Film-Tech Forum ARCHIVE: Matrix/Azimuth problems with Ultra Stereo

This is topic Matrix/Azimuth problems with Ultra Stereo in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=003768

Posted by Michael Rourke (Member # 1142) on 07-25-2002, 12:14 PM:

Hi, I've searched for a similar problem to what I'm experiencing, which is crosstalk, and I have swapped out the Matrix card with one known to be working and there is no change, all the LED's are on with no fluctuation at all.

What do I need to check the azimuth? A RTA and/or a scope?

Does the Ultra Stereo have the Surround delay default switch, like the Dolby? I hope it does and that is the problem, because I had a tech here last night until four in the morning but we didn't get around to this problem before we all decided to pack it in.

Posted by Steve Kraus (Member # 476) on 07-25-2002, 01:05 PM:

To check azimuth you need an oscilloscope set to X/Y mode and pink noise test film. To adjust it you'll need those plus the RTA since in most cases you will be unclamping and moving the slit lens tube (conventional pickup) or lens tube (reverse scan) which will also affect focus. Many adjustments interact so it would not be a bad idea to have Buzz Track, X/Y, and, of course, Tone test films handy as well.

Posted by Joe Beres (Member # 678) on 07-25-2002, 01:41 PM:

Are you sure it's a problem with the processor? It could certainly be an issue with the solar cell or the focus of the exciter/led. Which Ultra Stereo processor do you have?

Posted by Darryl Spicer (Member # 711) on 07-25-2002, 02:09 PM:

Do a complete A-chain. but first run the dolby tone test film to make sure that the dolby tone is set correctly on the noise reduction card. When you do this make sure that the led on the matrix card is as low as possable. Clean the optics before you do this. If this does not help do a complete A-chain. Also when checking this make sure that all the lights around the projector head are turned off. Stray light can cause these problems.

On the older format cards you could turn the surround on or off on the newer ones you can't.

Posted by Randy Stankey (Member # 64) on 07-25-2002, 04:06 PM:

I've gotta' jump on the bandwagon on this one, too. You're going to have to A-Chain this puppy.

Another thing?
What kind of sound head is it? Reverse scan or exciter/solar cell?
When you use a solar cell instead of a reverse scan with electronic reader, you will almost always have a small amount of crosstalk in your system. That's just the way solar cells are. Properly adjusted, you can get the crosstalk down to a very small amount, indeed, but you can virtually never get rid of all of it.

If you are looking at the Matrix card of you USL sound processor and all the lights come on this MAY be a normal occurrence. During a movie they WILL come on. That's what they are there for... to tell you that the thing is working correctly. If they come on constantly or if they go out all together you know you have a problem.

First thing to do is get a piece of buzz track test film and a piece of Dolby Tone test film. Use the buzz track to make sure the film is running OK. Then use the Dolby film to make sure your Dolby Tone levels are at the proper settings. (Yellow Lights on the preamp card both JUST flicker.) Once you have that then adjust the "null meter" on the matrix card until you get the LOWEST reading. With a reverse scan sound head you should be able to get it down to just one light. With a forward scan (exciter/solar cell) you will be able to get it down as far as two if you try.

If this doesn't work, there's nothing you can do without an o-scope and an RTA and some more test film.

Just call your tech. He should know how to do this job in about 10 minutes flat.

PS: I forgot to mention... Clean your optics before you do anything. You would be surprised how the smallest amount of dirt or oil on your sound lenses can make BIG problems! I've had people call me up, crying crocodile tears, because their sound system wouldn't work. I would walk in, clean the optics with a Q-Tip and everything would be perfect! (On one occasion I was in the building for, litterally, one minute... Walk in... Clean lens... Walk out!)