"Meat Plow" wrote in message
news
On Sun, 07 Jan 2007 02:54:25 +0000, Alasdair Campbell Has Frothed:
As I'm very close to a perfect image I don't want to mess with things
_too
much_ though it seems like I should investigate the Cutoff & Gain
options
for the Blue emitter?

I've searched for help on what these actually mean but I'm still fairly
clueless.

Any suggestions?

Alasdair

Go here and read.

http://www.electronics-lab.com/articles/files/crt.pdf
--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

Thanks for that link, I've learned more about CRT in 6 pages than I have in
20 years!

I'm not sure that things are working right with the adjustments, when in
service mode the picture comes up first a lot darker than in normal mode,
when I switch to the page that adjusts gain and cutoff the image gets much
better, though slightly too bright with poor black levels. I set R Gain to
max, reduced G & B until a good balance of colour was acheived. I notice
that the cut off for R.,G & B are all set to max! - maybe thats what caused
the flickering, so I reduce each cut off value arbitrarily. Am I right in
thinkthing that as Cut off value affects the level at which black is
displayed a higher cut of value would make the overal picture darker - as
signal levels normally displayed are 'cut-off' ? This would make sense as
when viewing the TV the picture was darker than it should have been.

I go back to normal mode and now the image has a strong Blue cast, as if the
B gain is too high. The problem with making any judgements on this is that
while adjustings these values the image is pretty good, once I go back to
normal running the image is noticeably poorer in one way or the other.

Why would the service mode display the image differently to normal running?

This is from the service manual:
"2. Follow the procedure below to set the Cut Off.
2.1 Adjust G2.
2.2 Tune a white pattern.
2.3 Adjust colour to minimum.
2.4 Position colorimeter in the centre of screen.
2.5 Adjust brightness and contrast to obtain a luminance of ~20 NITS.
2.6 Operate in Service Mode and select location RED CUT OFF, GREEN CUT OFF
and BLUE CUT OFF, to
obtain colour coordinates:
X=0.290 ± 0.015 Y=0.300 ± 0.015
To increase press volume-up button and to decrease press volume down button.
RED CUT OFF alter X coordinate.
GREEN CUT OFF alter Y coordinate.
BLUE CUT OFF alter X and Y coordinate."

From this I see I have no colorimeter, and don't know how to adjust G2 - but
supposing it was never adjusted in the first place that is no problem.
In reference to colour coordinates when in service mode there are two sets
of hexadecimal figures, like so
06 51 45 4C
06 06 06 50
presumably X and Y respectively. Or am I suppsed to read the coordinates
from the colorimeter?

Sorry for the confused queries...

Alasdair