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I purchased a 4090 off eBay recently; it arrived last night.  It is intended to be part of a set I am giving a friend's children; this family is not train people, so I want them to have a trouble-free experience.

 

I tested the 4090 using the MPC MoPac GP-20s I also bought for the set.  As a control for the test, I tested the engines first on my KW, and they run very well on it; the e-unit was very responsive to both teh throttle and the Direction button.

 

With the 4090, however, the e-unit had touble tripping, and the forward position failed over 60% of the time using the Direction handle.  Most but not all of the failures were when I was using posts U & A (6-16 volts); it also failed sometimes when I was testing the U & B posts (0-11); U was the 3rd rail in both cases with A or B common.  If the direction handle is bumped just a bit toward the whistle side, the loco slowed down and growled with dim lights.

 

Further, the unit smelled funny when I used the direction control--not like burning inulation but not a "happy" smell, either.  The humming inside the unit was not constant but varied in tone and loudness.

 

I am guessing that the rectifier for the whistle control is failing; I am not sure about the direction control issue, but they seem to be connected,a nd not just because they are the same handle.

 

So I ask the collective wisdom of the forum for help with the diagnosis and cure.

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The rectifier's condition would have no effect on reversing.

Based upon your description, I would guess that the reversing / whistle switch is in need of some attention. 
The switch assembly probably needs a good cleaning, and the little retainer (looks like a top hat) may have slipped, or completely fallen off.

The odor might just be dirt, or old lubricant on the switch surfaces. IMHO, those surfaces should not be lubricated, but some people do. The old lub could be causing the smell, and affecting the operation.

Thanks, C. W.

 

OK, I pulled the shell off and saw no obvious problems.  I hooked it up so that I could observe the innards in action (and, yes, I was VERY careful to avoid touching anything inside while it was powered and operating).

 

When I pulled the lever to trip an E-unit, a puff of smoke came from the reversing switch.  I don't mind smoking trains, but I dislike the thought of a smoking transformer!

 

Any recommendations from anyone?

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OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

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