Okay all I am new at all of this.

I just got a used Marklin HO set. When I first tried it I could get it to go forwards or backwards but now it only goes backwards...no matter which direction I place the locomotive. What is up?

email ybicm2@gmail.com

M2

Classic Maerklin engines come with a electro-mechanical relay which trips when it receives a voltage surge of 23-24V AC. Newer Maerklin engines have an electronic relay or digital decoder which reverses the direction.
If you have a blue transformer, then you likely have an older Set. If you have a white transformer, it is likely more recent in origin. If you have two control units (one with a knob and buttons), then you likely have a digital or delta set.

I need a little more info, so I will try to narrow down the symptoms.

1) You say that the lok runs only in one direction. I think that you mentioned that if you take the lok off the tracks and turn it around, it still runs in the same direction (clockwise or counterclockwise as the case may be). Are you able to contol the velocity (speed) using the controller? If no, make sure that the track wires are connected to the red and brown connectors and not to the yellow and brown ones at the rear of the transformer.
If yes, what happens when you try to reverse the direction from the transformer? If the lok still moves in the same direction, but goes faster, it is possible that it is not receiving enough voltage to trip the reverse unit. On older models (1960-1975 or so), the electro-mechanical reverse unit had springs that were designed to return the reverse mechanism to the start position. If the spring is not strong enough, the reverse unit may not fully reset.

At this point, you should remove the shell (housing from the lok) and let the lok run (chassis only) so you can observe the function.

See: http://www.maerklin.de/d.../suche/ersatzteile.html# (Right click and select "Open In New Tab")
Enter 3000 (or the number for your item) where it says Artikel Nr. It will display the internal elements of a basic steam engine (3000) or your lok. The classic reverse unit is #24 and the spring (Item 7194) is part #25.

If you enter 3338, you will see a more modern electronic reverse unit under #17. This type of reverse unit cannot be adjusted by the user.

If you enter 3434 you will see a delta (electronic/semi-digital) decoder. If you enter 37460 you will see a digital decoder, both of which cannot be manually adjusted. The full digital decoder may be adjustable with the right control unit (programmer).

If your reverse unit looks like the one from the 3000 lok, check the spring to make sure that the reverse unit returns to the start position. You can manually trip the reverse unit and see if it reverses. If you can reverse it, then you likely need to replace the spring.

If your lok is like 3338, your lok is likely receiving insufficient voltage to activate the reverse unit. If you have a local dealer or know somebody who has a Maerklin set, can you test the lok on their layout or with another transformer?

If your lok is like 37460 and has a modern delta or digital chip, your problem is either insufficient voltage (transformer) or a problem with the lok. (See below for additional delta/digital suggestions).

Now, we will go to the Maerklin site to see if we can find your transformer. Go to: http://www.maerklin.de/d.../suche/produktsuche.html

Enter 6646 where it says Artikel Nr., click on Suchen. A photo of a white transformer should be visible below. This is a modern analog transformer.
If you enter 6021, you will see a basic digital controller (Requires a separate 6002 or other transformer). If you enter 60652 or 60653 it is a modern "Mobile station" handheld digital controller.
If you enter 60213, you will see the modern "Central Station"

If you have a digital controller (6021, mobile station or central station), keep reading.

If you are running delta or digital and you have changed the address that you are controlling, the lok (other address) will continue to run according to the last instructions you gave it. If this is the case, the lok would no longer respond to any commands (speed, direction) until you reentered the digital code to access that lok. This would mean that the lok would continue to run all the time and could not be controlled at all. The only way to stop the lok (other than entering the code) would be to use the emergency stop key.

A delta lok that has an address assigned would not respond on an analog layout and would just sit still, so we can eliminate that as the problem. If you have a delta lok and are running it using a digital controller and you have not set a delta/digital address, the lok would run at high speed and not respond to any commands. You would have to assign an address before the lok would respond to any commands.

If you go to the Produktsuche or Ersatzteilsuche and enter the item number of the Set that you have (if you have the box or know the model number), you should be able to see details on both the item and parts.

If you have not been able to solve the issue using the information above, please tell me the set number and more details and I will try to be more specific.

Regards

Mike C