Ricoh VT3500, Service Manual

Page: 301 / 330

8.12 ADJUSTING INK DETECTION
Purpose: To ensure that the ink detection PCB detects a no ink condition
when the ink is running out.
Adjustment Standard: See the Above illustration.
1. Remove the rear cover of the machine.
2. Position SW901 [A] on the ink detection PCB to the oil type (upper)
position.
3. Connect the CH1 probe of an oscilloscope to TP1, the CH2 probe to TP2
and the GND lead to TP-12 V. Select the 5 microsecond range.
4. Turn on the main switch and install a drum with no ink. Or instead remove
the ink bottle and make prints until the Add Ink indicator lights.
5. Make sure that the waveform is as shown.
NOTE: 1. This adjustment should be made under normal conditions
(20°C/65 % RH).
2. The period of the waveform varies inversely with temperature.
(High temp.
→
reduced period, Low temp.
→
increased
period )
6. If it is not, adjust the ON timing of the detection signal using VR901 on
the ink detection PCB.
CH1
(Standard Signal)
CH2
(Detection Signal)
4
µ
sec
0
+
0.5
µ
sec
VR901
Oil-type
TP2
TP-12V
TP1
[A]
1 December 1993
5-67