Model Railway Forum

I have a Bachmann cl.80 tank loco, DCC fitted, which will not run at much more than crawling speed. The speed does not change beyond about about step 11 on my NCE Powercab. This has previously been one of my best running locos and the wheels & contacts all seem clean. I have tried swapping decoders but it makes no difference. Could this be a motor problem? Any suggestions welcome!

Are you able to put a blanking plate in and test it on DC? This should help to determine whether the problem is the motor or the decoder, although swapping decoders may already have given some clue (but running on DC will give more confidence).

Hi
Before removing the decoder I would carry out a decoder reset CV8 enter a value of 8. This should reset all CVs to their default values and the address to 03.
Once that has been carried out and if it doesn't cure the slow running, I would then check a couple of CV values.... CV 5 Top speed and CV3 acceleration rate, setting them all to their minimum values initially usually 1 or 0 depending on decoder manufacturer.

I have already tried resetting the decoder more than once, to no avail. Running in DC is not an option as I no longer have a DC controller.
Will have another go at changing those CV values though. I think I set CV5 at the maximum 255 instead of the minimum?

GrahamU wrote: ↑Tue Apr 26, 2022 7:45 pm I have already tried resetting the decoder more than once, to no avail. Running in DC is not an option as I no longer have a DC controller.
Will have another go at changing those CV values though. I think I set CV5 at the maximum 255 instead of the minimum?

If you do not have a DC controller, you can run on DC by using a 9v battery: just take a spare piece of track, not connected to a DCC controller, and touch the battery terminals on the rails.

Well I finally purchased a new 9V battery and tested this loco in DC. It still runs only very slowly so clearly there is no problem with the decoder which really suggests the motor is the issue. I would have thought that a motor either works or it doesn't. Any suggestions about what might cause this problem with a DC motor?
Should I contact Bachmann perhaps?

Hi
A word of caution... Whatever you do, DO NOT connect a DC power source (battery or a DC controller) directly to the motor terminals with the decoder still connected. Failure to disconnect the decoder from the motor and applying a DC voltage directly to the motor, will usually result in total and terminal decoder failure!

Do you have the locos DC operation Blanking Plug? If so, remove the decoder and insert the blanking plug and retest on a suitable DC power source.
Note: A 9volt PP3 type battery will turn over a locos motor, but will probably not provide sufficient voltage to allow the motor to run at its top speed. Most DC train controllers output around 13.5 to 14.5 volts at maximum speed setting and some even more! If possible, test on a DC train controller of some sorts to ensure maximum volts are present.

If all this still fails to produce a decent top speed then contact Bachmann.

Dont worry I did use a blanking plug!
It stands to reason that 9 volts will not generate the top speed. I find that one of the minor frustrations of running DCC is that one still seems to require a DC control system to diagnose issues like this one! Not something that is commonly discussed...

Sounds like a new motor required to me. I have had this problem myself. Pity these can motors are not servicable. It is probably deposits built up on the comutator. In the old days quick clean and all was well.