LW Won't Work Under Load

745 views
5 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January, 2006
  • 182 posts
LW Won't Work Under Load
Posted by gottcent on Wednesday, April 11, 2018 3:57 PM

My postwar LW transformer was working fine until recently, but it has now decided it will not work under load. If I connect a voltmeter across terminals U and A and slowly move the voltage control arm, I get the proper readings. But as soon as those terminals are connected to a load (either a small 520 engine or an operating accessory) the voltage drops to zero. (The constant voltage terminals do not seem to be affected.) I checked the circuit breaker and its contacts are closed. Any thoughts?

  • Member since
    December, 2001
  • From: Austin, TX
  • 9,775 posts
Posted by lionelsoni on Wednesday, April 11, 2018 7:16 PM

Does the lamp light up?

 

Bob Nelson

  • Member since
    November, 2012
  • 655 posts
Posted by emdmike on Wednesday, April 11, 2018 7:20 PM

Sounds like a solder joint has gone "cold" and will conduct but not under a load, kind of like a loose battery cable on your car, will work till you try to crank the starter, which is a huge amp load.  Probably something simple.  If diving into the internals is beyond you means, leave it to someone that works on these.    Mike the Aspie

 

Silly NT's, I have Asperger's Syndrome

  • Member since
    December, 2005
  • From: Hopewell, NY
  • 2,769 posts
Posted by ADCX Rob on Wednesday, April 11, 2018 7:44 PM

gottcent
...I checked the circuit breaker and its contacts are closed...

I was not aware you could see the contacts on the LW transformer circuit breaker.

The syptoms point to the breaker. Try actually running a jumper to bypass the breaker and check again.

Rob

  • Member since
    January, 2006
  • 182 posts
Posted by gottcent on Thursday, April 12, 2018 8:45 AM

Thanks for your replies. Yes, the lamp lights up. I will follow up on your tips by searching for a loose connection and bypassing the breaker.

  • Member since
    December, 2001
  • From: Austin, TX
  • 9,775 posts
Posted by lionelsoni on Thursday, April 12, 2018 9:59 AM

The circuit breaker is in series with the AB and AC accessory circuits and also the pilot lamp.  That seems to rule out the circuit breaker as the culprit and to point to the whistle-and-direction circuits as the location of a high-resistance connection.

Bob Nelson

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

FREE EMAIL NEWSLETTER

Get the Classic Toy Trains newsletter delivered to your inbox twice a month