Ricoh FACSIMILE FAX77, Field Service Manual

Page: 124 / 197

Step Item
Procedure
7 Scan start 1. Access the SBU as explained in “Prepara-
position tion” above.
2. Set the oscilloscope scale to 0.2 V/unit
(vertical) and 0.5 ms/unit (horizontal).
3. Light the xenon lamp (see p. 2-24).
4. Place the scan line test chart [A] on the
exposure glass as shown.
5. Connect the oscilloscope to the test lead
as follows: Channel 1 to XVIDEO (pin 1 -
blue wire), channel 2 to VIDADJ (pin 2 -
red wire), and connect up the ground to
pin 4 (black wire).
6. Set the oscilloscope scales as follows:
Vertical - CH1 0.2 V/unit, CH2 2 V/unit;
Horizontal - 2 µs/unit.
7. Gently tap the SBU until the waveform is
as shown on the right.
The peak of XVIDEO must be within 4 bits
of the peak of VIDADJ.
8. Reset the oscilloscope to the Original set-
tings and repeat procedure 6 (scan line)
on the previous page. It may be neces-
sary to recheck procedures 6 and 7 until
the scan line is perfectly positioned.
9. Tighten the SBU securing screws.
3-19