Film-Tech Forum ARCHIVE: Three time's the curse for a Norelco AAII vertical shaft

This is topic Three time's the curse for a Norelco AAII vertical shaft in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by John Walsh (Member # 168) on 06-05-2010, 12:15 AM:

I have a theater with a AAII. About 8 months ago, got a call that it stopped running, turned out to be a stripped fiber shutter gear (the one on the vertical shaft.) Interestingly, it is only stripped about 180deg around. The customer has two gutted spare AAII's so I took the vertical shaft from one of them, installed it in the proj, and it seemed to be running fine. Until about 2 months ago ....

Got a call that the projector wasn't running again. Same problem, stripped fiber shutter gear. This one is stripped 360degs around. Everything seemed to be OK, nothing that would stop the shutter in the shutter area, the gate seemed to not to be interfering or anything. I turn it by hand for a long time looking for problems. The oil pump is working good, the little tubes shooting oil right at the gears, intermittent, etc. So I took the other spare vertical shaft and put it in the projector- I notice this vertical shaft has a brass shutter gear instead a fiber, I figured there must have been an issue at one time and the solution was make to make them out of brass. Check it over again, and it seems OK ... until today.

Projector stopped again. This time it turns out to be the shutter compensator (the big gear assembly that slides up and down on the vertical shaft, it's called a 'fork' in the book.) It's seized on the shaft; the fork won't spin or go up and down. Also, the fiber gear at the bottom of the shaft is stripped in one section only, indicating the motor spun while the shaft was frozen and just ate the gear in that position. All the oil in the projector reservoir is black colored.

OK, so I'm stumped. I don't work on these enough to get really good. Does anyone one have any suggestions?

Some thoughts I wonder but am not sure of:
At this location, the operators 'goose' (turn it on/off/on/off)the projector to run down the film to get the '8 in the gate.' Also, I suspect the operators try to open the gate just when the indicator line lines up to the sprocket, while the projector has almost but not quite stopped.

Posted by Gordon McLeod (Member # 33) on 06-05-2010, 12:23 AM:

Someone tried to open the trap when the machine was running or coasting to a stop

Posted by Randy Bowden (Member # 587) on 06-05-2010, 12:33 AM:

I'm thinking the same thing as Gordon. The AA is built like a tank and it's been a number of years since I've needed to work on one, so I'm having a hard time coming up with any other possible cuases.

Posted by Robert Minichino (Member # 3495) on 06-05-2010, 02:04 AM:

I'll join the chorus, they're opening the gate with the machine still running or coasting. Changing the shutter gear from fiber to brass just moved the damage to a different weak point in the machine. I've just torn mine down and rebuilt them, and the only way I can see that damage happening without opening the gate is if the shutter shaft seizes, and that would be obvious.

Posted by Louis Bornwasser (Member # 3063) on 06-05-2010, 08:52 AM:

Yep, these things run FOREVER if not abused. Therefore, abuse is more than suspected.

We changed to JJ Century when professionalism went out-the-window. Louis

Posted by Michael Hossen (Member # 4274) on 06-05-2010, 09:21 AM:

Some people just don't deserve Norelcos!

Posted by Sean McKinnon (Member # 612) on 06-05-2010, 10:17 AM:

John,

Why don't you install a micro switch that will kill the motor when the gate is opened? I have seen this done at a AAII house with less then professional operators. This will not solve the problem as the machine still needs to coast to a stop but it might help minimize the damage.

Posted by Robert Minichino (Member # 3495) on 06-05-2010, 12:00 PM:

I've considered adding a solenoid to the gate to prevent it from opening until a short delay after the motor stops, just to prevent "money shifts" like this from happening accidentally.

Posted by Sean McKinnon (Member # 612) on 06-05-2010, 12:21 PM:

That's a good idea. Maybe some kind of magnet to keep it closed would work as well.

Posted by Randy Bowden (Member # 587) on 06-05-2010, 12:38 PM:

Next time, bring a cattle prod with you. Maybe that will get the point across.

I used to run the Norelco projectors a the Eastgate here in Portland (largest screen until it closed) I have such fond memories. No D-Cinema presentation could ever bring about that kind of nastalgia.

Posted by Robert Koch (Member # 3728) on 06-05-2010, 02:17 PM:

Get rid of those "hamburgers" in the booth. They can`t be trusted with a wonderful mechanism such as this. The very fact that they inch down with the drive motor makes me cringe. Maybe Louis solution is the best; when you bring clowns like these into the booth "the show is truly over".

Posted by John Walsh (Member # 168) on 06-05-2010, 02:18 PM:

Hi, all; I just wanted to throw this issue out there, in case there's some thing about it I'm completely missing. Just about everything on this machine is expensive, so I'm trying to not overlook anything.

As I dismantle it, I admit I just love the fit and finish of the assemblies. The vertical shaft in a Century seems like a toy by comparison, but even back in the 1960's I bet these projectors were much more expensive than any other.

Sean, there is a shutoff switch on the gate opening lever (and upper loop trip.) I have it set to a hair's-breath on opening. The projector does take about 5 full seconds to wind down though.

Robert, that is an excellent idea, but is probably cost-prohibited.

And of course, I have no control over the operators. Actually I'd like to find some other reason for this, if there is one. I'm wondering why it's happening three times in a short time....

I'll try to take some pictures. I guess there are a lot of techs that have never even seen a AAII, let alone work on one.

Posted by Louis Bornwasser (Member # 3063) on 06-05-2010, 03:54 PM:

I think we've hit the nail on the head. People vs. excellent machine: not going to have a good outcome.

Plenty of JJ's around, if you need 70. Louis

Posted by Mark Gulbrandsen (Member # 72) on 06-05-2010, 07:47 PM:

I've see all of the things you mentioned happen. Some of the things that will kill the fibre shutter gears are: A sudden filum pile up that brings the projector to a sudden stop, repeated on and off power bumps, and motor issues. I have seen the bronze gear do exactly the same thing o don't bet your reputation on it! The last batch of DP-70 rebuilds I did all had SSD variable speed motors on them. We also did an auto rotate to gate open position after the projector ame to a stop. Was pretty slick.

As to the seizing of the gear to the shaft... did you loosen the bearing retainer plate that secures the self aligning center bearing in it's holder when installing thesethree shafts? You absolutely have to do this due to slight machining variances in baring retainers. If you take the plat completely off you will find that the bore on the center bearing boss is considerably larger than the OD of the bearing. If you don't loosen the retainer plate when installing the shaft this can lead to an ever so slight bow in the shaft that will cause the gear to gaul to the shaft either where the gear passes through the shutter compensator bracket or through the gear. Also. an excess of crud on the top of the compensator or gear bore that would cut off the entrance of oil around where the shaft passes thorugh the bores. Akso, note that the verticle shaft hangs by the top bearing and is just radially supported by the other two bearings.

It is virtually impossible to open the gate a properly assembled DP-70 while it is running without lots and lots of intended force. There is a centrifigual plate at the end of the shutter shaft that prevents this. I have only seen one time when a gate was forced open during a coast down and that folded the shutter blade in half and stripped the bronze gear.

Also be sure the oil filter and magnet are clean. Do not use red auto parts store rags to wipe down anything in these projectors! I've seen the filter become completely clogged up in just several running hours! These rags have some sort of loose lint on them and is is nasty stuff.

Added: Also note that the vert. shaft IS NOT HARDENED. This makes for gauling being more of a problem if oil flow is reduced. Also be sure gear mesh is proper. I've seen many many DP-70 with very loose gear mesh.

Yes, I agree. The JJ is a Fisher-Price version of this projector... Just a toy. The Simplex... well... built by Mattel!

(Edited version 1.02)

Mark

Posted by Tony Bandiera Jr (Member # 2365) on 06-08-2010, 02:11 PM:

quote: John Walsh
And of course, I have no control over the operators. Actually I'd like to find some other reason for this, if there is one. I'm wondering why it's happening three times in a short time....

There is no other reason for so many repeated failures in such a short time. 100% operator negligence.

If there were any problems with the projector mechanically that would trigger those failures you would hear it as soon as you started the machine. AA's are so smooth and quiet that any impending issues would be very easy to hear.

Posted by Mark Gulbrandsen (Member # 72) on 06-09-2010, 10:11 AM:

quote: Tony Bandiera Jr
There is no other reason for so many repeated failures in such a short time. 100% operator negligence.

Tony,

Apparently you did not read my post above. There is indeed a possible problem with the way the replacement shafts were installed. Keep in mind that THIS IS NOT A HARDENED SHAFT! I have only met one or two other techs over the years that were aware of the following...

If the bearing retainer plate on the center bearing bracket is not loosened before installing the shaft you can end up with a very slight bow in the shaft. This in turn can lead to galling of the shaft where it passes through the bore of the intermittent drive gear as well as the shutter compensator bores. I've seen this happen several times over the years where the tech was not aware that the bearing bore on the center bearing bracket is over sized to allow for self alignment when mounting the shaft at the top and bottom. It is made this way because there are sometimes slight machining differences in the bearing brackets. Tighten the retainer plate screws back down after the shaft is mounted in the machine. BE sure gear mesh is proper... too loose and you will strip the tops of the teeth right off. Been there seen it happen and over 50 DP-70 rebuilt by yours truly!

All the locations around here that have used DP-70 which accounts for close to 40 screens all bump the motor switch when they thread. This is certainly bad for any projector but doing so isn't going to make the gears fail. These projectors do not jump to speed in a half second... more like 3 to 5 seconds to speed. What can make them fail are nasty on off on off power bumps when the shutter is rotating in excess of 2880 RPM.

Mark

Posted by Bill Enos (Member # 440) on 06-09-2010, 01:57 PM:

Ran one of these things one time for one shift, was told about this issue, no problem, however, it seems to me that prudent engineering would have included some sort of mechanical interlock to prevent gate opening while the machine is in motion because it undoubtedly happens a lot more often than most people think. Centrifugal devices require speed to function but some sort of torque clutch would have worked.

Posted by Tony Bandiera Jr (Member # 2365) on 06-09-2010, 03:11 PM:

quote: Mark Gulbrandsen
Apparently you did not read my post above. There is indeed a possible problem with the way the replacement shafts were installed.

Apparently you did not read all the way through my post Mark.

I did read what you posted, and if the shaft were installed improperly (which I agree with you can happen) then you would most certainly HEAR the improper mesh of the gears. The AA is the most quiet and smooth machine on the market and if any part of the drive train were misaligned, especially with that huge casting acting as a sounding board, you would know right away that something wasn't right.

As an RCA service tech I had about 20 screens of AA's and the ONLY time I ever had to do any major work on any of them was when the operators were being stupid, including bumping the film down with the motor.

And I did indeed discover the retainer plate issue, because my first repair I didn't align it as you posted and found out when I turned the motor on for the test run. [Big Grin]

A quick call to my mentor and he pointed me in the right direction.

Posted by Mark Gulbrandsen (Member # 72) on 06-09-2010, 08:34 PM:

quote: Tony Bandiera Jr
then you would most certainly HEAR the improper mesh of the gears.

Actually I've found that in just about every DP-70 I've rebuilt with used parts as John would have done by transferring shafts over run considerably noisier until the gears have run in for a number of hours... usually about 16 to 18 hours (Can also be true of Simplex X-L's!). However, if you use all new gears they run quiet from the get go. The old gears including the steel gears have wear marks and patterns worn in them and they have to re-seat to the other used gear with different wear patterns before things get down to the normal purr the DP-70 makes. The shutter gear pair in particular can be very noisy, actually making a grumbling sound for quite some time because there is basically no loading between the two and seating or run in takes even longer.

Mark

Posted by Thomas Hauerslev (Member # 566) on 06-10-2010, 02:49 AM:

Time for some history: http://www.in70mm.com/dp70/library/story/index.htm

Posted by Per Hauberg (Member # 529) on 06-10-2010, 03:11 PM:

Hi, Mark

When You are doing the big job on a DP70, with NEW gears.
Do You get those gears still from Münich - or are You able to make them in Your own workshop ? (Read: Do You have to...)
----------
As it have been mentioned several times, DP70 seldom makes mistakes by itself. On my two old things, there are no other emergency autostop than the original one over the upper loop, which I've allways considered to be enough. But once, I've experienced true disaster due to a spool tower suddenly stopped (fuse blown). There is no electrical connection between the tower and the projector, and therefore, of course the DP70 continued to run. Digital sound from penthouse made no fuzz and picture was fine - ergo I sat still in my seat in the auditorium - until the projector could not get rid of more film downwards and it began packing around the intermittent. Polyester film outside, fiber wheel inside. The rest is logic !
Of course, the main dump in this play is me, sitting in the auditorium instead of beside the projector. Whats puzzles me is, that the "rejector plate" (don't know the right english word for it) for me to see was not out of place, but eitherway, there were several meters of film aound the intermittent wheel, and it stood very still, while the inside wheels and the motor went on. I do believe, I've seen it do better. This was really hard packed and difficult to get out.
One new fibre wheel and a replacement (renovated) intermittent unit came out of Münich, the Kinoton-tech was in Denmark the next day as usual, when I have trouble (Bravo !) As John Walsh tells, the fibre wheel was only half-way stripped.
But such external coursed mishaps - and projectionist screwing up - for me are the only ways to stop the worlds very best projector. They are getting old and somewhat quirky, yes. But so am I, and they still do their job every day. Two more months now, and they are fifty ! How many DLPs will live to see that ?

Posted by Mark Gulbrandsen (Member # 72) on 06-10-2010, 05:32 PM:

New gears over here come from Kinoton USA. No problem getting them when needed... which is very rare...

Mark