Film-Tech Forum ARCHIVE: Center channel failure on Ultra Stereo JS-200

This is topic Center channel failure on Ultra Stereo JS-200 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Tom Kroening (Member # 201) on 12-16-2002, 04:58 AM:

Hey guys, I'm having a very perplexing problem with an Ultra Stereo processor losing the center channel midway through a show. I have noticed a few key clues about this problem:

- It doesn't usually happen for the first show
- It usually only happens when playing in DTS vs analog
- After the problem occurs you can switch the center channel card with another card and then all channels will work just fine.

We had the same problem with the same processor a year ago and we swapped out everything including the processor unit except for the power supply. When I finally got a new power supply the problem went away until now. I have since then swapped power supplies with another processor and both had been running fine for two days. Now the problem is back.. an assistant of mine switch two cards around (yes i know this messes up the EQ but its not EQ'd to begin with) and the problem went away for the rest of the day.

The only thing I can think of is that somehow the power supply is getting damaged somehow... maybe some sort of power surge when the booth is shut down. Has anyone ever had a problem like this before? Anyone have some thoughts?

Posted by John Anastasio (Member # 607) on 12-16-2002, 06:41 AM:

I don't see how you can have a surge when you shut DOWN, since all you're doing is cutting the power at that point. It's a regulated power supply that's either working or totally dead in my experience. Power supply problems would also affect all the other cards as well. It sound suspiciously like crummy contacts that need cleaning. Swapping out the cards as you describe would clean them up enough to work for awhile, but then it will eventually happen again. I've had the same problem with video equipment. Pull the card, clean the contacts on the card, squirt a bit of contact cleaner on the card edge and then seat it and reseat it a few times and see if the problem goes away.

Posted by Jon Bartow (Member # 241) on 12-16-2002, 07:14 AM:

Hey Tom,
you say it usually happens in DTS not in analog. Check your cables and where they plug in very carefully. It sounds to me like there might be a loose connection there somewhere that when you are switching stuff around you are moving and reestablishing connection. Only later to have that fragile connection fail again.
If you have another house with the identical setup, try switching the audio cable from the DTS unit to the US processor. Also check the backplane on the US processor around the connector carefully to look for bad solder joints, etc.
But first, do as John suggested, get some contact cleaner and clean those card contacts.
jonathan

Posted by Mark Gulbrandsen (Member # 72) on 12-16-2002, 07:33 AM:

I would only use contact cleaner as a last resort in any case like this. If you do end up using the contact cleaner only apply it to the pcb's edge connector fingers sparingly using a Q-tip wetted in the cleaner. DO NOT SPRAY IT INTO THE MAINFRAME EDGE CONNECTORS!! If you use a really good grade of contact cleaner such as Caig De-Oxide( http://www.caig.com/ )it only takes a tiny bit to get rid of any oxidization. The stuff is expensive too!!
I once ridded 5 RCA TK-45 studio cameras of alot of intermittents with this stuff. The amphenol edge connectors they used were notorius for developing intermittents!

In your case FIRST start by checking backplane connections very carefully, then by swapping cards....probably the format card first in your case....since analog is ok. The format card takes the 6 track input from your DTS and routes it in place of the analog signal. These cards were very troublesome at one time anyway so thats a good place to start.
If its not the card it may be a bad DTS to Ultra cable, or the DTS itself may be bad. I've seen alot of different failures on the DTS processors since they appeared. They are extremely easy to repair in the booth!!
Mark @ CLACO

Posted by Gordon McLeod (Member # 33) on 12-16-2002, 11:35 AM:

A good place to look is the muting relay on each eq card
Since you say you move the EQ card and it goes away that is a possible and noted problem

Posted by Clint Koch (Member # 1179) on 12-16-2002, 12:21 PM:

Hello Tom,
All the suggestions so far are valid. I need to ask you a few questions abbout this unit. How old is the Unit? When you swap EQ modules and the problem goes away are you swapping them back to there original position at a later date? If not then the problem is not the relays like Gordon mentioned as the problem would follow the EQ module to the different channel. If you like you can call me at 805-549-0161 to get this resolved.
Clint

Posted by Tom Kroening (Member # 201) on 12-16-2002, 01:28 PM:

Wow, thanks for all the ideas. I'm sorry I never got around to documenting what we did last year (which i have since learned in my CIS networking classes is VERY important). The center channel just went out now and the problem did not follow the card. I pulled the center and dusted out the contacts. I did the same for the format card. I checked all of the connections in the back, everything is tight and in the correct spot. The monitor says its definately a processor problem, even though I reset the amp just to be sure. At this point I was willing to try anything. I pushed the bypass button in and then pushed it out... low and behold the center started to work again!

This has to be the strangest problem I have ever delt with. Its almost as if I'm somehow missing something here. The problem usually only happens in DTS but it persists even when you switch back into analog. I can't say for certain that the doesn't occur when playing in analog because the dialog bleeds to the left and right speakers so no one would notify us of a problem. I almost have a hard time believing that pushing the bypass in and out really fixes the problem... hmmm I guess I just wait and try again.

Posted by Gordon McLeod (Member # 33) on 12-16-2002, 02:58 PM:

It is possible that the problem is the bypass button on the older ones or the bypass relays since pushing it to bypass and back corrects the problem

Posted by Clint Koch (Member # 1179) on 12-16-2002, 03:11 PM:

Hello again,
Gordon is correct. It is most likely the bypass switch. If you remeber who you did the work through a year ago I can check our records to see if it may possibly be under warranty.
Clint

Posted by Karen Hultgren (Member # 395) on 12-16-2002, 03:19 PM:

If center channel drops out only when in DTS, send the DTS player in for repair. If the center channel disappears in analog too, then its either a CP or amp problem.

Karen at DTS
khultgren@dtsonline.com

Posted by Tom Kroening (Member # 201) on 12-18-2002, 05:33 AM:

Well its been a day and so far so good. After the show I pushed the bypass button in and out a few times and it has been working ever since. Unfortunately the card I swapped in there a year ago was not new, it was from one of our old theatres so its not going to be covered under warranty. I'll just keep an eye on this and see if I have to troubleshoot any further... Thanks for all the help!