This is topic Ballantyne gate problems in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Charles Lubner (Member # 157) on 12-23-2000, 03:03 PM:
I'm using a Pro35 that has a serious gate problem. Everytime a splice runs through it, it causes the top loop to get smaller. By the middle of a film, the film loses all its loop and the tension is incredible, making for some horrible noises. Ideas? Suggestions? Thanks!
Posted by Paul G. Thompson (Member # 655) on 12-23-2000, 04:34 PM:
Charles, I presume your splices done correctly. Does the machine stay in frame as the loop shrinks? If the upper loop is getting smaller, you might want to check the pad rollers on the upper feed sprocket for "goose egging", for a lack of a better term. Also, check to make sure that he pad roller adjustment is correct. Some people use two thicknesses, as the manual points out, some people use only one film thickness. I recommend two thicknesses. Be sure the adjustment is the same on both rollers. Also check the sprocket for hooking, broken teeth, etc. If you have to replace the sprocket, use a VKF. 
If the loop is getting bigger, it sounds as though the gate adjustment screw 2784-R backed itself out quite a bit. That will also give an obnoxious picture jump on the screen.
That is the accentric screw that allows fore and aft adjustment of the casting 10535. If that adjustment appears to be ok, someone may have dropped the film gate and pressure pad assy on the deck and sprung the lower portion that holds the intermittent sprocket shoe. If this is the case, the sprocket shoe may not be making contact (or very little) with the film when the gate is closed. It can be restored back to its orginal position very easily. However, be careful. If you "restore" it too much, that lower portion of that assy could come in contact with the film, and seriously scratch the film stock. Seen this happen a bunch of times, unfortunately. 
Posted by David Kilderry (Member # 142) on 12-23-2000, 09:44 PM:
Paul is asking the right question, Charles. Is the film jumping out of frame? If yes the problem is at the intermittent if no it is the upper feed sproket. Check the tension on the pad roller too at the feed sproket in addition to the adjustment of two film thicknesses. Also check the lateral alignment, all of these would need to be pretty well out of spec for your film to jump sprokets in the gate.David
Posted by Randy Stankey (Member # 64) on 12-23-2000, 11:11 PM:
I have to agree with the experts here.If you're blowing a loop it's likely because the film is slipping off a sprocket. Checking all the pad rollers is the first step I'd recommend. (But Paul recommended it first!)
Second thing I'd think of is whether or not there are any busted-out sprocket holes in the film. Like Paul asked, "Is it staying in frame?" That's a major telltale.
Other thing I'd ask is, "Does it always happen at the same place in the film?" If so, then it's almost definately due to busted-out sprocket holes.
Posted by Charles Lubner (Member # 157) on 12-24-2000, 12:01 AM:
Thanks for the help guys. It happens on any film, I ran a test loop and it did the same thing. Every time the splice ran through, it slipped. I compared the gate to another machine, and when I close it on this one, it has quite large gap between the sleds and the back of the gate. I'm not a regular operator at this theatre, but I know how to and have a fair knowledge of technical stuff. Last night I stayed extra late and replaced their burnt out framing lights. They didn't even know how to take off the casing to the shutter!! I will follow all your suggestions and hopefully the problem will go away.
Thanks Again, Merry Christmas!
Posted by Darryl Spicer (Member # 711) on 12-24-2000, 02:31 AM:
The good ol' pro 35's. I remember them well. I worked with them for seven years. If you are loosing the top loop I would eliminate anything dealing with the film sticking in the gate or slipping on the intermittent sprocket. This usualy causes the bottom loop to get small and the top loop to get big. I would take the advice of Paul and check that top feed sprocket. Check for propper distance between the pad rollers and sprocket. Also check the splice itself. Make sure the splicer is cutting the tape corectly. There should be no overlaps of tape on either edge of the film. This can cause the pad roller to jump posably causing the film to slip a sprocket. And can cause other problems as well.
Posted by Pat Moore (Member # 380) on 12-24-2000, 09:53 AM:
Hi; As a Ballantyne guy I have to look hard at that upper sprocket and pad adjustment as well. That's the only thing that can make that upper loop get smaller. Logical choice, as it sounds like there's not been too much maintenance applied here.Depending on the generation of PRO35, that pad assembly can be a bit tedious to adjust. The early version had too many adjustments.Assuming the film is properly guided into the projector from the top, adjust to two film-thicknesses or a little more -- never less. Are the sprocket teeth hooked or worn abnormally?
Merry Christmas!
Pat
Posted by Paul G. Thompson (Member # 655) on 12-24-2000, 12:16 PM:
Gentlemen, I just received a report in one of our theaters where a splices were derailing the film on the upper feed sprocket. In this case, it was just a loose pad roller shaft, along with an alignment problem from the guidance hardware to the sprocket itself. Merry Christmas to all.
Paul
Posted by Charles Lubner (Member # 157) on 12-26-2000, 10:31 PM:
Thanks for all the help everyone! It took me about 1 minute to fix the problem after I knew what I was looking for. The pad roller had slipped down a bit and all I had to do was move it up and tighten the allen screw. I ran a test loop and the loop stayed perfectly. Now if I could just get rid of that nasty focus jump when the splice runs through the gate...... :-)
Posted by Paul G. Thompson (Member # 655) on 12-26-2000, 11:31 PM:
Charles, when the splices are made, is someone taping over someone else's tape? If so, that can cause a problem. When the film is assembled, peel off the tape that was left behind from a prevoius splice job. If you can't peel it off, just cut out the frame. Be sure to tape both sides of the new splice to prevent it from hinging. Also make sure the tape does not hang over the edge of the film after the splice is made. If it does, Use a pair of scissors to trim it, and get some new parts for your splicer. Also, make sure the register plate on the splicer is not worn out. If the splices are otherwise perfect, then there could be a mis-alignment of the studio guides (P/N 3521, 3553, and 2832), and/or the lateral stabilizer plate,(P/N 3522). I think most of the Marcus's Ballentines have that style gate that use the parts I mentioned. The lateral stabilizer plate has to be removed and cleaned from time to time because of crud build-up which would prevent that plate from seating squarely. Also, there could be a gross mis-alignment of the entire gate assy with reference to the intermittant sprocket. Ballentine makes gate gages to check that. Your service engineer is probably equipped with those. Last but not least, your film trap tension may not be properly set. The Pro-35 manual explains very nicely how to adjust that. Pat Moore, did I leave anything out?
Posted by Pat Moore (Member # 380) on 12-27-2000, 06:40 AM:
Sounds like all is covered, Paul. If it's still losing that upper loop, though, that upper pad roller is the likely culprit.
Posted by Paul G. Thompson (Member # 655) on 12-27-2000, 07:47 PM:
Pat, he got the loop problem fixed. Loose pad roller bracket was the cause. He has focus "pops" when splices go through now.