Film-Tech Forum ARCHIVE: U.S.L Dobly Digital reader problems

This is topic U.S.L Dobly Digital reader problems 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=008364

Posted by Jeff Else (Member # 4063) on 11-17-2006, 12:34 AM:

I have a U.S.L BACP DSTR 20 Dolby digital soundtrack reader hooked up to a dolby DA20, Ultra-stereo JS200 and component engineering TA-10 automation. The system is extremely sensitive to digital failure, and sometimes cannot play the digital soundtrack on certain brand new, carefully built movies, that will play fine on other identical setups. prehaps this issue is of fine alignment, etc.. and is above my head... but is there anything i might be able to do? also, all three U.S.L. readers have a "video status" light which goes between green and red. when i first started working at this theatre, 2 of the readers would normally be green, once threaded properly, and one of them always stayed red. Now they are all red. Is this telling me something?? the error rate on the DA20's are usually about 5-6 (I don't know if thats normal). Ideas??? I know this is alot in one post but those are all my U.S.L reader issues!

Posted by Darryl Spicer (Member # 711) on 11-17-2006, 03:58 AM:

Your l.e.d. voltage is too low. You are not getting a good video signal. If you remove the four screws holding the cover with the status light indicator. It is only a shield nothing is connected to it. Behind it you will find directly in the back a small hole with an adjustment pot behind it. Take a jeweler's screwdriver and adjust the pot clockwise till the status light turns green. This will increase the voltage. This should help the reader read the information properly. The l.e.d.'s may need to be replaced if you can't get the signal up to a green status or their is a problem with the video card.

Posted by Sam D. Chavez (Member # 1841) on 11-17-2006, 10:53 AM:

You are correct Daryl. The status light is an indicator of video level. Red is below 2 Volts, Green is 2 to 4 Volts, Yellow is above 4 Volts. Please note the status light yields valid information only when running film with an SR.D soundtrack.

The pot adjusts LED current which in turn raises or lowers the video level voltage.

When making this adjustment you should be running SR.D film.

Posted by Jesse Skeen (Member # 586) on 11-17-2006, 01:57 PM:

Does the volume go up to 11? [Wink]

Posted by Michael Schaffer (Member # 1204) on 11-17-2006, 09:55 PM:

quote: Sam D. Chavez
You are correct Daryl. The status light is an indicator of video level. Red is below 2 Volts, Green is 2 to 4 Volts, Yellow is above 4 Volts. Please note the status light yields valid information only when running film with an SR.D soundtrack.

Question, just out of curiosity: why? Isn't the video level the level of the flashes generated by the perfs?

Posted by Tristan Lane (Member # 1169) on 11-18-2006, 12:25 AM:

To my understanding, The video level is the amplitude of the signal generated by the CCD. Thus, if LED output intensity is increased, so is the video amplitude.

But, I remember hearing from several people @ Dolby that the only accurate way to measure video level is by using an O-scope. Is this still true? I'm guessing that the indicator on the BACP reader serves more as an idiot light for general troubleshooting.

Edit: But I do have the same question as Michael. I also wonder why the film movement is required in order to see a video signal.

Posted by Frank Dubrois (Member # 3042) on 11-18-2006, 01:17 AM:

If I remember correctly, our BACP reader lights turn green when film is threaded, it doesn't have to be moving. Maybe I'm remembering incorrectly, but I do remember checking all the video status lights and seeing them green while the projector is threaded but not yet started.

Posted by Sam D. Chavez (Member # 1841) on 11-18-2006, 11:13 AM:

Tristan,

We prefer the term "check engine Light". It is as you say just a general indicator of video level and can assist in adjusting LED current.

SR.D does not stop reading at 2 Volts, it's just a minimum voltage Dolby advise.

The state of the light gets iffy as to status unless film is running, particlarly if the light output is down to the 2 Volt level or up over 4 Volts.

Posted by Jeff Else (Member # 4063) on 11-18-2006, 01:25 PM:

Eureka! that did it... error levels are down.

thanks!