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Re: Sparkles----------------



 Reply to:     RE>Sparkles---------------------
Some interesting clues, but are you sure there's a correlation
to all the various Rank modes?
 
Most of the random white flashes we get (aside from plain old 
memory/addressing fubars) is due to static discharge.  It is 
quite possible that you have air ionizers and/or ionized air 
knives on the Rank which are causing this.  This (or similar 
discharge) theory is supported by the fact that increasing the 
RH% seems to help.  Try turning off your ionized air just for grins. 
If that fixes it, try larger resistors in the Hipot feed, and 
check the outflow orifices where the ionization fingers are to 
make sure they are not crudded with stuff that may leak the charge.  
Also, it's a good idea to keep the humidity up anyway, so keep 
doing that. It's winter, so this problem will be at its worst, 
especially in winter climates, like north of the Mason-Dixon 
line.  Here in NYC, we see this type of thing come and go with 
the seasons. 

Another track to investigate is some discharge in your mains. 
perhaps a faulty wire or connector in your plant AC wiring is 
arcing over at sine wave peaks.  That might explain the banding 
and the correlation between 24 and 30 fps speeds.  Does not explain 
the other factors, like run-still difference.  This stuff can be 
tracked with "sniffers". You can try thos cable tracker devices 
like "Fox & Hound" and touch around the outlet plates in various 
locations.

Good luck. -bt


----------------------------
Date: 01-26-96  7:36
To: Topazio, Bill
From: JimErkson at aol.com

I've been having problems with "sparkles" on a Mk III, Digi IV Rank for some
time now.  Rather than go over the dozens of things that have been attempted
to relieve the problem, let me just say that the problem seems to be related
to static discharge; either of the film or something else, and that the only
thing that's been tried that has partially relieved the problem has been to
increase the humidity in the Rank area to around 55%.
The sparkles have the following characteristics:

1) They are one field in duration, followed by a clean field, followed by
another one field duration of the same sparkle in the same position.
2) They are colorless, white, and exceedingly small.
3) They all appear in the upper 1/3 of the picture area, within a horizontal
band approx 30 - 40 lines wide.
4) They are more numerous when running 30 fps versus 24 fps
5) They are far more numerous and elongated, horizontally, when running
backwards.
6) They never appear when the transport is still.