Hornby 4mt shorting out

Discuss Hornby Model Railway products and related topics here. This includes (Lima, Rivarossi, Jouef, Electrotren).
6412
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Joined: Sun Aug 30, 2015 7:51 pm

Hornby 4mt shorting out

Postby 6412 » Sun Feb 17, 2019 5:05 pm

Hi all
I have a Hornby 4MT which about 12 months old and has a DCC decoder. Today it was running tender first from a siding and the tender jumped the points causing the controller to shut off. Re-railed it and it continued onto and over the next set of points, I then started to run it back into another siding when it stopped and the controller cut out. It has not derailed so I used the “hand of god “ to pick it up and place on a siding, as soon as I did everything cut out again. I’ve checked to make sure that nothing visible was causing the problem and also using a rolling road held the loco off the track with just the tender on the road and then the other way round, both cases the controller cut out. Before I take it all to pieces any suggestion what I should look for.

Many thanks

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Bufferstop
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Re: Hornby 4mt shorting out

Postby Bufferstop » Sun Feb 17, 2019 5:48 pm

It could be a wiring fault between loco and tender, but before looking for that examine the underside of the loco and tender very thoroughly. Magnifier and strong light if necessary. Look for anything that may cause the short circuit. Pickup wipers bent and shorting to frame, loose wire, track pin picked up by motor magnet and clinging to the bottom of the chassis.
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Mountain
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Re: Hornby 4mt shorting out

Postby Mountain » Sun Feb 17, 2019 9:06 pm

Tracing faults is where I prefer DC to DCC. If the loco has a DCC plug and socket, undo the decoder and start by testing from there. It can be easier to trace a short by doing this.

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captrees
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Location: Kalamunda WA.

Re: Hornby 4mt shorting out

Postby captrees » Mon Feb 18, 2019 12:21 am

On my 4mt the wires between loco and tender are too long and I noticed slight wear on the wiring from dragging on the track. Before it was damaged further I twisted the wires to shorten them.

6412
Posts: 44
Joined: Sun Aug 30, 2015 7:51 pm

Re: Hornby 4mt shorting out

Postby 6412 » Mon Feb 18, 2019 1:04 pm

I’ve just had a very quick look at the loco again and I think that there might be a break in the wiring from the tender, need to have a proper look under a better light but if so I assume I can get a replacement lead from somewhere.

Bigmet
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Re: Hornby 4mt shorting out

Postby Bigmet » Mon Feb 18, 2019 1:43 pm

Mountain wrote:Tracing faults is where I prefer DC to DCC. If the loco has a DCC plug and socket, undo the decoder and start by testing from there. It can be easier to trace a short by doing this.

Very much so, take DCC out of the equation for testing, insert a blanking plug and do the work with a DC supply.

Detach loco from tender too for the first test: does one alone cause a short when placed on track? That localises the problem if the short is caused by one alone.

If not, check that the short is still present with loco and tender electrically connected. That's usually a broken connection on the tender with the free end of the broken wire moved into contact with the 'other side' rail or motor lead; because these are only commoned on the loco, the fault can only be revealed when the tender is electrically connected to the loco. (The same type of fault inside the loco will result in it being a dead short alone.)


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