Lionel LW Transformer Rectifier Upgrade

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  • Member since
    December 2023
  • 1 posts
Lionel LW Transformer Rectifier Upgrade
Posted by TCLionel on Monday, December 25, 2023 1:11 PM

I recently purchased a Lionel LW transformer with the original rectifier disk.  I would like to replace the disk with a stud mounted diode.  Plan is to use the transformer with both pre/post war & modern era locomotives relative to the operation of a whistle &/or horn.  My understanding is that the polarity of the diode is not an issue with a pre or post war locomotive but is with a modern era engine.  I have come across the following diodes, Lionel 1041-13X NTE5870 and a diode numbered 1N1190AR as two possible options.  Will either of these work or is there a better alternative?  Appreciate the assistance.

  • Member since
    March 2010
  • 266 posts
Posted by rrlineman on Thursday, December 28, 2023 1:38 PM

for years now I have used 6-10 amp diodes. The original discs were only good for 5 amps. As you noted, pre & postwar dosen't care what polarity it is as long as it works. Yes the modern electronic are polarity sensitive. That is why Lionel came up with the 2 "railsounds" button set-up to make the sounds work with postwar transformers. The newer trainsformers had this built in using electronics.


The easiest way to replace the diode is do what I have found works on ZW's. Use a #12 yellow ring crimp terminal, remove the insulation. Split the wire tube open to accept the screw end of the stud. Crimp it tight around the threads and the solder the end where the threads of the stud faces the ring hole of the terminal. after that use 1 of the screws that hold the light bracket/whistle switch as your ground point. then unsolder the wire to the disc retaining clip and solder that to the diode terminal end. It should now be ready for service.


On your LW you might not be able to do it this way.  you may have to drill and thread a hole on the bracket of the disc and then solder a wire from the diode terminal post to the copper strap that holds the pin for the old disc.  hope you get what I'm saying and this helps. ( the 2nd option also applies to the 1033/44 transformers) Don't consider the cheapo epoxy diodes. I have replaced several that others have done and have blown or melted apart.

  • Member since
    December 2005
  • From: Hopewell, NY
  • 3,212 posts
Posted by ADCX Rob on Thursday, December 28, 2023 5:15 PM

Yes the modern electronic are polarity sensitive. That is why Lionel came up with the 2 "railsounds" button set-up to make the sounds work with postwar transformers.

All whistles & horns made since 1972 are polarity sensitive out of necessity as all whistle controllers/transformers since 1935 put the positive offset to the center rail when connected properly.  The bell feature came much later, but fell into this scheme perfectly.

A problem arises however as most of the Lionel schematics show the wrong installed polarity in the diagrams... but it didn't matter until 1972, so check your whistle/horn and bell operation before buttoning up your transformer.


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