Mildly weird point motor behaviour - dcc concepts up analog

[DickBrowne]

Hello all, this is likely to be operator error, but I’d like m some opinions if I may. 
 

yesterday I managed to blow two off my IP analog point motors, so today I bought two new ones from my local model shop. 
 

fitted the first line motor, no problem, but the second one showed no signs of life. I have swapped them around and the functioning one still works and the other is still dead. 
 

here’s where it gets weird. 
 

if I connect the “faulty” motor to a 9v battery it works fine, but back on the layout, nothing… 

 

any thoughts? Other than return it?

[kevinlms]

16 hours ago, DickBrowne said:

 

if I connect the “faulty” motor to a 9v battery it works fine, but back on the layout, nothing… 

 

any thoughts? Other than return it?

If it works using a battery, almost certainly not a motor issue.

 

Do you have a multimeter to do some investigation with?

[DickBrowne]

I do - I've belled it out, as we used to say in the networking game, and continuity and voltage are all good. Given that the whole thing works when attached to a battery, I'm guessing that my power supply, which was quite happy when the old motors were in use, isn't supplying enough amperage. Maybe the resistance in one point motor is higher? Anyhoo, I'm planning to swap the transformer out for something a little more hefty this afternoon. 

 

I blame the whole thing on ohms law...

[kevinlms]

2 hours ago, DickBrowne said:

I do - I've belled it out, as we used to say in the networking game, and continuity and voltage are all good. Given that the whole thing works when attached to a battery, I'm guessing that my power supply, which was quite happy when the old motors were in use, isn't supplying enough amperage. Maybe the resistance in one point motor is higher? Anyhoo, I'm planning to swap the transformer out for something a little more hefty this afternoon. 

 

I blame the whole thing on ohms law...

Do you know the ratings of your power supply - should be on the label?

[DickBrowne]

The original was 1a @12v. I’ve since replaced it with a variable output supply, and at 12v it’s rated at 1.2a, but at 9v it was closer to 2.5 (its behind a board now so can’t get to it). 
 

At 12v, the points were still struggling, so I tried maximum output - 15v, but that was worse. Turned it to 9v and everything in the garden is looking rosy. 
 

Turns out that a is more important than v in some instances. I’m guessing that the resistance in the new point motors is greater than the old, maybe a different factory in China? Maybe just need to bed in? Anyway, ohms - not just a good idea, it’s the law!

[5BarVT]

Think it’s the power law you’re falling foul of, not ohms.  But that’s being pedantic and spoiling your good one liner.

Paul.

[DickBrowne]

You are right of course, but when I did my electronics training in the 1980’s we referred to the power formula, rather than power law (which was a statistical analysis thing rather than electrickery), and I reasoned that I wasn’t able to come between the world and a reasonable punchline :)