Ricoh G148, Service Manual

Page: 461 / 537

If the ID sensor output cannot be adjusted to the standard, then after 20 seconds SC353 or SC354 is
issued. Toner supply during copying will then be controlled using the TD sensor only, until the machine is
repaired.
TD Sensor Calibration (Vref)
Next, Vref (TD sensor reference voltage) is updated using the latest calibration values from the ID sensor.
Vref is updated to stabilize the concentration of toner in the development unit. By shifting the value of Vref,
the density of the ID sensor pattern image is controlled. Toner supply control is covered in the Development
and Toner Supply section.
Vref is determined from a table in the machine software, using the following values:
• Vsp/Vsg
Vsp: ID sensor output when checking the ID sensor pattern.
Vsg: ID sensor output when checking the bare drum.
• Vref-Vt:
Vref is the TD sensor reference voltage
Vt is the current output voltage of the TD sensor.
If the ID sensor could not be calibrated during the latest process control (when measuring Vsg), then the
previous ID sensor value is used. If the ID sensor output is abnormal when measuring Vsp, SC350, 351,
or 352 is issued, and Vref is not updated (the machine uses the previous value).
6. Details
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