem is solved but bemused because I don't understand how!

I took the advice from 34C.
I did a factory reset which created the original starting point i.e. 0 - 60 on step 1.

Then I removed the decoder from the Bachmann and put it in a Hornby Pannier which normally has brilliant speed control - and it still had! Clearly not a decoder problem.

I put the decoder which worked so well in the Hornby in to the Bachmann and got great speed control.

Just to be sure I put the original decoder back in the Bachmann and got 0 - 60 on step 1!
I have switched the decoders around again and now have 2 panniers with great speed control.

I don't understand the physics but now it ain't broke so it don't need fixing.

Thanks again for all your input

Regards
Pete
 

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Hi Pete

Glad you have it sorted

TCS are quite specific regarding the Bachmann Loco's - the Capacitor must be removed or you get out of control speed

The decoder you ended up putting in the Bachmann is probable not as sensitive to capacitors charging and discharging across the motor circuit

Regards Zmil
 

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Going on from this thread a little, I recently purchased the bachman G2 with decoder already instaled, and after going through the running in process, i find that the loco jerks at low speeds, it will not run smoothly, i removed the boiler and applied a few drops of oil in the required places, with no results, but i did notice that there are 2 capacitors fitted? have these been fitted by law? are these causing the jerky movements at slow speed? should i remove them? any comments gratfully recieved.
 

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Hi Thunder

Capacitors are across the motor circuit to suppress Interference on TV and radio frequencies

Most decoders have there own suppression circuits built in and do not require any external capacitors
and the external capacitors play havoc with the BEMF causing irregular running

If your track , wheels and pickups are clean your loco should be running smoothly

Remove the Capacitors and you will get improvement.

Regards Zmil
 

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QUOTE (Thunder @ 4 Dec 2008, 01:43) <{POST_SNAPBACK}>Going on from this thread a little, I recently purchased the bachman G2 with decoder already instaled, and after going through the running in process, i find that the loco jerks at low speeds, it will not run smoothly, i removed the boiler and applied a few drops of oil in the required places, with no results, but i did notice that there are 2 capacitors fitted? have these been fitted by law? are these causing the jerky movements at slow speed? should i remove them? any comments gratfully recieved.


***There are no "Legal" implications from any owner removing the capacitors when installing a decoder. The capacitors are part of a suppression circuit is as Zmil mentioned, but it is only valid under DC running. (as soon as a decoder is added to a DC loco the loco electrical circuit is changed so the overall suppression pattern / capacitors effectiveness changes anyway)

Capacitors can be removed easily with cutters or soldering Iron.

Decoder circuitry has more effect on suppression than was originally in place via the capacitors so they are no longer valid and it will NOT create a problem for interference by removing them, however running quality will be improved.

regards

Richard
 

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Thanks for your reply Richard & Zmil, I thought that was the case, so I wonder why they have been left in place, as the loco was purchased new with the decoder fitted, why have Bachman left the capacitors in place when fitting the decoder, seems strange to have to remove them ours selves to get smoother running ?
 
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