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Author Topic: smart IIb processor hiss Charles Caron Expert Film Handler Posts: 188 From: Billings MT, USA Registered: Jul 2005 posted 03-14-2008 12:04 AM                     Greetings from the ubercrappy 7 ... mod 2c, center & surround channels only. BACP red reader. center channel has loud white noise type hiss,surround channel very light hiss, no hiss on nonsync. Red reader blocked/powered down, noise lessens slightly. Processor off, no noise. Second symptom/problem? touching red reader produces 60cy hum. Bad ground to sound head? ground loop? If I missed in my search, please point me to the proper thread, Thanks, Charles  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 03-14-2008 10:35 AM                     Check the BACP manual regarding a ground fix. If I remeber correctly you should link the (-) connection of the power supply input to the Ground of the Reader and then to your rack chassis ground. Do you have that hiss when you have the reader off? If you have a ground issue you should see the two green leds on the BACP reader slightly glowing when you have no film on the path and you have the reader ON. If you have the reader on and you don't see a slight glow on the Leds then most probably you are OK. Just a suggestion. Demetris  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-14-2008 12:21 PM                     On smarts website in the tech tips used to be a fix for reverse scan and Jaxlight hum issues Grouding sounds like an issue Pull the preamp card and see if the hiss goes away Also is the hiss there in mono as well as both stereo and sr if it in all film formats I would suspect the preamp otherwise the matrix card or the NR card  |  IP: Logged Charles Caron Expert Film Handler Posts: 188 From: Billings MT, USA Registered: Jul 2005 posted 03-14-2008 11:30 PM                     I swapped out all cards one at a time, swapped out power supply, no luck. Noise occurs in all except music. Something on the backplane maybe?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-15-2008 01:07 AM                     did it go away with the optical preamp removed ? it could be calibration issues as well and it is clear there is a grounding issue from the comment about touching the reader  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-15-2008 11:25 AM                     Charles, First check the Smart modification for reverse scam readers. If its been done then.... Since some buildings have very strange grounding systems try grounding the terminal on the BACP that says (gnd) to the frame of the sound reproducer/projector. Normally this terminal is not connected in a normal install but on a couple of occasions with Smart processors sometimes it does the trick. Inversely if its connected you may want to disconnect it and see if things improve. Also... like Gord says pull the solor cell preamp and then see if the sound goes away... likewise you can pull the module out of the BACP reader while the solor cell preamp is in place...  |  IP: Logged Charles Caron Expert Film Handler Posts: 188 From: Billings MT, USA Registered: Jul 2005 posted 03-16-2008 09:08 PM                     Mark: tried both of the above... still no joy  |  IP: Logged

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