This is topic Ultra Stereo sound dropout in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Frank Dubrois (Member # 3042) on 07-20-2006, 07:45 PM:
Interesting problem here. Ultrastereo js-200 unit worked find until a few days ago, then the sound from the front became VERY low. The surrounds sound fine. The cards were removed and the contacts cleaned, cards replaced, worked fine again for about 20 mins, then back to very low sound levels up front. Coincidence? I have not had the opportunity to test anything yet, but I was wondering if anyone else had this problem before? Currently it will does not function as it should even when the card contacts were cleaned again. It is running in bypass.
[ 07-21-2006, 06:30 PM: Message edited by: Frank Dubrois ]
Posted by Mark Gulbrandsen (Member # 72) on 07-20-2006, 08:27 PM:
Over the years I've seen literally everything that can go wrong with these units... Most common problem is a failed format module, after that bad output relays... these can just be bypassed if your power amps have a delay on feature. Also, the power supply bypass button should be bypassed since every one of them fails eventually. Are both of the rail LED's lit on the power supply module when it fails or does one or both go out? If so just bypass the power supply button. Newer modules don't have the power backup button. Any of the other modules can also fail....swapping modules between units is the best wway to diagnose which module has failed. Be sure to keep track of which module camne from where and place it back there when you're done!
BTW: Gold plated card contacts shouldn't ever need cleaning.... gold does not oxidize and if you do clean it the coating is so thin (measured in microns) that improper cleaning will remove some of it and its plated quality. Use something like Caig Pro Gold or similar to clean gold contacts and above all don't clean them with a pencil eraser ![[Mad]](mad.gif)
. If fingers are bad then replace the card... if sockets(edge connectors) are bad then replace the backplane.
Mark
Posted by Frank Dubrois (Member # 3042) on 07-20-2006, 09:21 PM:
Unfortunatly we dont have another unit to swap cards with. I didnt spend a lot of time with it, and its all new stuff to me, so I didnt want to go poking around until I at least had a manual. The amp in the rack is a QSC 1400..and I didnt get a good look at it either. The surrounds in the auditorium sound fine, just the front speakers are very low. Unless your standing upfront, you cant hear anything. I'm hoping its something we can bypas or adjust, as of now, its playing in bypass mode.
Posted by James Westbrook (Member # 3690) on 07-20-2006, 10:15 PM:
Frank,
Is this auditorium running 2 channel stereo (center channel and surround) or 4 channel? If it's 4 channel, you could swap out a right eq card with the center and see if the volume in the front remains stable. (or the left eq card with the center).
Posted by Frank Dubrois (Member # 3042) on 07-20-2006, 10:29 PM:
I beleive its 2 channel. Since i'm completely unfamiliar with it, I remember it had the preamp card, NR card, two other cards, then the power supply. We have no spare cards to swap unfortunately. I notice there isnt a manual for this unit. Does anyone know if one of the manuals listed is pretty close? The JS-200 looks pretty similar. In reading the troubleshooting area, it says if the front speakers work in bypass, but not in normal play, theres a problem with the unit. The WHOLE unit? I would a think a card might be bad, but the whole unit?
Posted by Mark Gulbrandsen (Member # 72) on 07-20-2006, 11:28 PM:
Jumper the output relay in the center chan eq card... that may very well fix it, especially if its an old blue relay. I've had a number of failures of the later Aleph type relay too. A very common problem ![[thumbsup]](graemlins/thumbsup.gif)
.
Also, yank the format card out(with the power off) and look at the pins of the bypass switch... if they are gold the bypass switch is probably ok but if the pins are solver color then that switch also needs to be replaced.
If you have sound from the center in bypass mode then the power amp is not at fault.
Mark
Posted by Frank Dubrois (Member # 3042) on 07-20-2006, 11:37 PM:
Since I really didnt take a close look at it, and have never worked with this stuff before...what do you mean jumper the output relay?
Posted by Darryl Spicer (Member # 711) on 07-21-2006, 10:53 AM:
are you getting any sound from the front. Does it sound muffled. Turn off the surrounds and verify that the front has sound. There may be an issue with your center speaker's high frequency horn or crossover for that speaker. Note on your monitor if you have the ability to listen to each channel and in processor and amp mode on the monitor check the sound for clarity.
Posted by Frank Dubrois (Member # 3042) on 07-21-2006, 11:18 AM:
there is light sound from the front, but the surrounds drown it out almost completely unless your standing up front. In bypass, the front works.
Posted by Gordon McLeod (Member # 33) on 07-21-2006, 12:53 PM:
I would recdomend having a service engineer come in and deal with it
If you are not familiar with soldering technique I would not attempt it
I use a cleaning rubber from MG chemicals to remove build up on gold plated contacts as they may not oxidise but they do get enviromental dirt on them that can make them flaky
http://www.mgchemicals.com/products/802h.html
Posted by Clint Koch (Member # 1179) on 07-21-2006, 06:21 PM:
Hello all,
I spoke with Frank and had him try some things at the site today. What we came up with is the Standby switch on the power supply was causing the problem. When he pushed the switch on and off a bunch of time the center channel came back on. A servive repair power supply (without the Standby switch) is on it's way for Saturday delivery. Thank you all for your comments as they were all right on.
Clint
Posted by System Notices (Member # 2357) on 06-24-2011, 05:58 PM:
It has been 1798 days since the last post.
Posted by James Ness (Member # 4631) on 06-24-2011, 05:58 PM:
having this exact same problem right now
tried messing with the bypass button to no avail, tried taking the format card from another processor, no change.
hitting the bypass button works as normal, everything comes through the center and you can hear the dialogue clearly but as soon as you go back out of bypass it goes away again
all channels are fine except the center, its quiet and kinda muffled. was going to try the standby button but it appears as though mine don't have a standby button
any help would be appreciated, thanks
Posted by Mark Gulbrandsen (Member # 72) on 06-25-2011, 09:22 AM:
Power down the processor.... Pull the format card (the one with the fader control). Look at the contacts sticking up through the bypass switch. If they are not gold plated then the bypass switch is most likely bad. If you have gold plated contacts then you are probably ok and the problem lies some where else.
If you have another processor on another screen then substitute modules from it one at a time until you solve the problem. Be sure not to get the modules mixed up!
Mark