Problem With Stem Diode Upgrade On PW ZW

[MickeyDemian]

Hello All:

  Just finished installing 2 stem diodes (bought on ebay) on a PW  ZW.  I have performed this task 3 times before with no problems.  Today when I tested the transformer and activated the whistle switch the full distance I could push it, the engine not only whistled but also stopped ( and kept whistling while stopped).  When I push the switch a small distance, say  1/2 inch , only the whistle engages.  So a full push of the switch stops the train and whistles while a partial push of the the switch only activates the whistle.  All other functions are normal-stop button, power etc.   Both sides A  and D  whistle switches perform this way.  Are my contacts fried, did I hook something up wrong?  Any experience or insight on how to fix this would be appreciated.

                                                         Thank You:   Mickey

[gunrunnerjohn]

Sounds like you didn't get the resistance wire that parallels the diode with the switch full over connected properly.

See if you get all DC with the switch full over, you should have a few volts DC, but plenty of AC when measured.

[lionelsoni]

What's a "stem diode"?

[TrainLarry]

  My guess is that "stem diode" could either mean an axial lead plastic-cased diode, or a metal "stud" diode that is threaded on the stud end.

Larry

[azflyer]

This link may help you from my web site Classic American Flyer Cabinet-top Train Layout. I run the ZW transformer with updated diodes on my layout, which is American Flyer with Railsounds. No problems.....

This is the link: http://www.tranz4mr.com/site/ZW_Whistle_Diodes.html

AZ-Flyer

[Rescuedtrains]

AZ-Flyer,

Thanks for the link. It will  help when I install diodes in my ZW.

 

Steve

[webenda]

lionelsoni

What's a "stem diode"?

.

.

Just a guess as to what Mickey means by stem diode... From USP4176242:

[Lionelking313]

Guys, these are the diodes I have been using for a long time now, and never have failed me yet!!! Give them a try, dont buy those ones on ebay.

http://www.allelectronics.com/make-a-store/item/1N1190AR/40-AMP-600-VOLT-RECTIFIER/-/1.html

 

Mark

 

[MickeyDemian]

Well,  I  found the answer to my problem was simple and once again caused by my own stupidity.  In examining all of my solder connections  I determined that the problem was the over travel of the switch when whistling was activated,  since I was doing this testing without the main top cap placed on the unit.  I do this to observe for smoke or sparks sometimes.  I failed to mention in my original post that I was testing the unit without the top on, and I apologize.  Therefore, the top cap, once installed,  has stops molded into it that prevent the over travel of the switch that initiated the problem I was describing above, stopping the train while whistling at the same time.  I suspect the switch makes contact with another contact point that initiates this problem during the over travel.   As a relative novice to repair of Lionel, I always tend to learn something new with every project---I guess thats called experience. 

   Thanks to all for the timely and informative replies, I appreciate it.

                                                                         Mickey Demain

[Lionelking313]

 

This is what you should be using.

 

Mark

[TrainLarry]

Glad you found the problem. Actually the overtravel of the whistle switch caused it to break contact with the transformer windings, thus stopping the train.

Larry

[gunrunnerjohn]

Like I said before, what happened is you lost that resistor that was in parallel with the diode, so all you had was DC.  Makes perfect sense now that you tell us that. :)