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Trouble with.......

RE:	Trouble with.......

>       The most common causes for color drift that I've seen on Ursas and
MkIIIs (haven't >worked on Golds) have been temperature and line voltage
variations. You might want to >consider borrowing a chart recorder to check
temp/humidity (usually a dual unit) and/or line >voltage. Alternatively, you
might have a drifty internal power supply.
>       BTW, have you been able to monitor the Gold to isolate what's drifting?
Does it show up >on test signal or just a film image? Does one color vary or
>                                       Rich Torpey
Okay, so here are my thoughts....  As the machine is in Mexico, the following
applies....  We have to turn the machine off every night as we are subject to
power disruptions, we do have a UPS, but only good for a few minutes, do I trust
security to turn things of in the right order?

Anyway, is the Gold any different from the MK3 or URSA at the head end? Not to
my knowledge, so I suppose it could be a faulty PEC, therefore I would probably
get a drift just on one colour.  THis I have not assertained yet.  Temperature
and Humidity are fairly constant.  From what I can glean re the other drifting
Gold, is is something to do with a couple of Diodes placed in the head end so
that the A-D's do not overload.  As I understand things, as the diodes come on
line, by say varying temperature the signal changes and this also affects
shading as the bit mapping that takes place is mathematicaly interpelated for
the mid range that it measures to the high end correction.  Unfortunately, the
diodes change the linearity of the signal, thus the shading correction as well.

I have to do quite a few tests to assertain exactly what is happening, but
thanks everyone for your thoughts, I will look specifically for your suggestions
and report back. 

Ken Robinson
P.S. If anyone at Rank wants to jump in and comment, please do at any stage.