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pcu1 to peco points wiring please help

7836 Views 12 Replies 2 Participants Last post by  chrismac
Good evening all

Please could anybody help , i have a gaugemaster pcu1 , and have wired peco points to them as shown on the gaugemaster instructions , but if i switch between c1 c2 and c3 all the points on that swich work , allthough they all have seprate commoms to the right terminals , i have the dioeds as shown on the gaugemaster insturctiuons , what am i doing wrong ? , the motors i am using are normall peco motors , please could anybody give me a diagram , please
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Hi Denver

Looking at
I you sure you have the diodes the right way round?
They probably have markings at one end which goes to the terminal a or B

On the point motor the terminals on one side should be joined to form the common the other side go to A or B

hi chris

Thats what i have done , but switching between c1 c2 and c3 , operates all points on that switch , in one go , it does not seem to mater to much where c1 c c3 are switched ?
I am I right in assuming the is a common terminal for each switch?
C1 C2 C3 C4 C5 C6
There is only 3 commons , that is one common for each set of 6 point switches , i have been looking on the net for the past two hours and one post saids that the diodes should be mounted acrost the coils as the gm instructions show sleep motors and not peco standard motors , i am getting confused ...many thnks
OK got it, I think, it's 3 groups of up to 6 motors per group

The Seep and PECO motors are the same except the Seep is on a board.

It works by +24v DC on C1 going through the coil (SET or RESET) through the relevant diode depending on the switch on the panel to negative.

Disconnect all the diodes
Do you have a meter to check that +24v DC is between C1 and A1 or B1
Should have said operate switch for point 1 (assume it's is a non locking central off)
i will check that tomorrow and let you know, many thanks for tonight speek tomorrow thanks ..
I've dug out the instructions for a Seep motor (bought one to try and stayed with Peco)
According to that, the diagram I am using is wrong (thought it a funny way to wire up but they make & sell it)

The common should be negative so the diodes are the wrong way round.

Using one motor change the diodes round and try it - if it works
Connect up the next motor to Group 2 and try that

will stay on line till we come to a conclusion

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OK speak tomorrow try out my previous first.

Hi denver


I have spoken to the electronics man (Greg) at Gaugemaster today to confirm the diagram is correct and how the PCU1 is wired internally.

The COMMON TERMINALS C1 C2 C3 ARE POSITIVE and are fed from the rotary switch.
The PCU1 centre-off switches then provide the path back to NEGATIVE to make the circuit.

The diodes as shown in the diagram are the correct way round (silver ring on the end is furthest from the point motor).

On the PECO point motor the terminals on one side should be joined together and wired to the relevant C1 C2 or C3 - that I believe is what you have done.
They recommend that you solder a diode DIRECTLY to each of the terminals on the other side of the motor so that the silver ring is furthest from the motor (you can shorten the lead to suit), then solder wires onto the free ends of the diodes and connect one to the A terminal the other wire to the B terminal on the PCU1. Again you can shorten the diode lead but use a piece of insulation tape over each joint to prevent shorts etc. - heatshrink would be better but if necessary you could fit it afterwards when you know it works, a quick touch with the soldering iron will make it shrink.

The soldering of the diode directly to the motor is to try and eliminate errors and it is easier to bring up to 6 wires together for connection at the A and B terminals rather than the ends of 6 diodes. The diagram needs expanding to show this more clearly.

I drew out the circuit and without the diodes there is a problem with the current getting into the wrong coils and so operating, this has nothing to do with Back EMF as mentioned in some other places and it can be safely ignored in this application. The important thing is that regardless of the Common used each point motor must have its own diodes arranged as shown and the wires taken back to the A and B terminals.

The common mistake is fitting a pair of diodes to the A and B terminals then connecting the wires from the motors onto the free ends, that allows the current to flow around the other motors and fires them regardless of their group on the C terminals.

For your interest and information if you were using a standalone Gaugemaster CDU the supplied diagram shows the common wiring as negative and the centre off switches are on the positive side - these PCU1 are backwards when compared to the standalone. Maybe it should be called a feed rather than a common.

Let me know how it goes

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Hi Chris

Thank you so much for all your time and help , if only eveybody was as helpfull as your good-self , i now know wha i have done wrong i was puting the diode out the back then joing another one in series , hence i was getting back current to the diode in line , i have now made a block of diodes that all end up at the gauge master end on all seprate circuts and it works fne , i do think the instructions need to be re-written for the gaugemaster , thank you so much for all your help and hope to see you at a show one day , many thanks to you chris , have a great day .........
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