I've discovered that in the Dolby Digital reader that I have on my Cinemeccanica projector there are two jumpers that, if in one particular position, can double the ccd sensitivity. Is it true? What are their purposes? isn't it better to have them always on the maximum gain?

The only thing to watch out for is that you don't start to introduce noise into the system.

I've re-set mine and the led current setting is now at its minimum, with error rates running in high 1's and 2's.

I'll do the others as time allows. I have all the equipment I need to realign fully but it does take time to get it at its best.

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what are these jumpers? can i found a datasheet on the internet?

A question: I've read that with a new LED you should stay between 2,5 and 4V. What is a "real" value? I mean, is it normal to reach 4V with a new led without overvolting the LED?

And what is the starting, or normal, voltage for a new led?

Bye!

The actual current the led's are running at is not the same as the signal voltage. One is the result of the other and depends on acurate alignment of the whole assembly.

Its really a job for someone that...
1/ has the correct equipment, without it DON'T GO THERE!
2/ has the time to 'play' and try different alignments.
3/ Who can really be bothered!

If you can find such a person.... do everything you can to hold onto them (him)!!

It's an unfortunate fact that many engineers will walk away saying 'that'll do'! It's your theatre and you should insist on the best..... that's the ideal. Getting it is a very different problem!

Thanks for your reply.

I wonder that because our tech stayed half a day to calibrate our new led and was unable to go further than 3V (but led current was not at maximum and withh 2X gain on the CCD). I believe that with a new LED you could reach the 4V easily...

Moreover, our Cinemeccanica led's brackets are not very good, it is almost impossible to setup an iron arm that is hold by just ONE screw at one side.

In the other screen I can't get 4v at 2X gain with an older led. I will change it when the error rates climb and I have no head room to play with.

Looking at some of the postings on Test films and alignment issues, how are you ment to set up SRD perfectly anyway. Azimuth varies from reel to reel in most prints, focus seems to drift and nothing is consistent between prints. I have a new print of the SRD jiffy test film. I tried using that to align a system. It looked fine on the computer but when running 'real' film the error rates were very high. So it was back to using new release prints.

Bottom line is how the system operates generally.

In the real world 'ideal' may not be atainable so don't lose any sleep over it. Provided the optical side is aligned correctly, you get consistant low error rates and very few reversions don't waste too much time.

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Our tech used both oscilloscope and DRAS. On the oscilloscope, however, he was not able to set the led to have, without print, 4V of peak voltage. Maximum was 3V with 2X gain and 500mV (mV?) on power supply.
I thought that with a brand new led you should be able to have 4V easily...