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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Analog sound problem...

Author Topic: Analog sound problem... Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 01-20-2007 12:09 PM                     Equipment: Dolby CP-50 w/Cat280T's, Smart amplifiers, Kelmar reverse scan LED reader Problem: Sound sometimes does not come on at the beginning of a show. Also, the sound will occasionally cut off for 10-20 seconds during a show. LED is visibly on, Amplifiers and Processor are on. Turing the LED off and then back on will sometimes solve the problem. I replaced the Cat108 preamp card in the processor but the problem continues. I also checked wiring to the processor and LED reader. Power rails on the backplane of the CP-50 were also checked and were at normal levels. I am confused as to what is causing the sound to cut off. Any help would be appreciated.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-20-2007 12:39 PM                       Not much to go on here. Does it happen often enough for anybody to sit there and wait and watch? he meters on the Cat. 109 would be a good place to watch or the signal presence lights on the Cat. 150 if it's new enough to have them. Either would at least tell you where and when the sound quits. Any CP50 with 280's puts a strain on the power supply and can cause sporadic operation. There are newer versions of the supply around but they are getting very rare and it's considered impractical to spend much money on a very old (sob) processor. You could try having the power supply rebuilt with new caps and diode bridges. Do you have a spare?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-20-2007 01:08 PM                        The key here is that recycling the led helps some. We have found some Kelmar power supplies (older ones with a board with pin connections) develop a loose connection on the wires that feed the preamp powser supply. Although it could require replacing the board, so far, I have resoldered the output pins and the resistors near them and had no problem. These boards are off-the-shelf and Kelmar is not at fault. Louis  |  IP: Logged Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 01-20-2007 03:19 PM                     When the sounds cuts off, there is no signal to the 150 card (green LED's are not lit). Also, I have several spare power supplies and I tried replacing the power supply with no positive results. I suspect something is wrong with the LED reader.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-20-2007 05:47 PM                     I have had two intermittent solor cells in Kelmars in the past few years... and these were in the early Kelmars not in any recent units. I now carry an extra one in the van!! Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-20-2007 06:01 PM                     I have had several cell failures recently  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-21-2007 07:34 AM                        These were early Kelmar units also. I would not think the cell would be stressed or repaired by application of power; that is why I did not suggest that. The loose power connections would be so affected. Louis  |  IP: Logged Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 01-21-2007 07:43 AM                     Just a thought. I've had a few problems in the past with CP50's that have the DTS breakout board on back. Since that cuts off the analog signal, that may be something to check.......if it's on there.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-21-2007 01:19 PM                       If the lights go out on the Cat. 150 when the audio is lost this means the problem is upstream of that. I assume the DTS board is downstream on the 150, no? The next thing to try perhaps is running the CP50 in bypass for a while. If you lose the sound again, it is almost certain a reader problem.  |  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.