Sharp SF-1014 Service Manual page 71

b. Void area adjustment
I. Summary
The copy image position on the copy paper is adjusted with
simulations 50-1, then the main corona grid ON timing for the
image lead edge on the photoconductor is changed with simula-
tions 45 to adjust the lead edge void area.
In concrete, in the case of the document table mode, the adjust-
ment is performed by changing the time interval from the scan-
ner motor ON to the main corona grid ON. In the case of the
SPF mode, the adjustment is performed by changing the time
interval from the SPF resist roller ON to the main corona grid
ON.
On the other hand, the rear edge void is adjusted by varying the
OFF timing of the main corona grid after the PPD detects the
rear edge of paper and turns off.
There are two kinds of the rear edge void adjustment. One is in
the tray paper feed mode, and the other is in the manual paper
feed mode.
Selection of the adjustment mode is made by the paper feed unit
select button and the display lamp.
Mode
Lead edge void amount adjustment mode
Read edge void amount adjustment mode
(Tray feed)
Read edge void amount adjustment mode
(Manual paper feed)
II. Purpose
The purpose of this adjustment is to improve separation in the
photoconductor section and in the fuser section and reduce dirt
on the fuser section pawl by obtaining the max. effective copy
area and the proper void area.
III. Note
If the proper void area is not obtained, the separation ability in
the photoconductor section may be degraded and dirt on the
fuser section pawl may be increased.
Before performing this adjustment, the following adjustment
must have been completed. If not, this adjustment cannot be
performed properly.
* Adjustment of paper pressure against the resist roller
(Sim 51-2 set value must be properly set.)
* Adjustment of copy image position (Sim 50-1, A, B)
IV. Cases when the adjustment is required
1) When the optical section is disassembled or its part is
replaced (including the scanner home position sensor).
2) When the main PWB is replaced.
3) When the RAM in the main PWB is replaced.
4) When "U2" trouble occurs.
5) When the resist roller unit is disassembled or replaced.
V. Necessary tools
* Screwdriver
* Scale
* Test chart
Scale
Manual
Paper
Paper feed
tray
unit lamp
Light —
Blink —
— Blink
7 – 21
VI. Adjustment procedure
(Lead edge void area adjustment)
1) Press the scale onto the document alignment plate and set
it horizontally as shown below:
2) Execute simulations 45-1. (C → 0 → 0 → C → 45 → CB →
1 → CB)
Simulations 45-1 is to adjust the size of the void area in the
lead edge of the copy paper.
The set adjustment value is displayed on the COPIES
SELECTED display.
Press the paper feed unit select button to light the tray
paper feed lamp and set the machine to the lead edge void
adjustment mode.
3) Set the adjustment value to "99."
Enter "99" with the numeric key, and press PRINT button.
4) With the document cover open, make several copies at
100%.
5) Measure the lead edge void area of each copy.
Void area
mm
1 0 20
1/2mm
Black background edge
Paper lead edge
6) Calculate the average void area.
7) Calculate the void area adjustment value from the formula
shown below.
Current set value (99) –
= Adjustment value (Decimal point rounded)
8) Set the adjustment value obtained in procedure 7).
(Decimal point rounded off)
9) With the document cover open, make several copies at
100%.
10) Measure the copy lead edge void area.
B4 or "14 x 8½" paper
Copy scale image
30
current void area (mm)
0.123