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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Dolby CP200 Format Change Timeout

   
Author Topic: Dolby CP200 Format Change Timeout
Daniel Alt
Expert Film Handler

Posts: 111
From: Lakewood, OH, USA
Registered: Mar 2004


 - posted 08-22-2004 05:55 PM      Profile for Daniel Alt   Email Daniel Alt   Send New Private Message       Edit/Delete Post 
We are currently in the process of installing a CP200 in our theater to replace our aging UltraStereo processor. We've wired a simple pushbutton at each projector to serve as the remote sound change. It works just fine, BUT...

When we select a new format at the front panel of the CP200, if we don't hit the pushbutton (or "GO") within about 90 seconds.. it just changes over anyway. This is NOT our preferred behavior. We've not found anything about this in the manuals we have.

Is there a simple way to shut thie off? Ideally, we'd like to set the new format an arbitrary length of time in advance, and have it just sit there and wait for us to hit the push button for as long as we want it to.

Thanks for any hellp.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11896
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-22-2004 07:44 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
This is not a feature, documented or otherwise of the CP-200. There is something else at work here. Until the "GO" terminal goes high (+15), it will not change. From your description, it almost sounds like you have a capacitor out there that is charging and when it crosses a certain threshold, the format switches.

Again, this is not intrinsic in the CP200 design and I have never had that issue on the many, many, units I've installed and serviced.

Steve

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 08-22-2004 09:16 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
First disconnect any control circuitry and see if the unit does this by itself, or if it is caused by your control circuitry.
If you have the luxury of spare cards, try changing the 156 Projector/Format logic card.

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Steve Kraus
Film God

Posts: 4009
From: Chicago, IL, USA
Registered: May 2000


 - posted 08-22-2004 09:37 PM      Profile for Steve Kraus     Send New Private Message       Edit/Delete Post 
LOL...replacing the aging Ultra Stereo with the processor that never ages. [Big Grin]

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Daniel Alt
Expert Film Handler

Posts: 111
From: Lakewood, OH, USA
Registered: Mar 2004


 - posted 08-23-2004 07:12 PM      Profile for Daniel Alt   Email Daniel Alt   Send New Private Message       Edit/Delete Post 
Thanks for the info.. We go back in to futz with it some more on Tuesday, so I'll keep ya'll posted. We DON'T have any spare cards, so let's hope the problem is an intermittent short somewhere in our remote control logic. Although it seems somewhat high-fallutin' to refer to three pushbuttons and a diode as "logic".

Just to confuse the issue even FURTHER, the exciter lamps for the 35 projectors lost power just before the show, and we didn't notice right away.

Hows that for bad timing? Since we had just installed this new sound processor, when there was no sound for the trailer reel, we assumed it was the processor. So we sit here and frantically press buttons on the CP200, wondering why there's no sound, while an auditorium full of freshmen is making up their own sound effects for the "Shreck 2" trailer. (Honestly, some of them were better than the original)

Grrr.. Fortunately, the feature was in 16. (I never thought I'd hear myself say THAT phrase!)

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 08-24-2004 08:16 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
>>Although it seems somewhat high-fallutin' to refer to three pushbuttons and a diode as "logic".<<

It has been some time since I installed 200's but if I remember correctly, you would need two diodes per pushbutton: one to trigger the projector select, the other to trigger the "GO".

Just makes the logic a little higher-fallutin' is all.

The diode in series with the projector select prevents a logical high from feeding back and triggering the "GO". Like-wise, the diode in series with the "GO" prevents a high feedback to projector select.

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Daniel Alt
Expert Film Handler

Posts: 111
From: Lakewood, OH, USA
Registered: Mar 2004


 - posted 08-25-2004 08:19 AM      Profile for Daniel Alt   Email Daniel Alt   Send New Private Message       Edit/Delete Post 
The ONLY thing we have remotely hooked up is "GO". We have three pushbuttons wired in parallel (one for each of three projectors), with one diode at the end of the chain. So we preselect the next format and projector at the panel, then move to the projector to actually do the changeover.

One diode is all we need for that, right? Since we're not doing remote projector select?

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 08-25-2004 06:21 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
Should work just fine. I don't think the diode is even necessary here.

Still interested what happens if the remote GO line is disconnected from the CP-200. Any chance of this line picking up interference from xenon striking or contactors?

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