Originally Posted by: cookee_nz 
So let me get this right - you are saying it always reliably goes in one direction (let's call it forward) without problems?
I just want to understand the distinction between 'wrong' direction and reverse. It seems you are saying that the only time it will reverse, it when it is actually meant to go forward, and with the lights on for Forward, but that it also only runs in the reverse (wrong) direction for a short distance before stopping??
I'm assuming we are talking a standard mechanical reverse unit?, no modifications to add an electronic reverse or a digital decoder? - I guess you don't recall if it worked correctly before being stored away?
I reckon your 3028 may be equipped with one of the older style 'Drum contact' Reverse Units, at least that's what my parts page is indicating and these operate a little differently.
Assuming we are starting from forward direction....
1st Reverse Pulse - lights only
2nd Reverse Pulse - changes direction (reverse)
3rd Reverse Pulse - lights only
4th Reverse Pulse - changes direction (forward)
It sure sounds electrical, possibly a short-circuit, or a bad connection, possibly the reverse winding for the field-magnet is defective or that portion of the reverse unit is not making good contact.
Sometimes all it takes is to remove the body and watch the operation of the reverse unit in action, then with a small screwdriver, or maybe something like a toothpick, just carefully press on different areas where contact is made, reverse unit, wires etc and see if anything changes - that can help isolate the problem.
Can I point you to the excellent Marklin Service Manual download (scroll down to 'Technical Manuals' - the site is Spanish but the book is English) as this contains a very helpful troubleshooting section along with typical wiring diagrams etc which should help you (in fact, grab all the manuals you can while you are there)
Let us know how you get on.
If you have no joy and you are half-tech-savvy, and have a digital camera or phone that takes short movie clips, record what it's doing, post it to YouTube and give us the link, we'l have it nailed in no time.
Regards
Cookee
Wellington
Sorry Cookee - I'm better at numbers than I am at language.
Also retired medically, so limited income so phone is old & no digital moving camera.
Will try again. Yes its old - purchased mid 1980s - no digital or modifications. Working fine when boxed away.
/* UPDATE - saving message as is; INCOMPLETE */
/* hopefully what I suspect I just saw will provide answer/clue */
/* jump to end for now, or JUST IGNORE THIS MESSAGE */
// I may have answer OR i'll continue with message if its a dead end
[move 1 - forward]
Direction 1 - all is correct, lights indicate direction of travel (white @ front, red @ rear) & it goes correct forward direction.
[reverse & try to go opposite direction; should be backwards]
Reverse engine (with pulse). (sounds & acts normal on pulse)
Lights have reversed ; by increasing power on controller lights get brighter as they should. Lights @ end that was white for forward on 'move 1' is now red & vice versa.
Mostly in this position though - rail car will not move. On occasion it moves slightly in the forward direction (travelling in direction in same direction as forward but now with red lights at the "front" and white at "rear". Speed is approximately that reflected by current being fed engine but it'll never move more than 2-4 rail lengths before stopping.
(of note: if power is greater, its seems to stop quicker (1-2 tracks), if lesser power on the occasions when it moves forward (should be going backwards) it will go forwards 2-4 track lengths; but always in forward direction with red lights at the front)
[stop power - reverse & return to travelling forward]
By reversing (larger pulse) it returns to going forward, with white @ front, red lights @ rear.
Lights correctly change to reflect reversing pulse.
When it should be going backwards; it mostly refuses to move - sometimes travels forwards (but only a short distance; the greater the power the shorter the distance).
When its "refusing to go backwards" while its not loud, there appears to be a noise that reminds me of the noise you hear on reversing - but is very quiet, and could be normal operation sound that I can only hear because its stationary.
Mechanically I'm beginner - haven't touched 3095 yet as have to work out what the "gear" is. The technical reference you pointed to may provide me clues (thank you - i expected a .pdf, but found a directory with lots of .JPeGs which represent each page - is this the correct "technical reference" ??
Looking at it (open), everything appears to work correctly. I've attempted to prod looking for something wrong, can't see it. Reversing unit appears valid; wires match other locos, and all appear attached. I don't know how marklin locos go, as I thought motors used DC only, and polarity of current dictated direction of movement in motor (this is left over memories from high school so i'm possibly way off; was a programmer by trade). Quick exploration with multimeter didn't find anything wrong with leads - but I don't understand what the "reversing unit" does to the power that makes the unit go in the opposite direction.
// STOPPING NOW .. was probing with multimeter again and I think its wheels appeared to go backwards.
// driving wheels were lifted above track as I probed with multimeter and listened to get detail for this message
// fell off my temporary "jack" so will have to setup again, and confirm which direction wheels moved
// could be I have answer - if I don't I'll continue writing.
Chris g
