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3 way point shorting


philsandy
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Electrics is not my strong subject.  I have wired up a 3 way point as in the attached diagram, there are no motors involved, operated by slide switches.

I’m getting shorting.

Wired up SW1 first and worked fine both routes A to Y  and A to X .

When I wired up SW2 A to Z works but polarity is not being switched, loco runs thru to Z when SW2 is at either position, when SW2 is set for route Y loco causes short as soon as it contacts crossing (purple).

 

 

I have followed the wiring as per diagram, the only difference I made is shown on the second diagram (arrowed), I have soldered a wire directly between centre terminal on SW1 and terminal on SW2 rather than teeing off the wire as in diagram. Could this be a factor? Can anyone suggest where I have gone wrong?

3 way point.jpg  handed.jpg

Edited by philsandy
updated, again
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1 hour ago, RFS said:

Have you used IRJs (insulated rail joiners) on the 2 green and 2 purple exit rails?

 

Robert thanks for your reply, I've not used rail joiners, just gapped the rail joints. I've just double checked and one of the joints had closed up, (had the baseboard stood on its end when wiring, probably happened then) so adjusted it. This has cured one of the short faults, but Y route is still shorting and Z route works when SW2 is in either position. 

SW2 is not switching polarity.

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16 minutes ago, philsandy said:

 

Robert thanks for your reply, I've not used rail joiners, just gapped the rail joints. I've just double checked and one of the joints had closed up, (had the baseboard stood on its end when wiring, probably happened then) so adjusted it. This has cured one of the short faults, but Y route is still shorting and Z route works when SW2 is in either position. 

SW2 is not switching polarity.

 

Sounds like perhaps SW2 is faulty? Or it's not powering the frog and and engine with long wheelbase is able to traverse it OK?

 

With plastic-based track (I'm assuming you're using Peco?) I would always advise using IRJs for electrical gapping, as otherwise the gap can close up in hot weather. Don't ask me how I know!

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21 minutes ago, RFS said:

 

Sounds like perhaps SW2 is faulty? Or it's not powering the frog and and engine with long wheelbase is able to traverse it OK?

 

With plastic-based track (I'm assuming you're using Peco?) I would always advise using IRJs for electrical gapping, as otherwise the gap can close up in hot weather. Don't ask me how I know!

 

Points are hand built on plywood sleepers, track is C&L. I tested the switch with a meter, it seems to be OK. I'm wondering if the fault is in the construction of the point itself.

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After further investigation:

The problem is SW2 is not switching polarity of the last crossing (purple).

 

I put a meter on SW2 and found there was no power going to it when SW1 was set at Normal, which it needs to be at for routes Y & Z. When SW1 is Reversed (route X) there is power to SW2 and it switches polarity for routes Y and Z. Of course when the loco contacts the other crossing assembly (green)  it shorts, as it is the wrong polarity.

Do I need to swap the wires on the outer terminals on SW1 only , or also on SW2? 

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