Film-Tech Forum ARCHIVE: More Christie AW3R problems

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Posted by Michael Rourke (Member # 1142) on 02-15-2003, 03:19 AM:

Ok, I have one platter that won't stop spinning even when the speed arm is at 0 degrees. There is no ambient light leaking onto the cell, the control sensor is brand new and is a green LED. Obviously, the LO pot on the motor control card is all the way down and the resistance at 70 degrees is 100Kohms. I even raised the resistance more and more until the rpm slowed then placed the speed arm back at 0 degrees and the damn thing is spinning faster than before! The filter isn't hanging up on anything and comes to rest at the same position as the other two in the tower. I think I caused the problem because in an attempt to make the prints wrap tighter I replaced the motor control card, LED Power card and Control Sensor assembly, because all the original components were really old. Everything worked fine after I replaced the original components and the problem developed a few days later. I think the problem can be traced back to the motor control card just not having enough travel in the LO pot. Any ideas?

Next, This problem happened at 9:00 last night and I don't know exactly how it happened because I wasn't there. Well, apparently the platter was working fine during thread up then went really fast, made a popping noise (arcing) and died. Then the smell of used fireworks filled their nose. When I came by I sniffed all the cards, the transformer, resistors, the mut selector switch and when I got to the end of the drawbridge door I could smell the problem down in the tower. The only way to access the problem would be through the panel where the motor plug is, I'm assuming that a wire came loose from the socket and arced on something. I'll take a closer look tomorrow, but I wanted to know if there was any kind on fuse or thermal shut off in the wiring that I might miss, the motor control card was old and had no fuses on it so I don't know if there was overcurrent protection anywhere else. Has anyone had to replace the wiring in their tower? Is there a kit to make it easier? Well, any help is appreciated. Thanks, Mike

Posted by Darryl Spicer (Member # 711) on 02-15-2003, 11:55 AM:

if it is the green colored motor it has gone bad. To verify this take a motor from the other platter and put it on this one. If the turning stops replace the motor. I have seen this happen before.

Posted by Jon Bartow (Member # 241) on 02-15-2003, 09:45 PM:

Michael,
I'll lay 10:1 odds that you haven't cleaned out the carbon dust from the base of your motors in a long time. Take the motor off of the platter (this applies to both the old green motors and the newer black ones) and remove the bottom cap of the motor.
To do this remove the brush caps then the brushes then the bottom cap. Use a really good vacuum to suck up most of the dust then a blast of compressed air to get the last little bit out. Then take a look at the plastic area around the the brush mounts. There will probably be a large burnt area. Scrape out the burnt material with a flat screwdriver or other device. Use a multimeter set for continuity to check for conductivity between the brush mounts and the case. (There shouldn't be any [Big Grin]

) once the burnt material is gone, you should be back in business. just reassemble, being very careful to get all of the washers and the brushes back in exactly as you found them.
What happens is the carbon dust from the brushes builds up in there and eventually gets thick enough to conduct electricity and when it does.. ZZZAAAAPPPP the motor arcs to ground which fuses the carbon dust and creates a resistor directly to ground which in turn will cause the motor to run non-stop.
If you aren't comfortable doing the motor work yourself, take it to an electric motor shop. But first try another motor with that deck just to make sure you aren't wasting your money.
Jonathan

Posted by Tim Reed (Member # 137) on 02-15-2003, 09:57 PM:

Agreed, it's most likely the motor, but I have seen units with the older MU switches that become shorted due to super high-speed breakdowns. This turns the motor into a generator, and they can generate fairly high voltages, which often shorts a trace across the back of the makeup switch board.

If you find you do have to replace a motor connector on the column, you just have to drill the rivets out (if it's not screwed on) and pop new ones in with the replacement socket.

Posted by Chad Calpito (Member # 1562) on 02-15-2003, 10:01 PM:

I have to agree with Jonathan about the motor problem. I use to operate the Christie AW3R Platters and had to do the same thing, but, always troubleshoot first before spending money or taking apart the motor just to be sure.

Posted by Paul Konen (Member # 41) on 02-16-2003, 01:42 AM:

I have lost two motors, or so I thought, to brush dust buildup inside the base of the motor. You can see the short between the bolt that mounts to the base (right by cord) and the brush holder going up.

I only wish that Christie stocked this part from the motor manufacturer so that a new motor wouldn't have to be purchased.

( Please Bevan !!! [Smile]

)

I will have to try Jon's suggestion about fixing the short.

Posted by Jon Bartow (Member # 241) on 02-16-2003, 04:59 PM:

I've only ever had one motor with burnt carbon in the base that was not salvageable. And that one had shorted out through the windings to the top cap as well. The whole thing was a burnt-up mess.
Paul, the motor in that picture definately looks salvageable. Good luck!
Jonathan

Posted by Michael Rourke (Member # 1142) on 02-16-2003, 05:33 PM:

Thanks guys, I'll try a different motor in the spinner, and replace the socket in the shorted out platter.

I blow out the carbon dust in the platter motors once a year at my 7 screen location, but haven't had a chance to do so at the 4 screen I work at where it has probably never been done.

Incedently, do you guys have a part number for the motor brushes? They should have a lead with a spade terminal on them, not a lead connected to a spring which is what I get when I tried to order new brushes. The motors I have all have a coil spring to the left of the brush holder that push the brush against the commutator.

Posted by Ray Brown (Member # 1449) on 02-16-2003, 11:25 PM:

quote:
Incedently, do you guys have a part number for the motor brushes?

Motor Brush Part#: 599000-089

Probably wouldn't hurt to order extra springs while you are at it. I didn't have one quite in place a while back and it shot out and flew around the booth. Had a hell of a time finding it.

Brush spring Part#: 599000-091

Looks like both come in a minumum quanity of 6.

Posted by Michael Rourke (Member # 1142) on 02-17-2003, 01:55 AM:

Update: Okay I took the motor from the shorted out platter and plugged it into the spinner and it blew the fuse on the motor control card. So now I know that motor has a short, but since the card it happened to originally was an older card without fuses I wonder what the extent of the damage was. Like I said before, the card didn't smell like ozone, the wiring in the tower did, so I fear the worst. I guess I will order a couple new motors and make sure to clean out the others before more problems develop. Thanks for all your responses, especially the visual aids.

Posted by Michael Rourke (Member # 1142) on 02-28-2003, 03:50 AM:

Update: I took a motor off of a different platter on the same tower and the spinning at 0 degrees persisted. I tried several different motor control cards to no avail, then I replaced the brand new control sensor assembly with an even newer one and it ceased spinning at the rest position; however, the slowest I can get it to turn on 20 degrees is about 7 rpm and that's with the resistance set for 100Kohms at 70 degrees. The only component I have never replaced are those resistors on the drawbridge door, could those be giving me problems? Remember these platters have given me nothing but grief, they wrap prints up like Jell-O and then when I do something nice and replace the old components they just stop working all together. Would running the platters with 200Kohms resistance reduce the life on the LED card or control sensor?

I have tried timing them the way I was taught (the way the manual says) and I have tried Brad's method but neither give me smooth platter pay out and all prints wind up loose. It isn't film damage either, because I can run these prints on the platters at my 7 plex and they are like giant frisbees. When I time them for 20rpm at 70 degrees the max speed is 34 rpm, that's quite a punch and it is eating up the drive wheels.

Are there any Christie techs lurking on here? I need help with these bastards. Do older motor control cards not work well with the green LEDs on the control sensor? Will Christie do repair/exchanges with the older(yellow)cards?

Posted by Brad Miller (Member # 2) on 02-28-2003, 09:52 AM:

Please provide the vintage of these machines. If you don't know the manufactured year, we can pinpoint things down with the various upgrades. I think I already know the cause of your problems, but I want to be sure before I recommend anything.

Posted by Mark Gulbrandsen (Member # 72) on 02-28-2003, 07:07 PM:

Michael,
It is very likely that your photo sensor is bad. I had this same problem this week on a service call. The platter would not stop and kept taking in film till......Ouch! Found that the sensor was definately not able to give the correct 70K reading when performing the LED brightness adjustment. Replacing the sensor did the trick. These do fail more often that you might think. Other possible causes are that the feed control fingers are not going all the way counter clockwise because they are bent and hanging up on the sturctural rib that the older payout heads have. Also, there is a white nylon plastic piece in the take up swing arm that dries up and cracks. Move the take up swing arm and see if the feed finger assy goes all the way counter clockwise as it is doing on a good deck. If it doesn't then there's a good chance the nylon piece is broken. If you find that this is the case and its an older platter replace all the white nylon thingys in the entire booth! If you don't replace them all, you will have more re-occurring problems than you know what to do with.
Also, should you run across any motor control cards with 555 I'C's on them, throw thm out and get the current production motor card from your dealer. The 555 I.C. version cards were a disaster!

It is a simple task to rebuild those motors to like new specs. takes less than an hour to do it. Cut the commutator, clean it up, install new bearings that have rubber seals to better keep the carbon dust out, re-assemble it all, and install new brushes. When you re-install the rebuilt motor back on the platter run it in at low speed for a while so the brushes seat properly.

Any local electric motor shop can repair these at minimal price and save you a ton of money. When we rebuild older AW-3's for re-sale the motors always get totally rebuilt.
Mark @ CLACO

Posted by Michael Rourke (Member # 1142) on 03-01-2003, 02:23 AM:

Okay Brad, I don't have a date on the towers, I know all the equipment was bought used. They are pretty beat up, they have V shaped legs, they have the older metal roller brackets with the two tapered white keepers. They have the black rollers (except for ones I have replaced), they have the older (yellow) motor control cards with no fuses, they have the older black motors with the clip on brush caps not the screw on caps.

Recently, I have replaced the take-up springs on all the decks, I also re-set the spring tension on the filters, replaced the bearing on the cam filter, and replaced all the older soft drive wheels. None of these efforts helped the prints to wrap tighter. Bevan dropped me an email and stated that my loose print wraps might be due to static. That might be the case, but the larger, older screen at the 4 plex doesn't have carpet and has no static problems ever and those prints wrap loose. I also have one deck out of 21 at my 7 plex that winds up loose, that can't be static related every time. After I replace all the control sensors and retime all the platters if I still have loose wraps I am going to..........keep trying to make the damn things wrap tighter. This is important to me because these two locations that I run are 4 blocks apart and prints move around on a regular basis.

Can someone please be very specific when they say ground the platter tower? Exactly where is the best place to ground it from and to? And when I level the platter, should I level the feet or skew it until the platters are level?

By the way if any one has one of the newer drive wheels leave a real sticky residue all over the drive hub due to a break or wrap Film Guard will take it right off.

Posted by Brad Miller (Member # 2) on 03-01-2003, 08:09 AM:

During all of this, have you ever replaced any of the cards in the tree (which ones), the filter or the led?

Posted by Mark Gulbrandsen (Member # 72) on 03-01-2003, 10:10 AM:

If you are using Christie drive wheels quit using them and buy your drive wheels from Edw. Wolk. They are a bit larger, made from a different material amd last far far longer than any of the factory drive wheels. Amazingly they are also a bit less expensive.
Mark

Posted by Brad Miller (Member # 2) on 03-01-2003, 10:59 AM:

If Wolk's are larger, than that is bad as it will magnify any "jerkiness" of the platter. Take a look at the 80's drive wheel. it is smaller in diameter and even if the timing is off makes the platter run extremely smooth. I don't know why Christie increased the size in the first place, as that was a foolish move.

I would be happy to send one of the older GOOD drive wheels to Wolk if anyone knows a contact there who could remanufacture those.

Posted by Michael Rourke (Member # 1142) on 03-01-2003, 12:02 PM:

Yes Brad, I have replaced cards in the tree when neccessary. I replaced the LED card on all but one, there are a few decks with new motor control cards, and there are more than a few with new control sensors. I have had platters go down because of the MUT selector switch as well, I have one deck with one of the new fangled MUT switches. I haven't replaced any of the density filters, resistors or the transformer, but everything else has been swapped out at one point or another.

Posted by Brad Miller (Member # 2) on 03-01-2003, 12:25 PM:

Ok, Christie recently changed over to an infared led instead of their "red" and "green" visible leds. If you mix the parts, you will experience EXTREMELY jerky payout and all of the symptoms you are describing. This is most aggravated when you use the new led cards with the new infared leds and don't change out the filter. It's a wonder you can ever make it through a show like that.

If you change out either the led card, or the led, or the light filter, you have to change ALL of them. That's your problem.

Posted by Darryl Spicer (Member # 711) on 03-01-2003, 01:43 PM:

ok this may be an off the wall response here but on the platters at the four screen, do all the decks have nicks in the platter surface. Anything that could catch the edge of the film as it raps back on. In theory this could cause air to become trapped between the layers of film causing the film to be loose.

Posted by Brad Miller (Member # 2) on 03-01-2003, 01:58 PM:

That can certainly cause print throws and jerky payout arm movement, but I think Michael's problem is more in the electronics.

BTW, I just noticed when skimming over your previous posts that you said you were using a green led with the older style led card, and somewhere else you said you had not changed out any filters. With that combination, it sounds like you got a defective led. It happens. Christie has great customer service and should change it right out for you. [thumbsup]

Posted by Mark Gulbrandsen (Member # 72) on 03-01-2003, 03:40 PM:

Brad,
Send a drive wheel to Don Markus at Wolk if you want to, or call and talk to him as to the differences. You might even see him at Showest. Never had much trouble with jerkiness using Wolk drive wheels. I'll get you a measurement on them. Perhaps they're not much larger than the Christie but they seem to wear alot better(Last Longer) than the Christie rollers do.

Seems like Christie just can't leave well enugh alone for some reason. Why on earth would they change to Infrared LED's?? They once had a platter system that worked just peachy keen.

Brad, since you are the AW-3 Guru it would be nice if you made up a chart of the differences of the various versions of them, and also included your reccommended timming methods for them.
Mark

Posted by Brad Miller (Member # 2) on 03-01-2003, 04:18 PM:

I may do that at some point. There are a number of quirks and tips for every piece of equipment out there, but my AW3s run so smooth there is no need to even bother tucking the tail. (That's no exaggeration, we gave up on securing the tail about 3 months ago at two local AW3 theaters. It's just not necessary they run so darn smooth!)

Posted by Michael Rourke (Member # 1142) on 03-02-2003, 02:45 AM:

I very recently got an order of 4 LED cards, and 6 control sensor assemblies, so these LED's should be the ones you are talking about. So I need to change the filter? Crazy. I have pretty erratic payout, but not too bad.

I recently changed a control sensor at my seven plex and had problems timing that platter afterward. So, now anytime I need to replace a control sensor assembly I need to replace the filter too? That's a pain.

Okay I will get a bunch of filters and get to work. Thanks Brad, for letting the cat out of the bag.

Posted by Brad Miller (Member # 2) on 03-02-2003, 02:50 AM:

The new style of filters are linear. (They look like lines that get wider on one end.) You can use these filters with either kind of led, but you HAVE to use them with the new infared leds. You might just want to make a day of it and change them all.

Also, once you install a new led card with the soldered on resistors (instead of the trimpots), you have to upgrade to the new filter and infared leds on all decks if you want things to work properly.

Posted by Michael Rourke (Member # 1142) on 03-02-2003, 03:08 AM:

Thanks again Brad, now go get some sleep!

Here's another update on the deck that stopped altogether, I replaced the motor and the motor socket, The socket had the little ground lead blown off it. After I replaced them the deck would still not work, making me worry that the damage was extensive. I think the problem was originally with the motor, which wrecked the socket, then the MUT selector switch. So, I replaced the switch with a spare and now the deck works again.

[ 03-12-2003, 02:28 AM: Message edited by: Michael Rourke ]