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Author Topic: electrofrog point shorting while switching.  (Read 474 times)

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Offline Mash Can

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electrofrog point shorting while switching.
« on: January 10, 2017, 09:13:28 am »
Following the advice received on the forum last week, I have spent the last few evenings fixing down points, checking back to back and generally tweaking things until I have sorted out most of my problems.
The back to back correction made an unbelievable difference, but as is the way I am fast learning, cure one problem and another crops up.
I have been left with one set of rouge points which short momentarily as they move across, it happens every time even without an engine on the track.
It is a Peco electrofrog  code 55 point, operated with a dcc concepts cobalt classic motor,
Half way across it's travel it shorts just for a second, shutting the layout down.
I have carefully brushed between the rails to make sure there is nothing there that might be causing the problem and everything looks to be ok, but obviously isn't.
I have spent some time looking for an answer on the internet, but as yet have been unable to find one.
My good lady suggested that I consult greater minds than my own, so yet again I turn to you chaps, any guidance would be greatly appreciated.

Offline longbow

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Re: electrofrog point shorting while switching.
« Reply #1 on: January 10, 2017, 09:22:27 am »
Stating the obvious but have you tried depowering the motor and retesting?

Offline Mash Can

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Re: electrofrog point shorting while switching.
« Reply #2 on: January 10, 2017, 09:32:55 am »
Hi Longbow,
Thanks for your reply, I am hoping to get underneath the board and check the wiring this afternoon, thanks for the suggestion, I will certainly try it.
Being relatively new to this, I an fast learning that what is obvious to most, isn't necessarily so to me, it's quite a steep learning curve, but I'm enjoying it.

Online Bealman

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Re: electrofrog point shorting while switching.
« Reply #3 on: January 10, 2017, 10:43:15 am »
All points on my aging layout are live frog. All rely on blade contact because my complicated signalling system ties up the switching.

There have been probs over the years with sparking and the odd stall, but generally if you keep 'em clean, it's a satisfactory situation.  :thumbsup:
Vision over visibility. Bono, U2.

Offline JanW

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Re: electrofrog point shorting while switching.
« Reply #4 on: January 10, 2017, 11:31:44 am »
You could try to remove the over-centre spring.
It looks as if the switch in the cobalt motor changes polarity of the frog before the point blades move.
The point blades also switch polarity of the frog and if these are not synchronised with the contact in the Cobalt you can get a short.
Without the over-centre spring the point blades will move slowly away from the stock rail without the spring keeping them in place too long.

Jan

Offline terrysoham

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Re: electrofrog point shorting while switching.
« Reply #5 on: January 10, 2017, 12:58:40 pm »
As Jan states, point motors require the removal of the over centre spring which is adjacent to the tie bar.   Use a smallish screwdriver blade to open up the two metal tabs holding the plastic cover in place.  If you're lucky the spring will be visible, if not, it will already have pinged off somewhere.   It will be considerbly easier to do if you can remove the point.
Do NOT remove the centre spring when you are switching the point with a solenoid.
Regards
Terry Metcalfe
Ely and District Model Railway Club
Owner of Neely, modern N scale representation of Ely, available for exhibitions

Offline Mash Can

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Re: electrofrog point shorting while switching.
« Reply #6 on: January 10, 2017, 02:08:18 pm »
Hi Chaps,
Unusual for me, but I was ahead of the game with regard to the springs and all were removed prior to fitting, I'll take a look under the board at the motor this afternoon and see if I can spot anything adrift in the wiring, perhaps a stray strand of wire is causing the fault.

Online Yet_Another

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Re: electrofrog point shorting while switching.
« Reply #7 on: January 10, 2017, 02:20:07 pm »
I have read elsewhere on the forum that if you are using the built in switch to change the polarity of the frog, it is possible that the electrical switch throws just before the point does, causing a momentary short. The over centre spring (which you've removed) can make this worse, but it could still be the case, depending on the length/springiness of the actuating wire.

If possible, try just disconnecting the frog output from the point motor.
Tony

'Things are not done by those who count the cost of every thought or deed.'

Offline terrysoham

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Re: electrofrog point shorting while switching.
« Reply #8 on: January 10, 2017, 03:31:38 pm »
Re-reading the original post......can you confirm that the short occurs when the point has been thrown about half way, in other words neither switch blade is touching the fixed stock rails?

If this is the case then the short could be occurring inside the switch itself.
Unfortunately I don't know this point motor - does it by any chance have a second switch that you could try?  Alternatively could you swap it with one of the motors that you know does work.
If either of these sorts the problem then it is likely that the switch on the motor is faulty and you can take it back.
If it doesn't then we continue looking :-)


Terry Metcalfe
Ely and District Model Railway Club
Owner of Neely, modern N scale representation of Ely, available for exhibitions

Offline Mash Can

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Re: electrofrog point shorting while switching.
« Reply #9 on: January 10, 2017, 04:40:54 pm »
Hi Terry, I have been having a further investigation this afternoon and think I have found the cause of the problem.
All wires are connected properly and no stray strands, so I returned to the point itself and discovered that there is the tiniest amount of movement in one of the switch blades at the end where it hinges if I make myself clear, the blade moves slightly away from the hinge in a longitude direction, as posed to the lateral one it's designed to.
If the blade is pressed together at the joint, no shorting until the point has been switched a few times, then it comes loose once more and the shorting returns.
Obviously there is a problem where the blade hinges, but is there a way to rectify it without replacing the point

Offline PaulCheffus

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Re: electrofrog point shorting while switching.
« Reply #10 on: January 10, 2017, 05:07:03 pm »
Hi Terry, I have been having a further investigation this afternoon and think I have found the cause of the problem.
All wires are connected properly and no stray strands, so I returned to the point itself and discovered that there is the tiniest amount of movement in one of the switch blades at the end where it hinges if I make myself clear, the blade moves slightly away from the hinge in a longitude direction, as posed to the lateral one it's designed to.
If the blade is pressed together at the joint, no shorting until the point has been switched a few times, then it comes loose once more and the shorting returns.
Obviously there is a problem where the blade hinges, but is there a way to rectify it without replacing the point

Hi

One of my points did this years ago straight out of the packet so I got it replaced. Maybe a dab of Araldite Rapid on the exposed metal before pushing it back together but personally I would replace it.

Cheers

Paul

Offline peterj51

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Re: electrofrog point shorting while switching.
« Reply #11 on: January 17, 2017, 12:38:25 pm »
As a complete novice at this,I'm installing electrofrog points on my first layout (DCC). I was going to use Gaugemaster PM10 motors. I've read everything I can, but I think age is kicking in and I'm finding it hard to get my head round the wiring. The PM10 has 3 wires coming out of it. I am presuming one is for power (to the transformer/bus?), one is the points switch, and one is for an accessory? Do I need to add any other wiring to the point itself other than power to the rails? I've also seen that a CDU should be fitted for every 5 points? I want to use a simple toggle switch on my panel for the points. Is that right. If this sounds like a man groping about in the dark, then it's an accurate picture !

Offline newportnobby

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Re: electrofrog point shorting while switching.
« Reply #12 on: January 17, 2017, 01:08:36 pm »
See if this helps you, Peter.............


 

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