Film-Tech Forum ARCHIVE: Sound Warble Simplex XL

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Posted by Don Hallmark (Member # 3450) on 11-17-2005, 10:31 PM:

I have a bad warble that is really noticeable in all music. This projector has set for several years but I just replaced all of the bearing in the sound head and on the drum. Could the motor cause that and not show up in the picture? I am a newbie again so I am stumped.

[ 11-18-2005, 06:14 AM: Message edited by: Brad Miller ]

Posted by Mark Gulbrandsen (Member # 72) on 11-17-2005, 11:07 PM:

Hopefully you utilized bearings on the sound drum that don't have any sort of seal on them. Any seal will put enopugh drag on the scanning drum so that it never quite reaches free wheeling film speed. Other than than the drum having some sort of drag on it from another place like the flywheel side there is little that would cause it. I assume you also overhauled the lateral guide roller as well and that it spins very freely..... Everything MUST spin like a top when you hand spin it and continue spinning. The sound drum should free spin for a minimum of 20 to 30 seconds after applied hand motion is removed.

As for bearings on the sprocket shaft... I highly reccomend bearings with rubber seals for longer life. Keeps things outside out of the bearing out of it and whats inside it in place!!

Could vaguely be belts that are excessively tight but if yours are the round tooth version that is highly unlikely. There should be about 1/4" to 3/8" slack on them.. at least.

Mark

Posted by Gordon McLeod (Member # 33) on 11-18-2005, 12:17 AM:

I think you may have a flat spot on the lateral guide pinch roller
and if it is a XL soundhead then it is possible that the inner and outer flywheel have been dinged and touching

Posted by Monte L Fullmer (Member # 2797) on 11-18-2005, 04:52 AM:

Go back to your post and remove your email address - this is a no-no here. Need to read the rules.
Yep, flat spot on the lateral roller does this "bird warble" quite often.

-Monte

Posted by Bill Enos (Member # 440) on 11-18-2005, 07:34 AM:

Could be as simple as something stuck to the drum, some sticky tape residue will do it.

Posted by Mark Gulbrandsen (Member # 72) on 11-18-2005, 07:41 AM:

Monte, They should make you a moderator [evil]

!

Also check that the rubber roller isn't split. Hard to see sometimes but this happens on older units...

Mark

Posted by Louis Bornwasser (Member # 3063) on 11-18-2005, 09:08 AM:

Nothing to add except drum bearings are available that are covered, but that do not drag like rubber seals. They are somewhat hard to find. The cover stope about 0.001 from touching; keeps out dirt, but does not drag. louis

Posted by Steve Guttag (Member # 268) on 11-18-2005, 09:08 AM:

There have also been instances where the viscous oil within the flywheel has leaked out (or been removed) and thus the drum never couples to the flywheel. Everythink spins but it isn't really coupled...see if the drum is spinning at the same speed as the flywheel.

Posted by Barry Hans (Member # 477) on 11-18-2005, 10:35 AM:

Also check the lateral guide roller upper bracket for a hairline crack that can cause the lgr to "bounce" just enough to cause a problem.

Posted by Don Hallmark (Member # 3450) on 11-18-2005, 11:08 AM:

Thanks for all of the help. I replaced the rubber roller in the lateral guide assembly. All of the bearings are Simplex replacements. Thanks again,

Posted by Bob Koch (Member # 1062) on 11-18-2005, 12:56 PM:

Check the concealed spring between the upper and lower sections of the guide. The intended tension is probably missing. You have to seperate the two sections, pull out the coil spring and stretch it. Don`t lose the ball.

Posted by Louis Bornwasser (Member # 3063) on 11-18-2005, 01:01 PM:

Barry: crack in upper bracket: we "stripped" 50 of these and found the crack in 39. Louis

Posted by Rick Raskin (Member # 1561) on 11-18-2005, 01:10 PM:

Not to sound condescending, but sometimes the most simple thing can be the cause. You are backing off only 2 perfs at the hold-back sprocket? More than that could cause a free loop around the sound drum.

Posted by Don Hallmark (Member # 3450) on 11-18-2005, 03:16 PM:

Yes I am backing off 2 perfs at the hold back sprocket. When it is done at 1 perf you can hear the warble really bad. Just barely at 2 perfs. When I don't load the machine it gets to tight it seems. Thanks for the help.

Posted by Rick Raskin (Member # 1561) on 11-18-2005, 03:28 PM:

As mentioned earlier, it appears the sound drum may be binding and not spinning freely. That would be consistent when you run with a 1-perf back-off. It forces a tighter loop. Also, see Steve Guttag's post above.

Posted by Mark Gulbrandsen (Member # 72) on 11-18-2005, 06:58 PM:

quote: Louis Bornwasser
Barry: crack in upper bracket: we "stripped" 50 of these and found the crack in 39. Louis

Louis,

Now you know why I always refer to the Simplex stuff as "Pot Metal Deluxe" cinema equipment. The older X-L head main castings metal quality is right up there with those old lateral guide arms!

We've tried the tight clearance shielded ball berings and out here it doesn't matter much..... its so dry here that the grease always dries out before the bearing has a chance to get dirty. If we could just get new bearings with a tiny bit of very light synthetic grease in them, but alas this has not come to fruition from any of our bearing suppliers.

Mark