This is topic CP-65/DA20 not falling back to analogue automatically in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Andy Patterson (Member # 6704) on 09-14-2012, 12:50 PM:
 
Hi,

We recently had our two FP20s replaced with a digital projector and a single Century film projector. The wiring from the old Proj. 1 was simply reconnected to the Century, only since the change the Dolby set up will no longer automatically drop back to analogue if the digital sound is interrupted, as it used to.

All of the channels on the CP65 work as usual when selected manually. However if it's on Digital 10 and I block the light from the digital sound head the sound just cuts, and the green 'Digital' LED on the DA20 remains on (where it used to change to the yellow 'Analogue' LED).

I've attached an image as there are a few seemingly home-grown adaptations, the righter-most of which used to turn on or off the function I am enquiring about.

I have checked the multi-pin connector on the back of the DA20 and it is seated correctly, nothing was touched on the sound rack during the install.

Any ideas?

Thanks,

Andy


 

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Posted by Louis Bornwasser (Member # 3063) on 09-14-2012, 02:06 PM:
 
Is the flat control cable plugged in Da20 to CP65?

If so, is the rotary switch on the front right of the DA-20 in the correct position?

My memory of that combination is old, but I think the light on the da20 should change upon reversion. If not, something is wrong (switch) or broken in the DA20. louis
 

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Posted by Sam D. Chavez (Member # 1841) on 09-14-2012, 03:28 PM:
 
If you previously had two projectors you must have had motor sense relays and a changeover device that is no longer needed.

When going down to one projector you need to eliminate projector 2 relay and can jumper out the DA20 db9 pins so the projector is hardwired to proj. one.

This is where I would look first.
 

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Posted by Louis Bornwasser (Member # 3063) on 09-14-2012, 04:02 PM:
 
Good catch, Sam.
 

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Posted by Tony Bandiera Jr (Member # 2365) on 09-14-2012, 05:41 PM:
 
^^^ What Sam said.

Jump pins 1 and 5 of the DB 9 motor start connector together.
 

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Posted by Scott Norwood (Member # 30) on 09-14-2012, 08:16 PM:
 
Why would this matter? The projector 2 relay will (should) never close as long as there is no projector 2, and the projector 1 relay will (should) only close when projector 1 is running, which should work fine. As long as everything is wired correctly, there should be no problem with running one projector only. It's done all the time in booths that have two projectors and a platter.
 

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Posted by Tony Bandiera Jr (Member # 2365) on 09-14-2012, 09:37 PM:
 
Scott, it matters because as stated in the DA-20 manual, If a motor start signal is not applied the DA 20 will never revert to analog because without a motor running it is presumed that an analog signal is not available. Doesn't matter if it is a single or two projector setup.

On two projector setups for changeovers the motor start is also used to start the DA-20 in looking for valid Dolby Digital Data prior to the changeover command.

Jumping the terminal I mentioned forces a "Motor Start 1" at all times. The DA 20, CP500 and some CP 650's ship with a connector and that jumper from the factory.
 

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Posted by Scott Norwood (Member # 30) on 09-15-2012, 02:10 AM:
 

quote: Tony Bandiera Jr

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Scott, it matters because as stated in the DA-20 manual, If a motor start signal is not applied the DA 20 will never revert to analog because without a motor running it is presumed that an analog signal is not available. Doesn't matter if it is a single or two projector setup.

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Right, but as long as the M/S relay is still properly connected to projector 1, this condition will still be satisfied.

Or is the assumption that the installer didn't do this?
 

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Posted by Louis Bornwasser (Member # 3063) on 09-15-2012, 06:47 AM:
 
The digital installers either dont know or dont care.
"Butcher jobs" on the 35mm. Most of the calls I get these days are vandalism on 35 by the "fast install,one foot in the car" digital installers.

btw: So far, I have NEVER seen a CP750 B-chain performed. They claim it isn't needed. Louis
 

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Posted by Steve Guttag (Member # 268) on 09-15-2012, 08:55 AM:
 
Wow Louis! I want to FRAME that post!
 

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Posted by Marco Giustini (Member # 4544) on 09-15-2012, 10:23 AM:
 

quote: Louis Bornwasser

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btw: So far, I have NEVER seen a CP750 B-chain performed. They claim it isn't needed. Louis

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quote: Scott Norwood

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What is the D-cinema equivalent of cat. 151, anyway?

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Ummmmmmm, you do know that CAT 151 is/was a test film designed for subjective testing of center/surround balance, right? You don't use it to set B-chain levels with. In fact NO test film is or was intended for use to set B-Chain levels or EQ..that is what the CAT 85c card and the current processor's built-in pink noise generators are for.

To answer your first part of your post, I don't think ANY technician on here has ever encountered a room where the EQ would stay flat, with the extremely rare exception of a room feeding the output of a CP-750 into the analog inputs of another processor. In fact, the few installs I am familiar with that have both a film processor AND a CP-750, they do the reverse and feed the output of the film processor into the analog inputs of the CP750, as the CP 750's B-Chain facilities are better than most older processors anyways. In those cases the EQ's of the film processor are indeed set flat.

quote:

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btw: So far, I have NEVER seen a CP750 B-chain performed. They claim it isn't needed. Louis

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Whoever "they" are need to be outed on this forum and have their hands and legs broken, then subjected to endless hours of Justin Beiber music played in headphones at 110db (with no EQ) until their ears bleed.
 

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Posted by Scott Norwood (Member # 30) on 09-15-2012, 09:45 PM:
 

quote: Tony Bandiera Jr

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Ummmmmmm, you do know that CAT 151 is/was a test film designed for subjective testing of center/surround balance, right?

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Right. But it's still part of the process, I assume as a sort of sanity check for surround levels. What is the D-cinema equivalent of this?

And I'm not suggesting that leaving the EQ flat is a good thing...just that if an installer is dumb enough to do it, he still needs to set the levels correctly for each channel.
 

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Posted by Tony Bandiera Jr (Member # 2365) on 09-15-2012, 09:51 PM:
 
Well I would disagree with you on the sanity check part as if you do a proper A and B chain CAT 151 is a waste of time.

There is no D-cinema equivalent to 151, and what value would checking only the center and surround have anyways? (Remember that 151 was mainly designed to make sure the CAT150 matrix was working properly.) You need to check ALL of the channels, and Dolby Servers (others most likely do as well) come pre-loaded with channel ID and "check" clips. You use them to make sure all the channels are speaking from the right places and that subjectively the overall tonal balance is the same. But they are NOT used to set levels or EQ.

IMHO, the content for channel and sound checks on the server are the equivalents of the 1011 Channel ID test film, and the output of the server itself is the D-Cinema version of the A chain. In film, level and EQ of the A chain was made adjustable due to the variety of optical reading methods and to account for aging of illumination and/or optical focus drifts. Something D-Cinema doesn't have to deal with.
 

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Posted by Brad Miller (Member # 2) on 09-16-2012, 01:15 AM:
 
So Tony, I'm guessing you're not a Belieber?

For the record, I have never seen a CP750 B-chain NOT performed. Of course in the wrong hands the sound will actually be better by leaving the processor uncalibrated, so maybe that was their thought.
 

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Posted by Sam D. Chavez (Member # 1841) on 09-16-2012, 10:20 AM:
 
Dolby Cat. 151 was created partly to see if the 150 was working properly, partly to account for the different timbre of the shall we say shitty surrounds of the day, vs. the output of A4's.

Mostly though it was to convince cinema staff to run some sane surround level.
 

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Posted by Tony Bandiera Jr (Member # 2365) on 09-16-2012, 05:44 PM:
 

quote: Brad Miller

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So Tony, I'm guessing you're not a Belieber? :Razz:

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Don't care for his music but I wouldn't kick him out of my bed. As our good late friend Phil would say, Hubba-Hubba.

Sam, Yeah I remember the early days of surrounds....the local AMC theatre had 6x9 two-way car speakers built into homemade enclosures in all it's Dolby Stereo auditoria.
 

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Posted by Andy Patterson (Member # 6704) on 09-17-2012, 06:27 AM:
 
Thank you for your help, fixed it with a paper clip!

Andy
 

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