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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » 701 readers

Author Topic: 701 readers Steve Anderson Expert Film Handler Posts: 168 From: Nashville, TN Registered: Feb 2000 posted 08-11-2000 09:33 AM                        I have quite a few 701 readers I am going to look at tonight.Nearly all are reading 8 or flat line. I checked the optical focus with the scope and it seemed within specs but when I went to adjust the voltage of the led and it was maxed out. Any tips?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-11-2000 09:35 AM                     What was the amplitued of the video you may be overdriving it Also check for jitter on the damper  |  IP: Logged Rory Burke Expert Film Handler Posts: 181 From: Burbank, CA, USA Registered: Jun 2000 posted 08-11-2000 11:33 AM                     Check LED voltage readings and if I recall properly unlike the CAT 700, the Cat 701 has the led piece glued on to the reader itself. In many cases just with moving the Led bracket slightly it corrects itself. about 50% of the time i find problems with these readers that it ends up being that Glued on piece. YUK! RORY  |  IP: Logged John T. Mellor Film Handler Posts: 52 From: Htafield, Pennsylvania, USA Registered: May 2000 posted 08-12-2000 11:57 AM                     If the 701 isnot reading and the voltage is maxed out , sorry but you need to replace the led . When you install the new one set the voltage to 4 volts realign and refocus the LED and lens . make sure you use a good test film when you set the 701 , if not your results will not be as good as you would like . I've replaced about 30 of them and they will degrade in 1 to 2 years  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-12-2000 01:51 PM                     Most of the cases where the LED has been blamed have really been bad alignment Often the Led creates an uneven top to the video amplitude. It takes patience to get a flat top line of the open perf vompared to peak performance. Practice makes perfect. A led that was new will get by missaligned better than when it gets older and marginal  |  IP: Logged Steve Anderson Expert Film Handler Posts: 168 From: Nashville, TN Registered: Feb 2000 posted 08-12-2000 04:52 PM                        I worked on 8 readers last night. I found that most of them were runing around 2.5 to 3V. I also noticed the jagged top line that Gordon pointed out. After bringing up the voltage and setting the focus I had 5 readers hitting about 4 on the readout. Gordon it sure is difficult to get that top line flat. Any suggestions on slowly moving the led head for adjustment? I also found that the LED voltage cable in the unit was not secure and rubbing against the flywheel! Another one had the tension spring on the damper unhooked. Is there another manual that has a break down of these parts? I have only the instllation manual which tells me nothing. Thanks for everyones help!  |  IP: Logged timothy johnson Film Handler Posts: 50 From: minneapolis, mN 55419 Registered: Jul 99 posted 08-13-2000 11:44 AM                     I have a question, I have a CAT 701 in my home screening room, and I got it brand new, and since I use it only 4 hours a week, can I assume it will last me for a good five years without replacing the LED ?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-13-2000 02:08 PM                     should last longer than that  |  IP: Logged Ken Jacquart Film Handler Posts: 82 From: San Francisco, CA, USA Registered: Mar 2000 posted 08-13-2000 08:45 PM                        Steve, When you adjust the 701's led assembly (loosen the 2 screws on the head and it will pivot ever so slightly...)adjust the upper perf trace for minimum sawtooth pattern on the scope. You won't get it perfect because you are literally seeing the droop in video amplitude between each LED segment. The LED array inside the capsule is 12 x 2... that is 2 rows of 12 (one above the other). As Gordon indicated, with patience you can get it pretty smooth. By the way, if you need a new LED assembly for the 701 reader, the Dolby part number is 83308. Also, we finally have a mechanical drawing which includes many part numbers for the 701 reader! I'll try to get a .pdf of it and get it to Brad to post in the manuals section. ken  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-15-2000 09:35 PM                     One thing I'm wondering about is how many of you are switching the LED on and off in between shows, or are you leaving it on all the time??? Had an interesting phone conversation tonight woth another Film-Tech techie about the red led's. We're wondering if frosting the face of the led slightly and difusing the light output would make it a bit easier to set up??? This might make it more like the Cat 700 light source which was a whole lot more forgiving to set up and was very easy to get looking reel good by a slight coaxing of the light pipe. Mark  |  IP: Logged Bill Purdy Expert Film Handler Posts: 139 From: Seattle, WA Registered: Oct 1999 posted 08-16-2000 10:12 AM                        NO! Don't try to frost the LED. It will cost you a whole lot of light and you may not be able to drive them hard enough and you sure will greatly limit their life because of the additional current. Remember that the performance of the LEDs is highly dependent upon their inner temperature. The lower the current the cooler and therefore the longer their life, so don't do anything to cause them to be operated at a higher current. ------------------ Bill Purdy Component Engineering  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 08-16-2000 10:18 AM                        I agree with Bill that "frosting" the lenslet surface of the LED will significantly reduce light output, and raising current to compensate will greatly reduce life expectancy. "Frosting" will also diffuse the light, and probably reduce the ability to sharply focus on the CCD. ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Eastman Kodak Company Research Labs, Building 69, Room 7419 Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com  |  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.