Or not running your trains..

Discussion in 'Running Your Trains' started by Andy_Sollis, Sep 5, 2019.

  1. Andy_Sollis

    Andy_Sollis Full Member

    Messages:
    1,123
    Likes Received:
    1,029
    Joined:
    Aug 4, 2018
    I have had an old Mainline Class 56 for 20 odd years, that around 17 years ago was converted to DCC and fitted with express models lighting. It’s got a Lenz decoder in it.... it never was the best of runners, so has been sidelined for a number of years.

    Came to check it today and ..... nothing...

    Loco responds with its functions, but the motor shows 0.2v on the motor terminals when at full power.

    Any thoughts of the decoder may have failed? Or if the motor lost magnetism ?


    I guess folk will say only way to know is to remove the chip and try it on DC and see what happens?

    (No, I’ve not yet stuck it on decoder pro to see what it reads)

    Andy
     
  2. SMR CHRIS

    SMR CHRIS Staff Member Moderator

    Messages:
    3,230
    Likes Received:
    444
    Joined:
    Dec 31, 2015
    Hi Andy
    Some of the light duty ring field motors like in the Mainline range or the later Hornby ones don’t always respond very well to DCC conversions I’ve found on occasion they can react as if open ie there’s is so little resistance at certain points in the cycle, and some decoder’s then won’t activate the motor circuit, as it sees no complete motor circuit, To reference BEMF
    Turning the motor slightly will usually get it to a position that makes a full circuit and it may come back to life until it finds that spot again.
    I know it’s the norm and recommend to remove all Capacitor’s when doing DCC installs but I have found with these affected ring field motors a very small Cap can overcome this issue as it is just enough to have the decoder recognise as a completed circuit all the time.

    If it’s not the above, you may have had a failure of the decoder or the brushes in the motor may not be contacting or have broken down over time or the motor has a open segment.

    Eliminating one item at a time will be the go
    Let us know what you find.
     
    Andy_Sollis likes this.
  3. Andy_Sollis

    Andy_Sollis Full Member

    Messages:
    1,123
    Likes Received:
    1,029
    Joined:
    Aug 4, 2018
    I never thought about the back EMF... however turning the motor doesn’t start it. I had all the motor apart and cleaned the commutator and the brushes (as they looked black from old oil.) and they were shiney, so unless it’s the decoder, I can only think the magnet has lost its pull due to its age.

    I’ll get the soldering iron on it and bang it on DC and see what occurs.
     
    malc60015 and SMR CHRIS like this.
  4. Andy_Sollis

    Andy_Sollis Full Member

    Messages:
    1,123
    Likes Received:
    1,029
    Joined:
    Aug 4, 2018
    Nope not back EMF. Had it on decoder pro. Very odd as can hear the click of the motor each time is acks a cv update, yet nothing upon using the throttle. Lights work perfect.
     

Share This Page