Film-Tech Forum ARCHIVE: Dolby cat 699 reader Droping out

This is topic Dolby cat 699 reader Droping out in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=007429

Posted by Donny Miner (Member # 1590) on 09-02-2005, 10:29 PM:

Our Dolby cat. 699 reader is still dropping out after being realigned, a new bulb installed and calibrated to specs. It's reading high 5 and 7's and every few seconds an "f" and then back to 5,6 or a 7. We have a 75w 12v lamp in the unit right now and it should be correct but let me know if its not. I know this is one of Dolby's prototype readers and that they do have problems with high reading rates. Could vibrations from the projector have an effect on the reading and thus making it drop out? Any help with this issue is appreciated... Thanks!

Donny

Posted by Gordon McLeod (Member # 33) on 09-02-2005, 10:47 PM:

Connect a laptop with DRAS10 running and see what the jitter is that will be from the projector

Posted by Mike Babb (Member # 1379) on 09-03-2005, 08:06 AM:

Is the bulb you put in exactly the same as the one you took out? I've seen problems switching brands, and also a 699 takes a different bulb than a 700 I think? Maybe check to make sure all the rollers are spinning cleanly and the arms move cleanly on the shoulder bolts? And no jerkiness with the film feeding out of the platter brain? Like Gordon says, the computer and scope will tell you what you need to know.

Posted by Steve Guttag (Member # 268) on 09-03-2005, 10:06 AM:

Actually, the Cat. 699 should do as well or better than other readers...it was a rather precision piece. Its biggest weakness is the flywheel, which isn't massive enough.

With the film out of the penthouse...give the drum a spin...it should coast for some time...if it quickly comes to rest, then you have something rubbing the flywheel on the back side or you have some bearing problems. This is most likely where your problem lies.

As to the lamp, yes it was a special lamp made by Gilway or some such company...rather pricey too. You should be able to get 4-volts p-p on an Oscope with that.

Another thing to look at with Dras is the "Quick Histogram" (press "H" on the dos version of the program). You should see BOTH peaks clipped off. If you don't see two well formed humps that are clipped off then you have CCD problems or a broken/missing UV filter (strip of glass in the lamp compartment right after the lamp but before the light pipe).

Steve

Posted by Mark Gulbrandsen (Member # 72) on 09-03-2005, 10:18 AM:

Also check the lateral guide roller to see of its edges are worn. A bright shiny side flange in which the hard coat is worn off of is a good visual indication that its time for a new lateral guide roller. If excessively worn it will allow the film to move laterally and then the CCD cameras will not read the entire data area. This can also be seen on both the DRAS (black box) and on the scope as the data envlope is moved too far from its normal position. The past year or so I've had a bunch of cat 700's and 701's that I've had to replace the lateral guide rollers on because they were excessively worn.

Mark

Posted by Donny Miner (Member # 1590) on 09-05-2005, 12:27 AM:

I believe I installed the correct bulb. I made sure it was the same size, volts and watts as the same on I took out. We do have a cat. 700 and they do require a different bulb more like a slide projectors. The 699's are shorter and round at the base. As for the sound drum spinning freely... I believe it does, but I'll double check to make sure. I do not have the software to test the reader, but when the tech was here it did display that it did have vertical jitter. He talked to one of dolby's techs and they said the cause of the problem was from vibrations caused by the projector. He did some tweeking on the unit and said it should be fine but no gaurantee to the problem. I'll go ahead and double check the drum and guide rollers for wear and tear.

Donny

Posted by Brad Miller (Member # 2) on 09-05-2005, 12:38 AM:

It would help to know what model projector you have, as well as platter and if there are any other digital penthouse readers on the machine. For example, an SDDS DRP-2000 can affect tracking on SRD and DTS if mounted on the same machine in a traditional fashion. Also, Christie projectors can have terrible chassis shaking with incorrect belt tension, and an AW3 platter with payout problems can cause a bounce in the film traveling to the projector that can also cause the SRD to drop.

So what do you have?

BTW, I'm with Steve on this. The reader cable comes dangerously close to the flywheel in a cat699 reader and odds are that is the problem. Load up a junk trailer and run it, then when it tails out tell us how many seconds it takes for the flywheel to stop.

Posted by Donny Miner (Member # 1590) on 09-05-2005, 01:24 AM:

Hi Brad... It's a Simplex 35. We only have the one penthouse reader... No other digital reader on the projector. We do have a Christi AW3 for the platter system and it does have a little "bounce" on the payout. And yes the tension spring was removed from the center roller of the brain. I'll run a preview thru and check the drum and I'll let you know what happens...

Donny

Posted by Aaron Sisemore (Member # 145) on 09-05-2005, 02:40 AM:

Here's the projector and reader in question:

-Aaron

Posted by Monte L Fullmer (Member # 2797) on 09-05-2005, 03:00 AM:

I've seen the light (fibre optic) tube being knocked out of alignment from center position to the pickup assembly as well with these older units. Something to check as well?

-Monte

Posted by Brad Miller (Member # 2) on 09-05-2005, 04:01 AM:

Do the two rollers that pinch the film just to the right of the sound drum bounce up and down, or do they stay fairly steady? (Compare it to your cat700.)

Also, let us know how long it takes for the flywheel to stop spinning after a tail out.

Posted by Fabrice Dubourg (Member # 1635) on 09-05-2005, 06:29 AM:

anything on the sound drum ?

Posted by Louis Bornwasser (Member # 3063) on 09-05-2005, 08:51 AM:

As Steve said above, the 699 uses a different bulb than the 700. It is a Gilway bulb, rather pricey. It is common to mix the two bulbs and, as I recall, they are not quite the same.

If you installed a new Gilway and still have incorrect operation, then visually maximize the light by bending (if required) the metal bracket that holds the bulb. This bulb bracket is somewhat touchy. Be sure to consider the angle only seen when you climb up on a chair and look downward.

Remember, this thing once worked...what changed? Alignment? It is remote that the "camera" actually failed. Louis

Posted by Donny Miner (Member # 1590) on 09-05-2005, 02:44 PM:

Ok... It took the flywheel 20 seconds to stop spinning after tail out. So don't think that is the problem. The two rollers seem to stay steady, but if I put my index finger on the two rollers when the film is running thru I can feel a buzz in the two rollers... Could this cause a problem? I aslo checked the the bulb for alignment and does seem straight on with the fiber optics. The CCD glass looks in good condition and is clean. The bulb that was replaced with the Gilway was an Osram one. But the problem started long ago with the Gilway... About a few months ago. Thought replacing it with a new one would help, but no dice. I did check the two roller flanges and they do look wore down and are shinny and the back side of the top roller has a sharp edge to it.

Donny

Posted by Steve Guttag (Member # 268) on 09-05-2005, 03:43 PM:

I would normally say that 20-seconds of spin down is a bit short but on the Cat. 699, the flywheel is aluminum and not very massive...as such that may be correct.

As to the lamp, it should be the Gilway and nothing else. I don't know of any common cross to it. The focus point has to be just right to have the light work with the light pipe. You really need an O'scope with Dras to see what is really going on. Dras will let you see the Histogram, the Oscope will let you see the alignment and jitter (I've found the O'scope does better with jitter than Dras' jitter window).

Posted by Monte L Fullmer (Member # 2797) on 09-06-2005, 12:49 AM:

Okey, new simple question on this topic: When the CAT-700 came out, they went to that more inexpensive bulb and I do believe they went to the brass flywheel. Could a brass flywheel be mounted on a 699, and was there any improvement by going to the inexpensive bulb outside of more economical bulb changouts?

thx-monte

Posted by Brad Miller (Member # 2) on 09-06-2005, 03:59 AM:

The flywheels are not interchangeable. Personally, I've found the 699 tracked best of all the penthouses with the cat700 a very close 2nd.