Film-Tech Forum ARCHIVE: Dolby CP200 Format Change Timeout

This is topic Dolby CP200 Format Change Timeout in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Daniel Alt (Member # 2303) on 08-22-2004, 05:55 PM:

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.

Posted by Steve Guttag (Member # 268) on 08-22-2004, 07:44 PM:

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

Posted by Rick Long (Member # 213) on 08-22-2004, 09:16 PM:

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.

Posted by Steve Kraus (Member # 476) on 08-22-2004, 09:37 PM:

LOL...replacing the aging Ultra Stereo with the processor that never ages. [Big Grin]

Posted by Daniel Alt (Member # 2303) on 08-23-2004, 07:12 PM:

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!)

Posted by Rick Long (Member # 213) on 08-24-2004, 08:16 PM:

>>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.

Posted by Daniel Alt (Member # 2303) on 08-25-2004, 08:19 AM:

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?

Posted by Rick Long (Member # 213) on 08-25-2004, 06:21 PM:

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?