Film-Tech Forum ARCHIVE: middle platter won't turn

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Posted by David Bramante (Member # 2436) on 04-15-2011, 06:03 PM:

On an older Christie AW3 the middle platter doesn't spin on feed out or take up. It will spin with the make-up table. Removed the led and reader for inspection. Question: with light on the reader should there be continuity at the plug conection. Do those readers go bad.

Posted by Tony Bandiera Jr (Member # 2365) on 04-15-2011, 11:34 PM:

David, welcome.

A crude test for the led assy is to remove the end cap..if the LED is lit it and the LED card are ok. Shine a flashlight into the end of the arm and if the motor now spins the motor card may be ok.

The LED and CDS cell rarely fail, but it can happen.

If it doesn't spin then two possibilites:

First (and most likely) the motor card is bad...replace it after cleaning the carbon dust out of the motor.

NEVER try to change motor cards with the platter power on, you WILL get a hefty shock from the cards!

Second possibility is that the make-up selector switch is bad.

See the instructions here on F-T for proper timing instructions, which you will need to do after changing the card.

If you have ANY doubts about doing this safely, call in a technician!!

Posted by Monte L Fullmer (Member # 2797) on 04-16-2011, 12:50 AM:

..could be motor brushes since he's mentioned an older AW3 and I bet that middle deck was used for makeups and breakdowns .. - thus that motor has more "mileage" on it than the other two.

..but agree: motor card.

-Monte

Posted by Mark Gulbrandsen (Member # 72) on 04-16-2011, 05:36 AM:

Just swap two of the motor cards around... but remember which one went where so you can put it back after disgnosis! I have found these causes in the order listed to be the most common problems of a dead deck... If the other decks work it's probably not the LED card...

1. Bad motor card
2. Blown fuse on motor card if you have that version of the card. Fuse is 1.4" in diameter and barrel shaped. 2 on each card
3. Bad connection in the motor plug or socket on the column
4. Bad Make up switch assy
5. Completely dead sensor in arm or other mechanical issue with light shutter inside arm
6. Bad motor brushes or other motor issue
7. Molex connector issues inside column on older style platters that have removable electronics

Posted by Tony Bandiera Jr (Member # 2365) on 04-16-2011, 02:27 PM:

Monte and Mark hit on some other good points..but I must caution you AGAINST swapping motor cards!!

Mark, if that middle deck motor is bad (brushes or carbon build-up) then swapping cards can result in ANOTHER blown card and now he'll be down on two decks and officially screwed!!

In short, if my crude tests show the card to be bad then get it looked at by a tech or you'll keep blowing cards and that gets expensive real fast.

Mark, I think you meant 1/4" on those fuses..they are "Pico" fuses and cost a lot..around $5 EACH last time I bought some.
[Eek!]

Posted by Mark Gulbrandsen (Member # 72) on 04-16-2011, 02:55 PM:

Thanks Tony... I typed that at 3am or there abouts. I should have had a 1a in there I suppose. so... 1a. Hook MUT to platter and put center make up switch in and test run motor... if motor runs ok then swap cards. Of course if the motor is really destroyed it can also blow out the MUT speed control as well. It is not fused... so this is where you have to weigh do I blow the motor card fuse or the MUT speed controller...? Motor card fuse = $5.00 and MUT speed controller is about 70 bucks.

Mak

Posted by Tony Bandiera Jr (Member # 2365) on 04-16-2011, 10:54 PM:

No problem sir. [Smile]

I think the motor MIGHT be ok as he said it does work with the MUT...so that probably means bad motor card (or LED card as he didn't specify if the LED is working...)

Yeah a $5 fuse is better than a $70 MUT card..I have two of those actually in my spares.

Posted by Monte L Fullmer (Member # 2797) on 04-17-2011, 11:47 AM:

..and those pico fuses give out a nasty "pop" when they blow!

Posted by David Bramante (Member # 2436) on 04-26-2011, 07:29 PM:

I have swapped the cards and they all seem to work. I checked led and the motor will work fine with mut. I am down to #4 on Mark's list. I plan to borrow a make-up switch and swap that out. Looks like the switches are configured on a card that should swap out.

Posted by David Bramante (Member # 2436) on 05-05-2011, 11:16 AM:

It was a bad make-up switch. Nothing jiggly or loose in the switch so I am surprised. Thanks for the help everyone, Mark's list was a good guide to find the problem.