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Can anyone help with a photo or diagram of the wiring connections on the rear of the wiper motor please? Model CRT. Before going any further with the one that I've got I'd like to bench test it. Is it just a matter of connecting + and - to a battery?

With this lockdown situation I can't just run to my helpful friends at TR Enterprises.




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2 hours ago, Ian Lynam said:

Thanks for your replies.

I've attached the photo to try to clarify which terminals I should use! There appear to be 5 possibilities. Obviously electricals aren't my thing!



AlanT on this forum is your route for repair.  Send him a PM if you need to.

The two wires poking out the back of the motor are positive or negative. They do not connect o earth in the motor.  To test connect pos and neg power leads to each of these wires.  If it does not go disconnect immediately.  5 amps would be a maximum current draw I would expect to see at start up and lot less when running.

To finish the motor - Sleeve the two wires with insulation and bend each one to one each of the two identical grub screw terminals. Trap one each wire under one each grub screw.   These grub screws are the two connections for the wiring loom.  One is power from the switch the other goes to the body earth.


Peter W

PS as Roger has stated the grub screw with the lock nut is the armature end float.  If this has been messed with I suggest slacking the nut, unscrewing the screw half a turn, then screw it back in gently till resistance is felt, then turn back 1/2 turn and lock with nut.  This can be fine tuned once the motor is running to get the correct armature running end float.

Take the lid off the gearbox and be sure the thing is not jammed up with congealed grease. - if so wash it out and renew.



Can be seen here image.png.df6a69c1854e4bca5ea276c00d393b66.png

Edited by BlueTR3A-5EKT
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Not an answer to your question, but a problem with the wiper motor not running, in my experience, is that the tiny plastic insulators that holds the spring that holds the carbon brushes together against the collector get old and brittle and breaks.


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The terminals just join your feed wires to the two wires sticking out of the plastic cap.  On these little motors it's really easy to break something, like those little wires.  So be careful.

The big screw is for end-float adjustment on the armature.  If you have fiddled with this, back if off and re-adjust with the motor running.

If you have slackened the screws in the corners that hold the plastic cap in place you may find the motor won't go. This is because the cap has moved and jammed the armature.  You have to find a "sweet spot" then tighten the screws.  Great production technique. But then this is 1940's design.

I put them on 5V supply and jiggle for maximum speed.   DONT APPLY 12V for very long if it does not run. You will burn out the armature.

By the way I've done two-speed conversions of these for a couple of Forumites.  Worked OK.



Edited by AlanT
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