This is topic Philips FP-20 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by John Prince (Member # 1249) on 05-15-2002, 07:56 AM:
I have a problem with sound on start up. Very distorted but comes clean after trailers/ads. Tensioners appears to be ok and loop is not 'to big'. Anyone experienced this problem before?------------------
Posted by John Moriarty (Member # 1153) on 05-15-2002, 08:21 AM:
We had a lot of problems with one of these not too long ago. Throughout the film we would get an underwater sound effect on the analogue sound. We found that turning down the tension of the take up feed on the tower fixed the sound problem, but this wasn't acceptable because it didn't always take up properly. Eventually we found a loose grub screw connecting the lower constant speed sprocket to the drive, allowing the the sprocket to run unevenly, and tightening it fixed the problem. (It took us a while to find because this had been hidden behind the flywheel that was fitted as part of the reverse scan sound reader).
I'm not sure if this will help, but it is probably worth checking as it won't take too long to do.
John
Posted by Steve Guttag (Member # 268) on 05-15-2002, 11:45 PM:
John,Pull off the flywheel plates...and spin the drum shaft (with the pinch roller raised)...see if the bearings are binding any. With the tiny drum, wow/flutter come in very easily. That is where I would start...then look at the pinch roller.
Steve
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"Old projectionists never die, they just changeover!"
Posted by John Prince (Member # 1249) on 05-16-2002, 03:40 AM:
Gentlemen all,
Your comments are appreciated. I suspected the flywheel might have something to do with the problem, but just checked that the retaining nuts had not worked loose. Also the pich roller had (almost) seized. This was freed but the problem got worse.Some of us are seriously old....but we can still bend down to lace up.
I will let you know what happens.
John
Posted by Pete Naples (Member # 761) on 05-16-2002, 05:49 AM:
How's about lay-on (pinch) roller pressure? I've had this exact problem with an FP20, that turned out to be that somehow the lay-on roller pressure had been reduced, by persons unkown. To set it properly you are supposed to use spring balance, there is a figure in the book. I didn't have either book or spring balance with me so I just turned up the lay-on pressure until the sound was audibly stable.Which drum/lay on roller do you have? If it's the early white plastic coated drum I've often seen problems caused by wear. Replacement with the later metal drum solves it.
Posted by John Prince (Member # 1249) on 05-16-2002, 09:48 AM:
Thank you all for your comments. We discovered 2 problems. The pressure roller was almost seized but not unduely worn and the optical lens neede re-focusing. The last one is a bit obvious when you come to think about it. Now the Dome at Worthing has the best sound for ages!
Posted by Steve Guttag (Member # 268) on 05-16-2002, 09:52 AM:
I didn't say check the flywheel tightness, I said to remove it and check the drum bearings! Kinoton uses a bearing lubricant that can turn into honey and settle in the bottom of the bearings.Though there is a figure listed for the down pressure on the pinch roller, I normally use a loop of film with tone one it and see how long it takes to stablize. I go with the lowest pressure that allows a stable tone in less than 7 seconds (to ensure a flutter free changeover). If you get too much pressure, the film will "squish" out since Kinoton/Norelco use a tilted roller to force the film to the outboard edge of the roller (instead of a spring loaded flange).
Often the pinch roller performs better when using "Cardan" oil (a little viscous)to provide damping.
Again, start with the drum bearings first...get them all nice a free (probably need to be replaced), then get the drum shaft end-play right, then move to the pinch roller.
Steve
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"Old projectionists never die, they just changeover!"