my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Digital Cinema Forum   » NC-900 Vertical Lens Shift Failure

Author Topic: NC-900 Vertical Lens Shift Failure Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 07-10-2014 02:23 PM                     I've had two NC-900's lens shift mechanism's go all the way up or down and get stuck there. Warranty service fixed one I have to fix the other. Beware! There is a wire going to the vertical positioning motor on the lens mount from the driver PCB that is likely to be pinched, especially on projectors delivered before the service bulletin. I found my wire jammed in between the spongy grounding material and a metal shield. There is a fix for it and the factory has been clipping the wire in a new position to the metal shield so this can't happen. When it gets pinched it shorts out the driver IC on the lens control board and puts the driver amp way out of balance causing the lens to go all the way up or down depending on failure mode. Those with early NC-900's may want to have their tech get a copy of this bulletin from NEC and check your machine to be sure it is not going to happen. Removing the lens mount in this projector to repair the pinched wire is a bitch! And above all do not install a new lens driver board until you know absolutely the wire is not pinched. It will blow the new board instantly. If you're comfortable with SMT soldering the IC looks easy to replace and In the future I'm going to carry a half dozen of the $2.00 IC's (L2726) in my tool kit and fix the boards in the booth on location instead of waiting for a replacement board to arrive. Note that you can keep the projector on screen by raising either the back end or the front end of the projector with 2X4's to keep the unit on the screen. I found the black wire in this one pinched down by the motor. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-10-2014 06:52 PM                     Thanks for the heads up Mark! Thankfully, we don't have any early NC900s. Note, I looked for the bulletin regarding this and didn't see it. Is it posted?  |  IP: Logged Ian Freer Expert Film Handler Posts: 135 From: Wellington, New Zealand Registered: Oct 2003 posted 07-10-2014 08:51 PM                     On the topic of NC-900 lenses, has anyone experienced an NC-900 lens ZOOM function stick? I have two particular projectors where this has happened. When changing to Scope, the shift and focus functions work but the zoom does not, so Scope ends up as a small image within a larger screen after the masking has opened. The projector/DCC does not report any error. The simple fix I've found is to take the front cover off, then change between flat/scope while giving the zoom-ring a little jiggle for a second. This free's it up and it then operates perfectly for many months. (Note: for those that don't know, taking the front cover off will activate a physical tamper alarm that will need to be cleared by a tech). One site has had it happen just once, the other has had it occur about three times on the one projector. (Both PJ's have been installed for around 9-12 months). I cannot recall now if the Flat position is at one extreme end of the zoom range. If it is that might partially explain why it sticks, but I'll need to double check that next time I'm on site. Cheers, Ian  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 07-10-2014 10:06 PM                     I'll send the bulletin to you Steve... First you need to be sure the projector has "learned" the lens. Some tech's overlook this. I had the motors on one lens die but NEC replaced it pronto. You should have your technician look at yours...  |  IP: Logged Ian Freer Expert Film Handler Posts: 135 From: Wellington, New Zealand Registered: Oct 2003 posted 07-11-2014 01:14 AM                     Hi Mark The lens was definitely calibrated during installation. I don't think I've missed a lens calibration yet. (The Setup Date, now that's another story... I missed setting that a few times in the early installs...) Cheers, Ian  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.