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Topic: Christie's Basement Reader

Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 03-10-2002 03:47 PM

I am having a major problem with this. I still have three houses running a high error rate to the point where the CP-500 defaults from SRD to SRA. The tech came up to the theater while I was at Sho-West and condemned the scanner drum bearings.

At the end of the show, I gave each scanner drum a spin with my fingers, and they were smooth as silk on rundown with no bearing roughness detected in all three houses. However, while the film was running and the scanners were up to speed, I touched the lateral guide roller I did detect a harsh roughness. But yet, this roughness was not apparent when I lifted the guide roller and gave it a spin with my fingers.

Is it possible I have some belts going South in the projector? I did detect what I thought was some uneven speed present in the lateral guide area as the projector was running. The Dash pots are working properly, and I am going to call in another tech to see if there is enough video acquisition signal present.

Any other suggestions?

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 03-10-2002 04:03 PM

Get a scope and the reader alignment program out for a full calibration. Make sure you are using a good "average" test loop, as just running an SRD track off of a "Dolby Tone" loop is never very accurate. Instead splice together a bunch of trailers in 10 foot lengths and watch the readings on the laptop in a known good house (lateral alignment, azimuth, etc) and try to select a piece from that roll to serve as a good loop to calibrate from. For some reason, I was only able to achieve zeros on the error count when magnification was set to 101-102% on the Christie basement reader.

Do the Joe test and put a nut on top of the led bracket for the upper lateral guide arm to rest on. Does that help the readings? If so check your sound drum bearings. If not, check your belts. Too loose is just as bad as too tight.

If these are older basement readers that do not have the "double d" logo on them, check to see if the slit is crooked on the led. If so, throw them away and get the new ones.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 03-10-2002 04:38 PM

Paul, With your two fingers pinch the two lateral guide rollers together and you'll most likely feel the cogging actuion of the belts that I have been talking about. This does feel like a roughness and gets worse as you pinch them together harder. I'd let off on the belt tension adjustment just to before the belt will actually slip when you turn over the the mechanism with the inching knob. This is how they usually come set from the factory, sorta loose. Also check the surface of each CCD chip to be sure it has not gotten dusty. Clean them up and re-assemble, then set them up with a scope and DRAS running at the same time to get it finely tweeked. This should get them playing again. Also while you're at it check the LED current level as well. Perhaps your LED's have faded out to the point that they are just barely bright enough. Had this prob on several CAT 70's a few weeks ago. Some prints would play and some wouldn't. Also try threading them loose instead of tight. For whatever reason sometmes they play ok this way.
Mark @ GTS

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 03-10-2002 05:21 PM

Mark, indeed, they do as you mentioned when I pinch the two together.

Brad, I will check what those things have. I think they are the older readers, as I do not recall having seen Double D on them.

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