Minolta Di251, Service Manual

Page: 44 / 362

FrameMaker Ver5.5E(PC)Di251/Di351 MECHANICAL/ELECTRICAL
05.03.01
M-24
13-3. ATDC Sensor
• The ATDC Sensor detects the toner-to-carrier ratio (T/C) of the developer in the Devel-
oper Mixing Chamber.
1. An LED emits infrared rays to toner.
2. There is a phototransistor that converts the intensity of the light reflected off the toner to
a corresponding voltage value and outputs it.
3. T/C is determined based on the output voltage value.
(1) ATDC Sensor Automatic Adjustment
• The reference value for the ATDC Sensor is automatically adjusted as detailed below
using the ATDC Sensor Automatic Adjustment mode.
(2) Toner Replenishing Control
• While the I/C Motor is turning, the ATDC Sensor samples T/C and, according to the read-
ings, the copier provides the following controls.
✽
Toner replenishment represents the operation of the Sub Hopper Toner Replenishing
Motor.
T/C (%) Sampling Data (V) Control Details
More than 19 Less than 1.41 Defective ATDC Sensor
14 to 19 2.32 to 1.41 Toner replenished for 0 ms.
13 to 14 2.50 to 2.32
Toner replenished for 54 ms at intervals
of approx. 1 s.
12 to 13 2.68 to 2.50
Toner replenished for 150 ms at intervals
of approx. 1 s.
10 to 12 3.10 to 2.68
Toner replenished for 378 ms at intervals
of approx. 500 ms.
7 to 10 3.92 to 3.10 Passed onto the T/C recovery mode.
Less than 7 More than 3.92 Defective ATDC Sensor
The voltage input to the ATDC Sensor
from the Master Board is varied.
2.55 V or more: Decrease the voltage.
2.45 V or less: Increase the voltage.
Install a new I/C. This sets the copier into the ATDC Sensor Automatic Adjustment mode.
The developer is mixed.
The ATDC Sensor converts the reference T/C (14 %) to a corresponding voltage value
and outputs it.
Does the output voltage fall within the range from 2.46 to 2.54 V?
YES NO
The voltage input to the ATDC Sensor from
the Master Board at this time is fixed as the
reference voltage.