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Electric DRH screen problems

Discussion in 'Projectors, Screens & Video Processors' started by reggs, Nov 12, 2003.

  1. reggs

    reggs
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    I've just bought an electric DRH screen. Took 2 days to turn up and is as per spec at 8' wide and 16:9 aspect. Build is okay, but not as good as the manual Procinema it is replacing.
    The casing is considerably smaller though, as I opted for the Slimline version. Motor noise is very noisy indeed and a bit crap to be frank.
    There is also very slight curl down both side black bands. The Procinema has always looked like a solid fixed screen! Anyway, as this screen is easily half the price of the other electric screens I've seen and the straight 1:1 matt material is very good, I'm fairly happy :)

    I have some questions that I'm hoping someone out there can help me with though.....

    1. There is no way externally of setting the drop!!! other than to use the simple direction/on/off rocker that came with the screen. I wanted to replace the very simple up down rocker switch with a relay circuit, powered from the 12v trigger on my Sony Receiver. I'm therefore going to have to take it down and apart, in order to figure out if the drop can be adjusted internally. Does anyone know if the drop adjustment can be made simply inside?

    2. Am I going to need a normally closed relay with the rocker switch (or its wiring as it will be removed) effectively locked in the go up position? i.e. When it receives the 12v trigger which is a constant 12v, the normally closed contacts open and it then makes the down connection side of the rocker probably by powering another relay. I'm having trouble thinking how to do this properly and have read Kramer's post :confused: Anyone recommend the circuit / relay(s) as I can't find a normally closed 12v relay?

    3. The rocker either powers up or down and is usually in the central off position. I suspect (or hope) there are maximum travel switches inside the casing but is the motor likely to be powered all the time in the fully up position with the rocker switch pressed up? There is no noise from the motor when its fully up and the rocker is kept depressed. I'm worried about burning out the motor and can't tell until I dismantle it if its always powered when fully up with rocker still depressed.

    Any thoughts, help etc appreciated.
     
  2. reggs

    reggs
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    Just found a simple chageover relay for £1.50 at Maplin that should make this a doddle :)

    Just need to know if the motor is always powered in the rocker up position now .... ?
     
  3. WeirdFish

    WeirdFish
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    I have the same screen and i agree the motor is a tad noisy, but hey does that really matter.

    On the casing there is a small hole on the left hand side giving access to an adjustment screw which I'm guessing is something to do with the drop. I've not tried it as mines fine as is. Well it will be once I get the Z2. [drumming of fingers]

    HTH

    :)
     
  4. reggs

    reggs
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    Thanks for that WeirdFish.
    Yep, I took the side casing off this evening and found the limit switches (they're really screws) which are just below the hole. Only the roll up height is adjustable through the hole, as the 'drop' switch, is just slightly out of reach. You can access that by going through the opening for the screen. The switches themselves are just two plastic allen key screws which turn in order to adjust drop or height. If powered, the motor actually edges forward in the direction it was travelling only, so that you can set the drop perfectly, if you set it to too high to start off with on purpose. I cannot understand why they would not include simple instructions on adjusting this with the screen?!
    Anyway, I've also had complete success with the 12v trigger. I bought a very small crossover relay from Farnell which I've replaced the rocker switch with. You simply leave the relay powered to make the up connection all of the time there is no 12v trigger. It flips over making the down connection and breaking the up connection whenever there is a trigger signal present from the amp. Now, when I switch to an amp source that I've set up to supply the trigger e.g. DVD/Laser, down comes the screen :) Switch to another source or switch the amp off and up goes the screen. The limit switches ensure that the power gets cut at maximum travel in either direction. I also bought a few metres of fine coax and a 3.5mm jack plug at the same time, so that I have a neat connection from the 12v trigger on the amp to the rocker switch housing. The housing now holds the connection block for all of the wiring, so everything is hidden away, neat and tidy. Not bad for about £8.

    Works perfectly and your absolutely right about the noise. Its so cool to have your screen roll up and down automatically that I'll live with slight noise :cool:
    BTW - Your dealing with mains voltage with the screen, so don't mess about if your not confident with what your doing.
    For those that are interested the Farnell code for the relay is 4148393 and it costs £2.55. I'm sure Maplin will do something similar, but I have found that the free next day shipping on orders right up to 8pm at night at Farnell online to be unbeatable.

    Happy motoring :smashin:
     
  5. WeirdFish

    WeirdFish
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    Good when a plan comes together huh.

    My automatic method is to tell the wife to lower the screen, but as expected this is not very reliable. In fact it hasnt worked yet and I have received injuries trying :D
     

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