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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Flickering Image On Screen Once Motor Is Turned On

Author Topic: Flickering Image On Screen Once Motor Is Turned On Aaron Mehocic Jedi Master Film Handler Posts: 804 From: New Castle, PA, USA Registered: Jun 99 posted 04-20-2004 07:11 PM                     This problem might be a simple overlook on my part but I need help in the diagnosis. I'm running a Kneisley Xenex II 3000 watt lamphouse with a Kni-Tron rectifier which by themselves are working normal. However, once the projector motor is turned on I've got a bad flicker in the image on the screen. Saturday night, the threephase breaker was tripped about four times, but has since settled down and cooperated. Since then the bulb is functioning on 85 amps instead of the rated 95. The rectifier was checked and compared with a perfectly functioning model of the same type and found to be just fine. The shutter was even checked for damage and realigned, though I did not think that would stop the flickering problem. Is it possible the motor to soundhead belt is worn out and needing replaced? (Simplex models) Any help would be appreciated thanks.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-20-2004 07:38 PM                     I have literally worked with hundreds of Kneisley rectifiers and lamphouses...actually even today at a Drive Inn in north central Wyoming which had a 4K conversion inside an old Strong Excellite 135! IN this case the threaded negative CXL adaptor had welded itself onto the bulb. I feel that you have a low phase in the rectifier so check CARFULLY the contactor and related AC wiring for burnt up stuff. This is fairly common in Kneisley stuff. If you find the rectifiers AC components o be ok then go back to the panel, or sub panel and carefully check there, but the best place to start in a Kneisley is at the contactor...measure the in and out sides to be sure the contacts inside have not burn't up. The low phase is causing some excess ripple on the DC which cannot be filtered out easily. The other possibility is that a diode has failed(open) and the ripple has gotten very high.... a good clue there is that your breaker now stays set. Disconnect all of the braided lead ends of the diodes and check them thet way. Mark  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 04-21-2004 03:07 AM                     Since you lost amperage and said the flicker is only present when the projector is running, my money goes on one open diode in the set.  |  IP: Logged Aaron Mehocic Jedi Master Film Handler Posts: 804 From: New Castle, PA, USA Registered: Jun 99 posted 04-24-2004 01:49 PM                     Thanks for your advice...it was a diode. The Kni-tron rectifier is, in my opinion, one of the better pieces of equipment out there and from what I've been told, diode problems are something that is more the exception than the rule. Once again you guys came through!  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-24-2004 02:54 PM                     The Kneisleys are ok rectifiers and provide VERY clean DC, especially the single phase units. There are downsides to them though.... because of the design of the transformer they draw huge amounts of current per phase compared to most other rectifiers, the fibre board that all the connections mount to can be a problem as the material used has a tendency to suffer from compression set causing connections to loosen up and then burn up. Transformer windings can also fail and catch fire... I've seen this happen. Mark  |  IP: Logged Aaron Sisemore Flaming Ribs beat Reeses Peanut Butter Cups any day! Posts: 3061 From: Rockwall TX USA Registered: Sep 1999 posted 04-25-2004 09:53 PM                     quote: Mark Gulbrandsen the fibre board that all the connections mount to can be a problem as the material used has a tendency to suffer from compression set causing connections to loosen up and then burn up. Transformer windings can also fail and catch fire... I've seen this happen. Odd, I have only seen those things happen to older Christie power supplies. -Aaron  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-26-2004 10:01 AM                     Yea, have seen that in Christies too. On normal scheduled service I always check this stuff but many theatres don't have norlmal scheduled service....... Mark  |  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.