Film-Tech Forum ARCHIVE: AW3 creeping at take up

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Posted by Justin Hamaker (Member # 2165) on 04-26-2009, 03:34 AM:

Tonight we discovered that one level of the AW3 at our drive-in is creeping when used for take-up. At the point where it should be stopped when the projector is threaded, it still turns slowly. What are the likely causes for this. I know one is the low pot is set too high on the motor control card.

Posted by Scott Christopher (Member # 834) on 04-26-2009, 04:27 AM:

Align the decks according to the manual. I had this a few times due to the LDR (could not get my low speed). Replacing the LDR solved the problem. There's a tweak guide under the TIPS section I think, that may help.

Posted by Louis Bornwasser (Member # 3063) on 04-26-2009, 09:11 AM:

The tips guide is far better than the manual. The manual assumes (incorrectly) that the mechanical alignment is already correct. Louis

Posted by Steve Guttag (Member # 268) on 04-26-2009, 10:45 AM:

If it has fixed centerfeeds...verify that the payout feed fingers are not binding on the first roller in the centerfeed cluster. In take-up, they swing back in that direction.

Steve

Posted by Ken Lackner (Member # 1002) on 04-26-2009, 05:04 PM:

Forgive the ignorance here, but what is the LDR? I've never heard that term in connection with a Christie platter before.

Posted by Steve Guttag (Member # 268) on 04-26-2009, 05:17 PM:

LDR = Light Dependant Resistor

You would know it as a cdS (Cadnium Sulfide) cell.

Carry on.

Steve

Posted by John Walsh (Member # 168) on 04-26-2009, 05:33 PM:

If no luck, consider the infrad upgrade kit. Trying to get the old PC cards to work with new LED sensors (or the other way) can be, uhm, trying.

Posted by Ken Lackner (Member # 1002) on 04-27-2009, 05:53 AM:

Thanks, Steve.

So, Scott, did you replace just the cell, as in solder a new cell onto the board? Or did you just replace the whole LED/cell assembly?

John: The motor control cards should work just fine with either the visible LED or infrared. At least as far as I know. Now, perhaps if they are *really* old, there was some difference in the circuitry and they need to be replaced with current ones, but I'm not aware of that. The LED card, however, does need to be replaced when upgrading from visible to IR.

Posted by Mark Gulbrandsen (Member # 72) on 04-27-2009, 08:34 AM:

Yea, Christie gave up on the old CDS cells as they became too inconsistant in manufacturing over recent years... some new cells were too far out of range to even work correctly! thats why the IR conversion kit... and it's self calibrating to boot. Also be sure the return cam is not broken. It's a question mark shaped nylon thingy inside the return arm mount. They become very brittle with age.

Mark

Posted by Brad Miller (Member # 2) on 04-27-2009, 03:36 PM:

Without hearing back from Justin, we are all semi-guessing here.

First things first Justin, when you spin the LO pot counter-clockwise on that deck's motor speed control card...does the motor stop? That is always the first thing to check and 99% of the time the problem. Past that it would be a mechanical issue.

BTW Justin, don't rush out and order the new IR "upgrade" kit like Mark is suggesting. I've ranted about this for years. They suck! In fact I had to get Christie to ship out my last couple of AW3 orders with the old visible leds to get the quality level I expect from an AW3 that simply cannot be achieved with the IR kit. The IR kit makes the platter's response very touchy and it likes to sling prints around. While Mark is correct 1 in 50 of the older style will be defective right out of the box...big deal. Swapping them for a replacement only takes 2 minutes.

Posted by John Walsh (Member # 168) on 04-27-2009, 08:49 PM:

Yeah, I was at a theater doing service work and I saw a block of foam with, like 25 of the older CDS cells in it. When I asked the operator what they were for, he said Christie sent them when the theater opened because the ones in the (then) new AW3's didn't work right. He said Christie did bend over backwards to get them running, sending all kinds of parts and a tech to get everything up. I've had CDS sensors work fine, with one type of control card, but poorly with another.

The IR kit includes a replacement filter card. But some people swear using the old one with the IR sensors works better.

So I wouldn't suggest changing out the older sensors right away, but the upgrade may be an option if you can't get them to work.

And an additional suggestion to Justin is to be sure no light is getting in behind the end cap cover.

Posted by Scott Christopher (Member # 834) on 04-28-2009, 05:54 AM:

Ken, I started out with replacing one complete assembly, then just rebuild the faulty ones (always having a rebuilt spare on-hand). I only had 3x AW3 platters, but just soldering a new cell onboard always solved the 'low speed' problem. If you can find a supplier of the cell, it's a fairly cheap way of keeping the platter going without any conversions. I haven't used the IR conversion so I cannot comment on them.