Points Problem

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Fairweather
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Points Problem

Postby Fairweather » Sat Apr 17, 2010 4:57 pm

First of, apologies if this has been discussed before, I did search, honest. Anyway. The problem is that whenever a loco pases over the points in a particular direction, the loco stalls, the DCC controller display starts flashing, and the top half of the displayed numbers disappear. The points are the standard hornby points. It doesn't appear to be a fault with the loco, as there are no problems with any other points. Does anyone know what could cause this?

m8internet
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Re: Points Problem

Postby m8internet » Sat Apr 17, 2010 6:55 pm

We would need to see a wiring diagram

Are you powering the point motor accesory decoder from the track or an accessory bus?

What type of equipment is in use (transformer, control module, accessory decoder, etc)?
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hobby boy
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Re: Points Problem

Postby hobby boy » Sat Apr 17, 2010 7:10 pm

Could there be a short circuit when the train passes over the frog??

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Dad-1
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Re: Points Problem

Postby Dad-1 » Sat Apr 17, 2010 8:44 pm

Almost certainly a short on the frog, I'd also take a bet that you're running a loco with traction tyres and probably running quite slowly.
I have had this with 2 x Hornby DMU's, turn the loco through 180 degrees and the problem may vanish - so long as it's facing that way. I can't give a difinitive answer, only that as mine have been run more the problem has receded although there is still a minimum speed under which I may have problems.

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Sprintex
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Re: Points Problem

Postby Sprintex » Sat Apr 17, 2010 9:28 pm

Either that or a slightly bent-out point blade meaning it comes too close to the inside of the passing wheel - got this problem on mine at the moment. Pair of small pliers should fix it :wink:


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Brianetta
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Re: Points Problem

Postby Brianetta » Sat Apr 17, 2010 10:23 pm

Fairweather wrote:First of, apologies if this has been discussed before, I did search, honest. Anyway. The problem is that whenever a loco pases over the points in a particular direction, the loco stalls, the DCC controller display starts flashing, and the top half of the displayed numbers disappear. The points are the standard hornby points. It doesn't appear to be a fault with the loco, as there are no problems with any other points. Does anyone know what could cause this?

It's shorting out, and you're using a Hornby Select. I know, because mine does exactly that when it's shorted. Look carefully at the loco's wheels as it passes the problem area. I once had this caused by the points not lying perfectly flat - before I bought my baseboard.

Fairweather
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Re: Points Problem

Postby Fairweather » Sat Apr 17, 2010 11:03 pm

Brianetta wrote:It's shorting out, and you're using a Hornby Select. I know, because mine does exactly that when it's shorted. Look carefully at the loco's wheels as it passes the problem area. I once had this caused by the points not lying perfectly flat - before I bought my baseboard.


Spot on about the Select. The point is flat though (or as flat as it ever can be). The engine in question is a hornby Merchant Navy, so no traction tyres. The only solution I've found so far is to hurl the loco at the points- which isn't much of a solution. Its a simple run around loop- so there is no complicated wiring, and the points are manually operated. Is there a way to stop shorting, short of ripping out the points? Thanks


Edit- the problem doesn't seem to be caused by the wrong blades touching the wheels.

Brianetta
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Re: Points Problem

Postby Brianetta » Sat Apr 17, 2010 11:33 pm

Check the back of the wheel near the plastic crossing (the "frog") of the points. The moving parts are never a problem on a regular Hornby point, since even if the wheel touches the blades, they're at the same polarity. The crossing is where rails of opposite voltages get really close to each other. If the back of a wheel can touch the opposite rail whilst running on its correct rail, it'll short across that wheel. It can short across other wheels on the same side of the loco if it has a pickup.

If this turns out to be the problem, one of your loco's wheels might have been pressed hard into its axle, and moved inwards. This is correctable. The normal distance between the backs of the flanges on the same axle should be 14.4mm, and they can normally be moved with finger power alone. I once re-gauged a loco's wheels after this sort of trouble using the outside of the jaws of a pair of pliers. Just be careful if you use that trick, it's easy to overdo it.

Fairweather
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Re: Points Problem

Postby Fairweather » Sat Apr 17, 2010 11:54 pm

Yes! Thankyou Brianetta (and all others who have assisted). It WAS shorting at the crossover. A small piece of double sided sellotape at the crossing has solved the problem. Thank you all once again. I was getting worried for a moment......

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sishades
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Re: Points Problem

Postby sishades » Sun Apr 18, 2010 11:37 am

Instead of sellotape use spme nail varnish. Sellotape will leave a sticky residue if removed.
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