Ink Detection Adjustment - Ricoh C231 Service Manual

6.9.5 INK DETECTION ADJUSTMENT

PURPOSE: To ensure that the CPU detects a no ink condition.
ADJUSTMENT STANDARD:
See the following illustration.
CH
(Standard
CH
(Detection
CAUTION: This adjustment is required every time the MPU has been replaced.
1. Wipe off the ink around the ink roller beforehand (remove the ink cartridge ,use
SP 140, enter 0, and feed paper until the ink supply ends).
2. Turn off the main switch and disconnect the power plug.
3. Open the scanner.
4. Remove the MPU cover (2 screws).
5. Connect the CH1 probe of an oscilloscope to TP106, the CH2 probe to TP105,
and the grounding leads of both probes to TP110 (-12 volts). Select the 5-
microsecond range on the oscilloscope.
6. Connect the power plug and turn on the main switch.
7. Make sure that the waveform is as shown in the illustration while the ink end
indicator is lit.
8. If it is not correct, adjust the ON timing of the detection signal by turning VR101
beside the test pins.
NOTE: If the standard signal is delayed with respect to the detection signal, the
machine cannot detect the no ink condition. In such a case, LED101 on
the MPU will light to warn of this condition.
NOTE: If the ink detection off mode has been selected with SP 140, do not forget
to return it to the default (detection on).
SM
DRUM AND DRIVE SECTION
4 0. s
4+0.5/-0 s
0
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C231R571.WMF
C231/C237/C238