This is topic Sprocket Problems on cat 700 reader. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Tom Kroening (Member # 201) on 08-17-2000, 05:19 PM:
On one of the dolby readers we have makes a crunching noise. I'm thinking it could have a few hooked teeth on the sprocket. I've read that you can just take the sprocket off and turn it around. Is this recommended for the reader? Any suggestions would be helpful.
Posted by Gordon McLeod (Member # 33) on 08-17-2000, 05:27 PM:
I haven't seen a penthouse reader ever get hooked teeth
If it does you should be able to see it with a magnifier
Posted by Mark Gulbrandsen (Member # 72) on 08-17-2000, 05:53 PM:
Tom,
Check where the curley spring(actually an RCA soundhead spring)that locks the pad arms closed goes into the main casting. They sometimes oxidize in the hole. I don't know if its the dissimilar metals or if the alumnium casting just oxidizes. This happened allot to me back in the Chicago area, and with the salty air in your area it could also happen. After cleaning out the hole put a dot of super lube on the end of the spring to help keep it from oxidizing again. This could be the cause, especially if the pad arms are stiff to open or close. Also check for 2 film thicknesses of clearance between the pad roller and the sprocket. If the clearance is too small it can make noise when running film through.
Finally, Is it possible that your film is damaged?
Mark
Posted by John Walsh (Member # 168) on 08-18-2000, 11:06 AM:
We had something similar. I notice it comes and goes with different film stocks. But it wasn't real loud or anything.One time, someone removed that first 35/70mm width roller the film goes around, but forgot to put back the little washer-spring thingy that pushes out the roller.
I find the steel shaft for those rollers seem to loosen up after a while. Finally went around and "Lock-Tite"ed them.
Posted by Tom Kroening (Member # 201) on 08-18-2000, 02:15 PM:
This happens with all films yet doesnt affect the digital reading. I have noticed that after we moved a print from this projector to a different one, it seemed to start sheding its SDDS track (which could be unrelated but its a possibility that it is related). And also I havn't seen a hooked sprocket on a reader either, but the people that work at this theatre keep on threading the readers WAY too tight, like you could fit two fingers between the two tension rollers.
Posted by Tom Kroening (Member # 201) on 08-18-2000, 02:17 PM:
Also, with the springs. When i first got to this theatre I cleaned most of them off right away (you could hardly open any of the clips!). BTW if you hold the film between your fingers and put tension on it the noise stops.
Posted by Brad Miller (Member # 2) on 08-18-2000, 03:52 PM:
Have you checked the physical alignment of the film entering and exiting the sprocket?
Posted by Tom Kroening (Member # 201) on 08-18-2000, 08:34 PM:
looks dead on to me, I will check it again though. It comes right out the bottom of a DTS head right into the reader.
Posted by Brad Miller (Member # 2) on 08-19-2000, 01:44 AM:
I meant from the guide roller on the cat 700 into the sprocket as well as the first guide roller coming off of the sprocket. 
I'm not putting much of a bet that is your problem, but I did see that once before.