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Rank front end issues



                      Subject:                              Time:  10:36 AM
  OFFICE MEMO         Rank front end issues                 Date:  8/3/95
Rob and all...

    I've been monitoring with interest the recent dialog concerning PEC's,
tubes, etc. I have a few questions and, perhaps some useful information to
contribute.
    It's time to change PEC's again, and this time I'm considering using the
R3256-02's in all channels. The cost of these from Hamamatsu is $988.20 in
quantities up to 4. In quantities up to ten, the price drops to $768. The downside
is Hamamatsu is quoting a 5 - 6 week lead time. Rank has the 3256's in stock for
$875 each. 
    Our Mk III's use the Festival preamps. In changing from the 2154 to the 3256
in th Blue channel, I plan to change the gain resistor on the Blue preamp so that
it is identical to the R/G preamps. Anyone see anything unsound in this?
    At ITS a couple years ago I asked the telecine user's group whether it would
be feasible and beneficial to fit a Mk III with an Ursa HiLite (sp?) Kit.
Several people said it would never work without providing compelling evidence to
convince me it would be impossible. Larry at Rank - Chicago said it might be
possible. Does anyone out there have an informed opinion or experience with this
retrofit?
    Awhile ago I asked Steve Talley (now with Videotek) to make an R,G,B bowtie
signal to add to the Rank test signal library for the Magni 2021 signal generator.
It works and is helpful in setting interchannel timing. If anyone is interested,
I believe you can contact Steve at (503) 284-3293 or(503) 614-1939 (Videotek.) I
think he won't mind the plug. This test signal helped me to find and correct
timing errors in our da Vinci Analog Renaissance - running Prescan with a MkIII
C. Three years ago da Vinci had found and developed a moification to correct
timing errors on the Matrix board. However, they didn't automatically install
this modification in subsequent production units. You have to ask for it. The
modification in question is ECO # 0583. There are two other ECO's: #0445 and
#0661 which correct other problems on the Matrix board.
    Also while looking into channel timing errors, I found that OCCASIONALLY our
8:8:8 would exhibit a rather GROSS Y/C timing error. I didn't measure it, but it
appeared to be greater than 100 nSec. I was/am able to correct it only by taking
the system all the way down to Probug and then manually rebooting the system. I
suppose turning the system off and back on will work just as well. I reported
this to da Vinci, and they saw this problem in the factory. They reported that
it occurred in about one in ten logins. We have been running 4.1dKV software.
    Thanks to Dave Corbitt for the masking document on the Home Page. Dave, I'd
enjoy reading more about afterglow time constants and your experiences with
afterglow correction of the burn signal if you ever have the time and /or
inclination.

Tim