Film-Tech Forum ARCHIVE: SDDS Drop-Outs

This is topic SDDS Drop-Outs in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Randy Stankey (Member # 64) on 06-21-2000, 07:27 AM:

Yeah, I know about many of the pitfalls of SDDS. I'm not trying to start another SDDS SUX thread, here...

It seems that our readers are dropping out again. The LED packs were replaced about 3 years ago. The voltage adj. pot. on 2 of them is all the way up and they are getting too dim to read reliably. It looks like they are going to need it again, soon. Actually, this part is all academic...

It seems that for some prints they run fine and for others they don't. It's usually only one reel that doesn't play well. In my experience it's usually R-2 or R-3. I can open up the player and look at the LEDs inside and see what track is (or isn't) reading. Usually it's the "P" track that blinks out.

From reading past threads, here on Film-Tech, I think I can put 2 and 2 together but I want to see what other people think before I put forth my theory.

Posted by Brad Miller (Member # 2) on 06-21-2000, 01:38 PM:

3 years is too long to expect to run SDDS without changing those leds. That's really the only option for you at this point. The reason some reels are playing is most probably due to the difference in a "lighter" printed track, allowing a little more light through.

Posted by Mark Gulbrandsen (Member # 72) on 06-21-2000, 04:13 PM:

I've seen the same thing happen with SRD on two occasions. One in a basement reader that had a bad segment in the led and the other in a penthouse reader although here the led looked fine. Some prints, and or reels would play and others will not. Changing LED's in both cases took care of it.
Brad is right about the density shift occuring between reels. This is a common thing in film.
Mark

Posted by Randy Stankey (Member # 64) on 06-22-2000, 07:16 AM:

We have 6 SDDS units.
Two of them are in houses that also have DTS. Those two players are just fine. The LEDS are almost perfect. Of course! We almost always play DTS in those houses so the SDDS hardly get used. Two houses get played almost constantly. Those players have the crummiest LEDS. They are the ones that have the adjustment pots all the way up and are just barely good enough. The last two get played about 60/40.

The pattern of failure is definately tied to frequency of use. Out solution is to bypass the reader if you're not going to play in SDDS. That saves on wear & tear, etc. (We teach a lot of newbies to always thread until they get good enough to handle the "if/then questions".)

Still, I can't help but wonder...
It always seems to be reel 2 that doesn't want to read right. It will momentarily jump out of SDDS every 4 seconds or so. It looks like it's the "P" track that's dropping out the most. I was just wondering if there was any connection to the edge marks that we discussed before. Traditionally those marks appear in R-2 most often but can be in any reel.
I ask because that is what the pattern of drop outs is, too... Mostly R-2 but sometimes other reels. Usually only one reel of a print does it.

Yes, I've seen SDDS tracks that are printed lighter or darker. I don't dispute the fact that that causes problems. Often you can spot those problems.

Posted by Scott Norwood (Member # 30) on 06-22-2000, 07:40 AM:

Randy--why not just swap out the SDDS readers in the DTS houses with the bad ones? That will (temporarily, at least) save you the cost of replacing the LEDs.

Posted by Randy Stankey (Member # 64) on 06-22-2000, 07:57 AM:

That's a possibility!

We were thinking about moving the DTS from one of the doubled-up houses to one of the ones that don't have digital. One of the two players always goes unused, so why not make use of it? We'll still keep one house "double digital", just in case.

Posted by John Pytlak (Member # 331) on 06-22-2000, 08:11 AM:

Kodak worked closely with Sony to optimize the exposure of our edgeprinted film identification to minimize interference with the SDDS soundtracks. The Kodak edgecode is printed in the magenta dye layer, whereas the SDDS data is carried by the cyan dye layer read with red light. The SDDS reader does not "see" the magenta-colored Kodak edgeprint, so it causes no interference.

AFAIK, the error correction capabilities of the digital sound systems are usually capable of coping with quite a few unreadable "bits". But in marginal situations (e.g., dim LEDs), other types of (non-magenta) edgeprint may cause enough interference to default.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

Posted by Randy Stankey (Member # 64) on 06-22-2000, 09:16 AM:

I wasn't refering to the Kodak edge marks. I was talking about the brownish yellow ones that are printed on by "computer". The ones that are on the non-soundtrack edge of the film.

You now, the ones that somebody else said might be part of the CAP code.

I was talking to another guy who seemed to be in the know about such things and he told me that they weren't supposed to be printing those edge numbers with the code anymore. I showed him a piece of leader with the numbers on it and all he said was, "Hmmm!" He didn't tell me whether or not he thought they would be interfering with the reader, though.

Posted by John Pytlak (Member # 331) on 06-22-2000, 09:46 AM:

The edge numbers are not necessary for CAP Code to work. They are just a "convenience" to verify the print number, and can be left off.

Posted by Randy Stankey (Member # 64) on 06-22-2000, 11:37 AM:

That's what I understand. I've seeen prints that don't have edge numbers that I know are coded.

It's just that I think that the ones that do have edge numbers are causing all the trouble.

The way it seems to be going is that a lot of prints run just fine on the SDDS, even if the LEDs are getting weak. At this point they are only "borderline". But when you combine a slightly out-of-spec. reader with a print that has edge numbers where there aren't supposed to be or if the SDDS track is slightly out of spec., then you get trouble.

I can take that print with the edge numbers and play it in another house and it'll be fine. Move it to one of the 'full-time' SDDS houses and it will play fine, except for reel #2 or #3. When you break that print down you'll see the edge marks.

Also, if you can open up your decoder while it's playing, you can read the reel number on the display. Also the LEDs on the PC board inside, (second and third ones from the left, if memory serves), tell you if a track is reading properly. It always seems to be the "P" track LED that blinks out right when the reader drops out. It happens at about 5 second intervals.

This is why I suspected the (vestigial) edge marks from the code.