I certainly hope that you have the complete service menu for this TV before
you change the service many parameters and forget what the original values
were, or maybe you have the fore sight to actually write down the parameter
locations and values before adjusting them.
Bias normally refers to the operating potential between the various
elements of the crt. Be it the differential measured from reference to the
cathode minus the value measured from the control grid; or it may be the
nominal potential measured at the respective cathodes with respect to
reference when producing a specified raster, be it flat white or totally
black.
The drives refer to the independent settings for each individual colour,
red, blue, & green. These are normally used to adjust for best over all
purity when doing the tracking from a dark raster to a bright raster.
Generally the bias is adjusted to produce a white raster without any
evidence of overdriving the crt. Adjusted to below the point where blooming
and retrace is being produced. Proper procedures will be laid out in the
service menu as per cutoff settings etc. The individual drive settings are
then set to minimize any shift in the colour of the raster when changing
from a dark, barely visable raster, to a bright, fully illuminated one.
Nomally called a tracking adjustment.
"ChrisCoaster" wrote in message
om...
I need information that is impossible to find on line and would help
me to deal with an issue on my TV. I'm serious - I've never seen it
spelled out black & white! If somebody could please fill me in on
the following:


Bias: What it means

What it does when it is adjusted


Drive: What it means

What it does when it is adjusted.


I recently just figured out how to access the Service menu on my new
Toshiba flat CRT, and I would like to correct a *slight* emphasis
toward red. Otherwise, picture is just great and I don't think I've
yet seen a TV picture so sharp and accurate out of box. So if just a
minor adjustment in either Bias or Drive could correct the red
emphasis beyond what the user "Tint"(R--|--G) could, please let me
know.

PS I take great notes - I've already written down the factory settings
for Bias, Drive, Color center point and Tint center in the SMs.

Thanks,

ChrisCoaster
"When you forget you are watching movies on a TV - THAT'S a damn good
TV! : )"

ChrisCoaster wrote:

Okay! Soooooh. Which one, drive or bias, am I safe to adjust to take
out some of the red??


I'm not familiar with your set exactly but before trying to do a
direct change make sure that this is not a "marketing" adjustment
that has it's own switch to be turned on or off.

For example, Sony has an intentional red boost in it's color
decoding. This makes the set's picture look really good in the
showroom but exact balance cannot be achieved (i.e., when setting
up the balance using color bars). In the service menu of some of
their sets, there is a switch where this option can be turned off.

- Jeff