Marx 999 question

Lets start with the basics

a; make sure the drivers are clean

b; lightly lube the axles and both ends of the commutator

c; make sure the screw at the bottom of the brush plate is tight

d; make sure the brushes and commutator are clean

e; check for excessive wear at the brush plate where the commutator shaft is

f; make sure the collector shoe is touching the track with sufficient pressure

Steve

G; no crud in the gear teeth and all teeth present (on the gears).

All good suggestions but if he is jacking up the voltage high enough to burn out a headlight, he may have damaged the reverser coil or burnt the reverser contacts badly.

Thanks "Papa", I followed you textbook to the letter, but this one is different.  Royboy, no curd in the gears either.  I am thinking it is related, as Bill Mc suggests, to the E unit.  Sure a new one on me.  How would a damaged e unit cause this surge of current?  By the way, this e unit was sticking, and I sprayed it pretty well with contact cleaner and it freed it up.  However, when it gets warmed up, it will stick when trying to reverse, and when that happens the motor just buzzes and acts like it is trying to shift, but no joy in Mudville!  It may be toast.......

The circuit for the Marx motor is relatively simple. The highest voltage that can appear across the light is whatever voltage the transformer is supplying. I assume you have other Marx locos that work fine on this transformer. If not, I would switch to another transformer and test it that way. Some Marx transformers have connections for accessories that put out a continuous 15 volts (some may go to 18 volts, I dunno).It's possible that you have something funky going on in the transformer.

If the problem is the reverser and the plunger seems to work OK, then the problem is probably in the contacts (either burned or misaligned). It's a major little project to take the thing apart and fix those. I think most people just toss them out and hunt for a replacement.

Hi, Bill.

I appreciate you help and observation regarding this little problem!  To update you, I pulled the e unit out of the frame and replaced it with another unit.  Ran the motor without the wheels for about 30 minutes without observing any problem.  Put the wheels back on, and ran the assembly for 30 minutes with out problems, and with a bulb in the headlight.  Put it back in the shell, and ran it for about an hour, in both forward and reverse.  All seems well!  Must have been the e unit.  

STILL don't have any idea why the power spike and burned out bulbs!

Again, thanks!  YJ

Congratulations on persevering and fixing the problem.  You should be good for years now.

Thanks, TrainsRMe.

One other thing I should also note here for the good of the cause:  While working on the motor, I also noticed that the small brush springs were exerting more tension on the brushes than I normally see with these motors.  I adjusted them to lighten the pressure, and deepened the small grove that is on one end of the brush to provide better seating for the springs and to prevent them from spinning in the cup - as I had noted one of them doing. (The brush plate is the older pre-war version) The motor now runs much cooler than it did before.

Combination of this and the replacement of the e unit.....Something worked!

Interesting about the brushes. Brush problems with Marx motors are usually just the opposite - that is not enough pressure. This is sometimes caused by a brush spring being a little too long and "snagging" on the inside of the brush holder.