12v trigger for projector screen

jhs6ras

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which of the below cables coming out of the projector screen need to go to the power supply and which need to go to the 12v trigger

long version
in the boredom of covid-19 isolation I have an old projector and electric screen from my mum and dads old house i am trying get up and running and the piece that is giving me trouble is the 12v trigger for lowering the projector screen automatically when the projector is turned on. i am trying to reverse engineer the previous installation and have limited information to go on so thought i'd ask on here. any help would be much appreciated.
 

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Well, by all intents you've got Live Neutral Earth (Brown, Blue, Yellow/Green) and a spare. I'd guess the black is the 12V trigger but it would be a guess. Can you find a manual for the screen online?

Was it working in a previous life or has it never worked? I'm sure my PJ had two control wires, but I may be making that up.
 
thanks Wil, it definitely used to work in the old house. i guess not much care was taken when removing the screen to look at the wiring. there is definitely two cables that go into the 12v adaptor that goes into the projector but not sure how that ties into the 4 wires coming out of the screen.
unfortunatley the screen has no branding on it so i ca't look up the manual.
 
I just found a wiring diagram for a blind motor on another site. Looks like brown is power down, black is power up... might be worth trying that. You need to take the 12V trigger into a control box of some kind to convert the 12V signal to a 230V motor feed...
 
The cable you have pictured is the cable just to the screen and is for mains voltage only.

Without the 12V control box or a switch, the screen is just dumb.

As @Wil S states the brown and black wire are for the up and down.

At a very basic level if you wanted to manually get the screen down.

You wire blue and earth as normal and then brown to positive.

To go back up you would have black to positive instead.

You could do this in a mains switch 3 Way switch.

The 12V box will do a similar thing but will typically use a relay that will close on the 12V signal from your PJ. When it closes it will allow the mains to pass to brown. When it opens it will swap back to black.

Normal forums warning: Please be careful as we are dealing with mains electricity and if in doubt consult a professional.

Do you have pictures of the internal\wiring elements of the 12V control boxes? Should be able to help from that.
 
Just a thought are you sure the motor is a 230v AC motor? TBH its more likely to be a 12v DC motor because its easier to change the rotation of the motor by reversing the polarities.
It would be worth checking 100% because putting 230v through it is gonna make an awful mess of a 12v motor?
 
Just a thought are you sure the motor is a 230v AC motor? TBH its more likely to be a 12v DC motor because its easier to change the rotation of the motor by reversing the polarities.
It would be worth checking 100% because putting 230v through it is gonna make an awful mess of a 12v motor?

No harm in checking but projector screens are generally mains and the cabling photographed is definitely a mains cable.
 

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