Gestetner G060 Service Manual page 967

Tech Service Bulletin No. G060/G570 – 027
Page 2 of 3
2. Difference between SP7-833 and SP7-908
Both calculate the pixel coverage ratios mentioned above for each toner color, however the calculation is
different for Bk pages printed in Color development mode (i.e. development with the transfer unit in contact
with all 4 PCUs). Please also see the example below.
SP7-833-5 to 8 (Coverage)
The total pixel area for Bk pages made in Color
development mode is added to the cumulative
count.
! SP7-833 (existing SP mode):
The idea of this mode is to show the pixel coverage ratio for each color for pages made when the
machine operates with the transfer unit in contact with all 4 PCUs. So even though no CMY toner is
actually being used for Bk pages in Color development mode, this SP mode includes the total pixel area
for these pages.
NOTE: This data is used for process control and toner refresh.
! SP7-908 (newly added):
The idea of this mode is to show the pixel coverage ratio for each color for pages made when CMY
toner is actually being used to develop the image.
As shown in the example below, for print data containing Bk pages, the ratio calculated by SP7-833 will
be lower.
Example:
When printing the following 3 pages, the average pixel coverage ratio will be lower with SP7-833 as shown in
the table below.
1st Page
Color
C: 7%
M: 8%
Y: 3%
K: 7%
Average pixel coverage ratio:
Bk
SP7-833 (7%+8%+6%)/3 = 7%
(7%+8%+6%)/3 = 7%
SP7-908
REMARKS:
! To enable SP7-908 in production units, the following have been modified-
$ Engine main and controller firmware (from March '02 production):
Engine: version B1.17C or later
Controller: version 2.13 or later
$ BCU NVRAM: 4 KB → 8 KB type for storage of paper size pixel area data. (P/N 14075751)
NOTE: The 8 KB type can be used on all machines. The machine automatically recognizes whether the
NVRAM is a 4 KB or 8 KB type.
This value is not added to the cumulative count.
2nd Page 3rd Page
B&W
K: 8%
Cyan
(7%+6%)/3 = 4.3%
(7%+6%)/2 = 6.5%
SP7-908-1 to 4 (New Coverage)
Color
C: 6%
M: 9%
Y: 4%
K: 6%
Magenta
(8%+9%)/3 = 5.7%
(8%+9%)/2 = 8.5%
Yellow
(3%+4%)/3 = 2.3%
(3%+4%)/2 = 3.5%
Continued...