Film-Tech Forum ARCHIVE: Dolby CP500 problem

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Posted by Cory Isemann (Member # 2517) on 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.

Posted by Pete Naples (Member # 761) on 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.

Posted by Rick Long (Member # 213) on 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.

Posted by Steve Kraus (Member # 476) on 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.

Posted by Rick Long (Member # 213) on 08-02-2004, 08:57 PM:

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

Posted by Mark Gulbrandsen (Member # 72) on 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 ]

Posted by Ken Lackner (Member # 1002) on 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?

Posted by Daryl C. W. O'Shea (Member # 1303) on 08-02-2004, 10:26 PM:

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

Posted by Scott Norwood (Member # 30) on 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.

Posted by Daryl C. W. O'Shea (Member # 1303) on 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.

Posted by Ken Lackner (Member # 1002) on 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.

Posted by Mark Gulbrandsen (Member # 72) on 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

Posted by Tony Bandiera Jr (Member # 2365) on 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]

Posted by Daryl C. W. O'Shea (Member # 1303) on 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.

Posted by Pete Naples (Member # 761) on 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!

Posted by Mark Gulbrandsen (Member # 72) on 08-03-2004, 07:35 AM:

I've had them apart. They're not that bad to work on. I used to repair 35mm cameras so perhaps thats why it doesn't seem so bad to me to work on it.

I totally agree with Tony on the UPS issue with the 500. I've done this to quite a few of them. We had one batch of 8 in Oregon that kept loosing the settings. Even Dolby reccomended the UPS's and leaving them on all the time in this particuluar case.

Mark @ CLACO

Posted by Cory Isemann (Member # 2517) on 08-03-2004, 05:35 PM:

quote:
(Tony)_ 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!!

If it were only that easy. We have 20 screens, and the company still won't spring to have the roof repaired, much less spend a few bucks to back up the soundracks. Also, we have been out of 2000 watt xenons for 3 months now, some are pushing 5000 hours.

Posted by Mark Gulbrandsen (Member # 72) on 08-03-2004, 06:47 PM:

"Also, we have been out of 2000 watt xenons for 3 months now, some are pushing 5000 hours."
________________________________________________________________

I replaced two in Elko last week that were over 14,000 hours, the other two were over 9,000. The two that were over 14,000 were the original lamps installed when the theatre opened up 6 years ago! The light was still pretty good and the lamps were stable. That says alot for both Christie lamps and Christie SLC consoles.... and rotating the lamps as specified. Its not my choice to run them that long but who can complain with service like that.

Mark @ CLACO

Posted by Steve Kraus (Member # 476) on 08-03-2004, 08:22 PM:

Mark, weren't there any brothels that needed your services? [Eek!]

Posted by Mark Gulbrandsen (Member # 72) on 08-03-2004, 09:03 PM:

None in Elko, its a nice family town. There are 4 in Winnemucca and one in Wells.

http://www.winnemucca.nv.us/winnemucca/preview/sitenav.asp?iTopic=ShowBiz¶m=46

They may have booths there but not the kind that house projectors......

Only Steve would change the subject from CP-500's to brothels.... [Roll Eyes]

Mark

Posted by Tony Bandiera Jr (Member # 2365) on 08-04-2004, 12:37 AM:

quote: Mark Gulbrandsen
Only Steve would change the subject from CP-500's to brothels....

Mark: Why not? I've always referred to the Dolby Processor line as "See Pu..Y" [evil]

Great minds think alike... [beer]

Cory: I understand where you're coming from...but ask in a polite way if management would rather drop $800 (for all your screens) to stop problems or pay a helluva lot more to keep repairing blown processors..bet that door from Dolby is a LOT more than $40!

(Edited to avoid double post..my bad)

Posted by Steve Kraus (Member # 476) on 08-04-2004, 12:41 PM:

Hey, if you're talking about backroads Nevada the things that come to mind are ghost towns (& mines), ghost railroads, and houses of ill repute.

Posted by Mark Gulbrandsen (Member # 72) on 08-04-2004, 05:18 PM:

Here is a listing of all worthwhile ghost towns. You already have the list of houses of ill repute!
http://members.tripod.com/~catmandoo2/listings.html

Mark

Posted by Cory Isemann (Member # 2517) on 08-05-2004, 10:20 AM:

Tony: I might talk to our DM about it. Maybe if I present him with a report and cost breakdown, he might go for it. Slim chance, though.

Posted by Tony Bandiera Jr (Member # 2365) on 08-05-2004, 02:55 PM:

Cory: That's the right approach! [Smile]

Hit them with the numbers and it usually gets you want you want! Try to find out the cost of those doors from Dolby first and see how it compares.

I have found that even the tightest of companies will spend the preventative money if you can show costs side by side.

Keep us posted! And good luck!