strange behaviour when hooking screen to optoma gt1080 12v trigger

Discussion in 'Projectors, Screens & Video Processors' started by indgirl6, Jun 11, 2015.

  1. indgirl6

    indgirl6
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    hi all, i am a newbie when it comes to home theater. We finished our basement and did a home theater setup. I am using the optoma GT1080 projector and an Elite Spectrum 84 inch electric screen. I am trying to use the 12v trigger function so that the screen comes down when PJ is turned on and retracts when PJ is turned off.

    the screen has an ethernet port and uses a standard rj45 cable and the PJ has the 3.5mm jack for the trigger port.

    well i did the connections and nothing happens when i turn the PJ ON / OFF. however, if the screen is down, and i power OFF the projector (nothing happens), then if i remove the 12v trigger (on either the PJ side or the screen side) and then connect it back in, the screen senses the trigger and retracts automatically. this only happens when the screen is down and i OFF the PJ, it does not work the otherway round when screen is up and projector is ON.

    can some one advice what i should do? i Called Elite and they are trying to sell me some IR stuff which is very expensive
     
  2. zonedetector

    zonedetector
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    Try reversing your wiring, it sounds like you have the up and down reversed. Also make sure that in the projector menu the 12V Trigger is switched to on.
     
  3. zonedetector

    zonedetector
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    Where you based ? if its local I would bob by and sort it for you.
     
  4. indgirl6

    indgirl6
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    Thanks for your response. i am not sure what you mean by reverse the wiring, how do i do that?
    Also, this morning i checked it again (did not touch or make any changes). and now when i switch off the projector the screen comes down, so looks like you are right. I am in Millburn, NJ
     
  5. indgirl6

    indgirl6
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    the connection i have made is as follows:
    a regular RJ45 (cat5) cable connects to the ethernet port of the elite screen and runs all the way to the PJ. Then i used an "RJ45 to 3.5mm adapter" that i purchased from ebay, the other end of the RJ45 plugs into the adapter. the 3.5mm Jack end of the adapter is plugged into the 12V trigger port of the PJ.

    I did confirm that the 12V trigger is set to ON from the PJ menus
     
  6. mca

    mca
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    From what you've said you're using a standard RJ45 cable that's fully wired (i.e. the pins in the plugs on each end are connected like for like). The question now is; what pins in the RJ45 to 3.5mm adapter are connected?

    A quick search turned up the pinout here for Elite screens (I assume it applies to all of them but don't know for sure), this has the trigger set-up as 12V on pin 7 and ground on pin 8.

    Another quick search turns up the manual for the Optoma GT1080 here (from the European site), this has on page 47 the 3.5mm jack with the outer as ground and the middle as "IR_IN & detect" so I'd assume that's what takes the 12V.

    So, you need to find out whether the RJ45 to 3.5mm adapter you have connects pin 7 and 8 from the RJ45 side to the outer and middle of the 3.5mm side (pin 7 to the middle and pin 8 to the outer).

    Hopefully that makes sense and you can see where I'm coming from. I could of course be wrong, I'm sure someone will be along soon to correct or agree...

    Bear in mind I'm no expert and you're on your own to satisfy yourself that this is correct.
     
  7. indgirl6

    indgirl6
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    thanks again for your response & time, i really appreciate it. I see what you mean, but i have no clue how to check those things. the Screen did come with an rj 45 cable that was like 12 inches long, one end the cable was cut open to expose 2 wires (just like the image you linked). i guess i wsa supposed to somehow extend that cable and fit it with a 3.5mm connector at the other end.. i had no idea how to do that so got a long rj45 cable and used the adapter.. will try to see what else i can find on this..
     

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