Bit of an odd one

[Marcyg]

Has anyone had this before? My layout runs an NCE SB5 as it’s control centre, with an additional 3 Tam Valley boosters for other sections of the layout. I was having real issues with locos stalling and screeching when they crossed from one power district to another, namely from the NCE powered track, to the Tam Valley track. My colour coding is black and red for the bus wires and droppers, I’ve been very careful to get everything matched correctly. After a bit of research I reversed the polarity to the tracks controlled by the NCE hub, and the trains run perfectly, even though they are technically not wired right. It’s not a help question, as I solved it, but just thought it was a real odd one

[WIMorrison]

Not really that odd as DCC is an 'AC signal' rather than a DC voltage and the red and black don't have the same meaning as they do with DC where red is positive and black as negative since the are both positive and negative, just at opposite times what has happened is that your Tams and NCE kit were 180 degs out of phase.

 

All it means is that Tams have chosen to wire it one way and NCE another way, I am sure you will find that other makers would have exactly the same compatibility issue with other brands for the same reason.

 

good tip for people though it to remember to ensure that the boosters and main controller are all in phase with each other.

[RAF96]

As most power district boosters also act as a reverse loop module it doesn’t usually make any difference from a user viewpoint if there is a ‘polarity’ i.e. phase mismatch between makes of kit as the RLM element of the booster swaps things over as required. If you think about it the kit is starting up in one of two polarity states (0 or 180) and will auto-flip to the other as required - such as entering/leaving an isolated district/reverse loop from this way or that.

 

You would normally only notice this in practice if like me you were trying to ‘scope’ both of these channels at once (controller and booster). The phase crossmatch caused a double short (DCC A to B and B to A) and immediately tripped the kit. As stated by WIM try to check and match your phasing because as you have found not all kit self-compensates.

 

Rob

[Ron Ron Ron]

....what has happened is that your Tams and NCE kit were 180 degs out of phase.

 

All it means is that Tams have chosen to wire it one way and NCE another way,.....

 

 

A bit pedantic I confess, but in case of any mix-up, note that Tams is a completely different DCC manufacturing company, based in Germany.

Tam Valley Depot is an American company.

 

 

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