Stewart screen retraction problem - AVS Forum
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post #1 of 6 Old 03-05-2001, 05:16 AM - Thread Starter
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Hi, I've got a Stewart Electronic Studiotec 130 with a 12v trigger connected to my Seleco SVP400 projector, no problem on the trigger lowering the screen when the projector fires up but when the projector is shutdown, the screen does not retract.

It does retract if you apply a little vertical pressure to the base of the screen, anybody any ideas why it doesn't retract properly? Will this be causing any stress to the motor when it is not retracting?

It is just a little frustrating and inconvenient, but other than that it's fantastic!!

Thanks, rgds
Steve
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post #2 of 6 Old 03-05-2001, 11:09 AM
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Dear Steve,
This is going to take some trouble shooting as the problem you state is just the opposite of of a normal screen trigger problem.
A few more questions. Is this a new unit? Was it working fine after it was first installed and the problem just recently started?
1. The first action is to unplug the screen trigger cable from the projector
when the screen is in the down position. This way we can check for any stray voltage that may be coming out of the projector trigger output. If the screen retracts when you unplug the cable then let us know so we can recommend an alternate trigger method.
2. Since the screen descends when the projector is turned on, but needs a push start to get it to retract, this may indicate that the screen motor is not getting the proper minimum voltage that is required for normal operation. Check your house power at the junction box where the screen is wired. Since you are in the UK you need to have a 220/240 volts at the screen junction box.
3. If you purchased a used unit and it was previous used with a Sony projector the trigger output would be just above 5 volts. This would not be computable with the 12 volt Seleco trigger.
Please advise.
Regards,
Don

[This message has been edited by Don Stewart (edited 03-05-2001).]
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post #3 of 6 Old 03-06-2001, 02:26 AM - Thread Starter
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Thanks for the reply Don, to answer your questions in sequence:

The unit is relatively new, unfortunately I bought it in November and exported it from the US. When it was being installed it worked spasmodically however as it was a major task installing it to de-install it and return it as faulty was not really viable (besides it does work it's just a minor inconvenience) It still retracts (very) occasionally on its own.

I will not be able to unplug the trigger cable until this evening so I wont be able to let you know until tomorrow whether the screen retracts.

As I exported the screen from the US it has a US power supply. This is connected to a 5amp 220/110 transformer to give the correct voltage. I've actually tried 2 transformers, a 3amp and the existing 5amp so I would expect the power to be ok.

I'll post again following the removal of the trigger cable.

Thanks,
Rgds
Steve

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post #4 of 6 Old 03-06-2001, 07:11 PM
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[This message has been edited by Don Stewart (edited 03-06-2001).]

[This message has been edited by Don Stewart (edited 03-06-2001).]
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post #5 of 6 Old 03-06-2001, 07:22 PM
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I am having a problem with my computer's internal clipboard so please disregard this post and the one above. Steve... please read the post below.
Thanks for the patience.


[This message has been edited by Don Stewart (edited 03-06-2001).]

[This message has been edited by Don Stewart (edited 03-07-2001).]
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post #6 of 6 Old 03-07-2001, 05:03 PM
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Dear Steve,
With the info that you gave on your second post I can now pinpoint why your screen will not retract without giving it a little manual push. You are using an external step down transformer (220/110 volt) that is rated at 5 amps. The motor has a starting capacitor that can spike to 10 amps when ac power is first applied. That's why your screen will come down but when the motor is under load it won't retract. When you help get it started with your hand you are taking the place of the starter. You should replace the existing transformer with a 10 amp one. Over a period of time your screen motor could be damaged if you continue to use the 5 amp transformer.
Regards,
Don
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