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Topic: Dolby CP500 problem

Cory Isemann
Jedi Master Film Handler

Posts: 500
From: White Plains, MD, USA
Registered: Jun 2004

posted 08-02-2004 01:10 PM

Has anyone ever had a volume knob problem with the CP500? Two of ours in a week and a half have developed an issue where as you turn the knob up (to increase volume) the volume goes down. What gives? Wondering if anyone else has seen this.

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Pete Naples
Phenomenal Film Handler

Posts: 1565
From: Dunfermline, Scotland
Registered: Feb 2001

posted 08-02-2004 02:59 PM

Yup, the knob drives a shaft encoder, which like any other electro-mechanical device has a finite life, sounds like yours has reached the end of that life.

Don't know about the US, but here we tend to replace the entire door assembly, as it's a real b1atch to strip and rebuild... This is assuming you can get the bits from Dolby, which is becoming an issue with the CP500.

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Rick Long
Jedi Master Film Handler

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

posted 08-02-2004 08:47 PM

Replacing the entire door assembly is the way to go here. It helps if the automatic fader-level settings have been programmed (at least on one format) or you may end up dead in the water, unable to put on a show.

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Steve Kraus
Film God

Posts: 4094
From: Chicago, IL, USA
Registered: May 2000

posted 08-02-2004 08:53 PM

Woah...are you guys saying you guys have old CP500 doors piling up that are ok except for the volume shaft encoder? Seems to me they would be worth quite a bit for that display.

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Rick Long
Jedi Master Film Handler

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

posted 08-02-2004 08:57 PM

Over the last couple of years, we have been sending ours to Dolby for repair.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-02-2004 08:59 PM

Have not had one fail out here yet but personally I can't imagine replacing the whole door just for the price of a 40 dollar encoder. Doesn't make any sense to me. That is just an off the shelf encoder, nothing special. Can't find that exact one.... this company will make what ever PPR shaft encoder you need for a resonable price.
http://www.usdigital.com/
Because you have had two fail closly together I would also make sure the data in the 500s hasn't become scrambled for what ever reason before replacing the encoder. This is a much more common problem than encoders failing. Especially in areas that have been though bad electrical storms or might have very dirty power mains. Encoders are super reliable devices and whsn used for this sort or purpose there should not be any large amount of failures of them seen.

Mark

[ 08-02-2004, 11:11 PM: Message edited by: Mark Gulbrandsen ]

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Ken Lackner
Phenomenal Film Handler

Posts: 1907
From: Atlanta, GA, USA
Registered: Sep 2001

posted 08-02-2004 10:19 PM

quote: Rick Long
Replacing the entire door assembly is the way to go here. It helps if the automatic fader-level settings have been programmed (at least on one format) or you may end up dead in the water, unable to put on a show.

Why?

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002

posted 08-02-2004 10:26 PM

Because most customers these days prefer their show to have sound.

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 08-02-2004 10:47 PM

That's why Dolby conveniently included a "bypass" function with a pot on one of the cards to adjust the level. [Smile]

I can't remember offhand, but is it possible that the CP500 will take the same type of remote fader as the CP50/55/65/200 (100k linear potentiometer)? If so, then the quick fix would be to pick one up at Rat Shack, hook it up, and select the remote fader until the main fader is repaired. On the other hand, maybe I'm wrong here and you need the special CP500 remote box instead, in which case you're probably stuck with bypass unless you have one or more of those.

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002

posted 08-02-2004 10:55 PM

Sure, but would you really want to start a show in mono if your customers are expecting more?

I'd rather use a softkey with a preset fader level or start playing musical doors.

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Ken Lackner
Phenomenal Film Handler

Posts: 1907
From: Atlanta, GA, USA
Registered: Sep 2001

posted 08-02-2004 11:07 PM

Let me be a little more specific. Why would you end up with no sound after replacing the fader if you don't have any presets?

Yes, you can use a standard linear pot with the CP500. Good thinking.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-02-2004 11:09 PM

Yes indeed one can hook up a remote 100K linear taper pot to the power/bypass jack on the rear of the 500. To cure your problem and as a temporary fix this is the route I would take provided the encoder is working enough to allow you to do the remote fader select in the menu. You can get a 100K linear taper pot at radio shack for a couple of bucks, hook it up and keep running just as you have been till your tech can replace the encoder. See page 9.3.1 in the 500 installation manual in the F-T manuals pages to see how to set up the remote fader.

Mark @ CLACO

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Tony Bandiera Jr
Film God

Posts: 3067
From: Moreland Idaho
Registered: Apr 2004

posted 08-02-2004 11:44 PM

quote: Mark Gulbrandsen
Because you have had two fail closly together I would also make sure the data in the 500s hasn't become scrambled for what ever reason before replacing the encoder. This is a much more common problem than encoders failing. Especially in areas that have been though bad electrical storms or might have very dirty power mains.

Cory:

Get ye to your nearest major electronics or computer store and pick up some UPS's (APC's BACK-UPS 350ES is great and cheap [$40 or less].) Hook your processors and other digital format systems if any to them and stop a lot of the power problems and other issues. It will save your show and behind one of these days!! [beer]

And to anyone out there with CP-650's and that horribly long boot-up [Mad]

it'll keep your sound from going to bypass with every glitch! [Cool]

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002

posted 08-03-2004 12:00 AM

quote: Ken Lackner
Let me be a little more specific. Why would you end up with no sound after replacing the fader if you don't have any presets?

Rick and I were referring to the time before you can replace the shaft encoder. If it is totally dead you're not going to be able to enable the remote fader, so you'll be stuck with whatever volume your flakey encoder left you at or mono sound in bypass.

Most people don't have spare ones on hand that they can instantly swap out, hence the dead in the water comment.

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Pete Naples
Phenomenal Film Handler

Posts: 1565
From: Dunfermline, Scotland
Registered: Feb 2001

posted 08-03-2004 03:14 AM

Mark, the first time you have to strip down one of those doors to change that $40 encoder, or worse still the screen, you'll see why most people do an exchange door assembly with Dolby!

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