PM20 wiring

[Brian]

I've done away with the wire linking each switch centre tab. Instead, I have connected a green wire to a block which then connects to the CDU negative.

Points 1, 2, 3 and 10 now working. Connect 5 in the exact same way and everything stops again.

I can see your logic re a common terminal block and all the middle tabs of each switch are wired to this block. All this blocks terminals connect together BUT THEN IT SHOULD GO TO THE CDU POSITIVE output.
Out on the layout, all PM20 motors GREEN wires all connect onto one common wire that runs back to the CDU NEGATIVE output terminal.
Each PM20 motor then has two remaining wires, a RED and a BLACK. These go to the outer tabs of the switch that is to work that motor.
Each switch MUST be a non locking sprung to centre off type.

[andy757]

Call me thick, but what I fail to understand is that motors 1,2 , 3 and 10 work fine so my wiring to them must be correct. I did follow your diagram Brian and those 4 work.

As soon as I connect motor 5 in exactly the same manner as the others, they all stop working which tells me there is a problem with either the switch for motor 5, or the motor itself is causing the problem.

[Steve M]

Try a different switch and/or motor. If the problem goes away then the previous components are at fault, if it doesn’t then there must be a wiring issue.

[Brian]

As you're using a terminal block from the CDU Positive and form there onto each switches middle tab from that block, when one fails/causes a short remove that switches wire from the block. Has the problem gone away? If so look at the switch, is it the correct non locking type? Is there any whiskers of wire connecting middle tab to one of the outer tabs? If all OK replace the switch with a new one and reconnect wire to block. Re test. Has short gone? If not replace motor and retest.

[andy757]

CDU positive has one lead going into a block. Then each switch has a lead from that block fed to their centre tab.

Red/black from each motor go into a block in the control panel. Red/black then go off to their respective switch.

I changed motor 5 for another new one. Problem still remains so the motor is ok. I changed the switch (again) and now it works fine.

So out of 15 new switches I bought, 3 are faulty !

I'm now going to follow the exact same wiring logic for motor 4 so if you don't hear from me again today I have either (a) got it working or (B) have left the country and taken up sailing

I may return....

[andy757]

Guess what......

Moved on to the next switch and I have the same problem.

I'm now thinking most of these switches I bought are faulty so I guess I'll have to buy another lot.

The interesting thing is that when I unscrew the switch from the panel, the green LED on the CDU flickers. The solder joints are ok and no exposed wires as I have shrink wrapped them.

[RAF96]

Prove each switch by setting up a simple battery powered switch left and switch right lights circuit. If the lights work reliably the switch is good. Good switches go into one pile, dodgy switches go in the bin or send them back.

Prove your circuits by replacing the toggle switches with a choc block, then use a loop of wire to prod across each ‘switch’ location at the choc block. If the point motors work then you know the main point circuit is good. If not it needs rectification until it does. Once happy put the real switches back into circuit.

Rob

[andy757]

Could anyone possibly provide me with a link to somewhere reputable where I can buy these miniature centre off switches ? I'll give the last guy a wide berth as at least 5 of the last one I bought seem faulty.

[Brian]

These should be OK, Rapid are a good company https://www.rapidonline.com/salecom-t80 ... ch-75-0086
Or https://www.bitsbox.co.uk/index.php?mai ... cts_id=876

[andy757]

Thanks Brian. I buy my wire and connectors from Rapid so I will order a load of switches. I think after my holiday I will bin the others and start again.

Appreciate everyone's patience with me.