Williams SD-90

[Trainman702]

I recently bought a new Williams SD-90 BNSF Powered engine at a local train show.  When I first ran the engine on my layout (have Lionel Fastrak), it hesitates/jerks everytime it goes over a switch and the cab lights blink on and off.  I have another Williams SD-90 (BN) and it does not do this.  Any ideas why this is happening?  It is very frustrating.

[Joe Satnik]

Dear TM,

Your SD-90 has two middle rail roller pickups for power, one under each of the trucks.   One of them is not working properly.

1.) Turn your loco upside down in a foam cradle (to protect the finish).  Check to see that both roller arms (and their roller axels) are well centered, not hung up and have equal "springiness".  Check to see that both rollers roll smoothly and freely, and have no flat spots or grooves worn into them.

2.) Use the two track power wires from your power pack to power your upside down loco. 
Set the power pack to a low speed.   
Touch the end of one wire to a wheel, and the other wire to a roller pickup.  The reverse unit should respond, cycling the loco through its forward-neutral-reverse-neutral pattern.  Do the same test with the other pickup. 

Report back your findings.  (More tests/repair suggestions to come.)

Sincerely,

Joe Satnik

[Trainman702]

Thanks Joe for your help.  I tried everything you said and all is fine with the rollers. etc.  The engine is still hesitating through the switches and the lights still flash.  Any other ideas or helpful hints?

Harry Hiss

[3rail]

Dear Harry,

Try running your locomotive for 15 minutes or so at a rate of speed fast enough so that is does not stall on the switches.  Immediately take it off of the track and touch each of the rollers.  If one of the is not connected it will be cooler to touch than the other one.  If this is the case the wire is either bad or disconnected.  Sometimes bad connections are "hidden" under the shrink tubing.  The connection at the roller end is the most likely culprit.  Re-solder and cover the connection with new shrink tubing or electrical tape.  If you cannot repair, send into our service department.

Regards,

3rail

[Joe Satnik]

Your welcome, TM.

3rail speaks with much wisdom and experience.

The problem is most likely the bad solder joint (intermittent or open connection) that 3rail describes. 

Another test, just to prove that it is an intermittent or open, and not a short, would be the following:

Put a 3" piece of tape along the top of the middle rail on a normal straigt track portion of your layout. 

Run the engine at a slow speed setting over it.  The bad pickup should sail over the tape no problem, but the good pickup will stumble over it.

If there is no stumble over the tape, your loco may be causing a short at the turnout, and further testing with an ammeter (or other current measurement/detection devices) would be needed. 

Let us know how it goes.   

Sincerely,

Joe Satnik

[Trainman702]

Thanks 3Rail and Joe.  I ran the engine for over 20 minutes and the roller pickup on the front (by the cab) was sort of warm to the touch; however, the roller pickup on the other end was cold to the touch.  I will take the engine in to the train shop near where I live (Roundhouse South) and let their mehcanic take care of the problem for me.  If they cannot fix the problem, I will send the engine in to 3Rail.  What is your mailing address, just in case.

Thanks a bunch guys!

[3rail]

Trainman,

Here is the information for our service department.


http://www.bachmanntrains.com/home-usa/service.php

Regards,

3rail