If it is one particular car causing the problem, check the wheel spacing on it. It could be the wheels are too close together or too far apart.

Ray

Is it happening on both turnouts? or just the one? It does sound like the wheel spacing is off, measure the spacing on the fright cars and compare with the passenger cars. the wheels slide on the axles and can be moved easily. Sounds like the spaceing is too narrow and the wheel is dropping off the frog.
To prevent unnecessary shorting to your CS, I would remove the turn out and an few sections of track around it.
run the cars manually across and visually inspect the clearance. If you have an ohm meter connect it to the track and see where it makes contact. Even a simple battery, flash light bulb and some wires can be used to indicate where the short is. Then when the you have verified that the problem is fixed connect the section of track back up to the layout.

Is the wheels are Marklin 3-Rails?

I through someone else changing to 2-Rails?

Welcome to the forum, Leng. (Please add country to your profile )

I have the same set but don't recall that exact problem with the curved turnouts. I suggest that you check the wheel distance as suggested above. Here is a piece of information on wheel measurement:

Hello,

I had a similar problem with the curved turnouts from my 29859 Set. They were exchanged by the dealer and I have not had a problem since.

Have you pinpointed the exact spot where the short is occurring?
Are the sparks visible on the outer or inner side of the coach? (towards the outside or inside of the layout/curve)
Are the sparks from the outside or inside of the axle? (underneath the coach or on the side)
Once you have located the spot and it turns out to be a particular stud, you can try to bend that stud further away from the rail so that it does not contact the wheel.

I find it rather strange that this is occurring with only the four green coaches and not with the freight cars as they all likely have the same axles/wheelsets.

Do you have any cars/coaches other than those from the start set?
If yes, do they have the same problem?

I am not 100% sure if I understand what you mean by merged end. Do you mean going from one of the dual tracks to the oval or going from the oval to the inner or outer passing track/station?

Does the problem occur in both directions? (entering or exiting the switch).

From what I think I understand, you are having a problem on the inside of the train when the train is on the outer track. Furthermore, the same problem occurs (reversed) on either switchtrack. Is that correct?

If the train is moving at speed, a spark may occur. If the train is moving slowly, this would result in a longer short circuit, possibly slowing or stopping the train and causing the CS to reset.

What speed (%) is your train moving?

One thing that you could try is to swap the wheelset from one of the coaches with one of the freight cars and see if the problem moves with the wheelsets.

Regards

Mike C

Welcome to the forum, Leng.

One easy way to make sure: just place a piece of cellotape on the outside of the puko(s) in question or apply some nail polish (quick drying).

You need not to be. Pukos do not brake like glass. I have done it on a curved turnout - even too much and then bend it slightly back again - no danger. You need a pair of flat-nose pliers of suitable size to do the job.