hi all,

as per title, and please bear with me i am a novice, i need some help in understanding why on several track positions (always the same) my loco (a marklin digital starter set, red diesel locomotive) stops at low speed. i need to push it a little to make it continue. i tried everything, the rails and the central AC rail are perfecly cleaned, the loco wheels and central plate are clean too. If i switch the track piece where there is a stop point with another identical one, it works ok..... but since there are many of those stop points, i cannot just change all the track pieces, surely there is something that i am missing and need advice for. I checked with a voltmeter all the rails and all the central junctions, they all work flawlessly. even when the loco stops, i check the voltage directly on wheels and the centrale plate while it is stopped, and the current is there.... but the loco does not move. dead stopped. lights off. i have only one loco so i cannot check if the problem is the loco, but judging by the fact that the stop points are always the same on the track, i'd be more inclined to think that there is a problem with the track piece, but i don't know what else to check.

thanks

Fab

Bonsoir Fab
Avec les voies Märklin, tout le monde nettoie les rails mais les picots en tole rouillent bien et cela ne se voit pas (surtout à coté des rails en acier inox).
Pour les blocages sévère je conseille d'utiliser de l'abrasif de carrosserie grade 1500 dans l'idéal.
Finir avec une planchette de bois pour polir et oter les micro-rayures causées par l'abrasif. Attention pas de "papier de verre" ou d'abrasif à grain plus grossier car on ferait des sillons dans lesquels la poussière et la crème de ruban de traction - huille viendrait bien se rappeller à nos soins.
Amicalement
Jean

Can we have a translation please - forum being an English language forum and all. Thanks /BDNZ

Edited by moderator 26 February 2024 16:17:14(UTC)  | Reason: Not specified

Ahhh - what you name the "central plate" seems to be what is called the "pickup shoe", or "slider", or "ski" elsewhere. You could increase the pressure of it by carefully slightly bending down the bronze holding / guiding springs by not more than a millimeter or two. Use a screwdriver or small flat pliers.

I have only experienced this since the sets with smp power supply not older ones. Older locomotives with the new, yes.
Never with the 6627, or the 6021 controller and the 6001 transformer.
I think smp power supply equiped audio amplifiers are also affected by the lower amperage switching. Vintage output and new era are not equal. Vintage class A amps had large heat making transformers. Full Rich low distortion sound at lower loudness volume gain.Transistor switching began above 25% gain, or higher. Modern class AB, C and D type amps have switching across the entire gain spectrum. Much cooler operation especially at lower listening levels, but they require more gain to equal vintage ones.
Just my two cents worth. Perhaps the 6021 was overbuilt to handle heat, having the substantial heat sink on the rear. I have never felt any heat generated by it.

Usually after getting the trains to complete a few runs, they run better. Maybe the decoders and motors warm up.

Try cleaning the problem track areas with Electrical Contact Cleaner which I find often helps. Using ISO at anything other than 99% proof is not good as it contains water, so you will effectively be pouring water all over your tracks.

You've focused on the pickup shoe contact, but I would also check the grounding connection in your loco - clean the loco's wheels. Also, how many rubber tyres does the loco have, and are the wheels with tyres also providing the rail ground as sometimes the tyres lift the wheels off the track enough to provide intermittent grounding. Worst case you might have to wire up another grounding point on the loco's chassis.

hi,
there are 2 rubber tyres in total, they are all in the 4 wheels bank that does not have the pick up shoe (one per side). But i am sure the problem is not on the ground, because when the locomotive stops, lights off, if i take the measure of the current with any central point and any of the wheels, there is always current. i cleaned the central points with 99% ISO, so i don't think that a contact cleaner would help more, but i will try of course. and yes, if i push down with a flat screwdriver the shoe just a tiny bit, the loco restarts.