Gestetner B070 Service Manual page 1026

Tech Service Bulletin No. B070/B071 – 011
Step Item Purpose
LD power To determine the
4
adjustment LD light intensity
that will be used
for halftone areas
during
copying/printing.
5 ID pattern To update Vref
creation, for accurate toner
detection density control.
NOTE ON VD CORRECTION:
As the development sleeve accumulates toner over time, the gap between VD and VB decreases, which makes it easier for dirty background to occur. To
compensate for this, the machine increases the target VD value to -850±20V when the number of copies exceeds the value set with SP3903-1: VD Correction
Counter, (default: 200K). As a result, VD increases and the VD-VB gap is maintained. This value is cleared when the developer is replaced and initialized.
CONFIRMING THE SUCCESS OR FAILURE OF PROCESS CONTROL
Use SP3902-1 (Process Control Data Display – Auto Process Control) to
determine whether automatic process control has succeeded or failed:
• If this SP returns a "0" (OFF), auto process control has failed.
• If this SP returns a "1" (ON), auto process control has succeeded.
VALUES THAT DIFFER AMONG MODELS
Please note the following differences in the target values for process control parameters:
SP Mode
SP2001-7: VD
SP2201-1: VB
SP2201-3: Development bias for OHP
transparencies
SP2201-4: VBp (development bias used
when creating the ID sensor pattern)
Target VH
CÓPIA NÃO CONTROLADA
What Happens
Adjusts the LD light intensity until VH
falls within 260±20V.
An ID sensor pattern is created on the
drum surface (exposed and developed).
The ID sensor then checks the image
density of the developed areas
(output=Vsp) and bare drum
(output=Vsg), and the TD sensor
checks the toner concentration in the
developer (output=Vt). Vref is then
recalculated based on these values.
A294/A295
-970
-530
-530
-280
-290±20
CÓPIA NÃO CONTROLADA
SC Issued Related Display
If Fails SP
SC314, 316 SP3902-3: VH
SP3902-5: LD
Power (Correction)
SC350, SP3902-6: V ID
351, 352,
SP3103-1: Vsg
340
SP3103-3: Vsp
SP2223: Vt Display
A294ll/A295ll
-850
-650
-650
-280
-290±20
Reference
Comments
Manual Page
P6-68
P6-69
B070/B071
-800
-550
-400
-240
-260±20
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