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Author Topic: Tracking down an intermittent sound problem. Brian D. Whitish Expert Film Handler Posts: 103 From: Seattle, WA, USA Registered: Apr 2001 posted 05-23-2011 10:35 AM                     I am going crazy trying to track down an intermittent sound problem. It is a high pitched whistling out the surround speakers. I can happen several times in a day or not at all for several days. When it happens I turn the amps off. Usually I can turn them back on for the next show and its fine again for the rest of the day. Equipment is Qsc 1500a amps, CP500, Surround EX unit, and component engineering monitor. Have replace one of the two surround amps in the last year and it still happens.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 05-23-2011 11:13 AM                        Do you have another CP-500 where you can swap ALL of the boards? Is the small jumper added to the chassis ground to the output low? (Only on later instruction manuals; first ones were wrong.) Louis  |  IP: Logged Andres Briano Expert Film Handler Posts: 162 From: Buenos Aires, Argentina Registered: Jan 2008 posted 05-23-2011 03:45 PM                        I´ve had this problem before. If you switch the SA10 (EX adapter) to Bypass, it´ll go away. That´ll solve your problems in the short term. I have not been able to fix it in the long term. Andrés  |  IP: Logged Christopher Schaffner Film Handler Posts: 33 From: Elizabethtown, KY, USA Registered: Feb 2011 posted 05-25-2011 09:39 PM                     I had the same problem before too. putting the SA10 in bypass also fixed it  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 05-25-2011 09:43 PM                     Sounds like one of the op-amp chips in the SA-10 is oscillating. Best advice is to get rid of the SA-10 altogether. I don't think Dolby even supports it anymore.  |  IP: Logged Chase Taylor Expert Film Handler Posts: 175 From: Troy, Alabama, USA Registered: Mar 2001 posted 05-26-2011 12:35 AM                        Same hear with the SA-10. Pulled it and the problem went away! Chase  |  IP: Logged Brian D. Whitish Expert Film Handler Posts: 103 From: Seattle, WA, USA Registered: Apr 2001 posted 05-26-2011 04:05 AM                     I tried putting mine in bypass, but it didnt work. I do think the sa10 is the problem. Im going to take it out and see what happens. Thanks for the ideas. I was sure not able to figure it out.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 05-26-2011 08:59 AM                     If you have to have EX I know where there is a stack of Panastereo EX units sitting that have also been pulled out.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 05-26-2011 12:51 PM                     Yeah, great idea Mark, let's remove something not supported by its' maker and replace it with something worse....  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-26-2011 02:25 PM                     What is wrong with the Panastereo equipment?  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 05-26-2011 04:56 PM                     Gordon/Mark, disregard previous post, had early morning brain fart and mixed my brands up...oops.  |  IP: Logged Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 05-30-2011 01:17 AM                     I have sent several Dolby EX units in for repair to curtail this problem. The annoying thing is that it pisses off all the customers because they are the ones who have to report it. Sometimes you can cure it yourself for a short period by pulling the EX motherboard from the backplane and reseating it. I have had one in bypass for over 6 months and I am planning on removing it from the audio system all together.  |  IP: Logged Ian Parfrey Phenomenal Film Handler Posts: 1049 From: Imbil Australia 26 deg 27' 42.66" S 152 deg 42' 23.40" E Registered: Feb 2009 posted 05-30-2011 04:15 AM                     Well, Smart DID buy Panastereo .. unfortunately.  |  IP: Logged

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