Ricoh FACSIMILE FAX77 Field Service Manual page 121

Step Item
3 Check
4 Focusing
(MTF)
Procedure
If the waveform has irregular patches, the lens, mirror, exposure glass, white pres-
sure plate, or CCD may be dirty.
If the waveform level is lower at the ends than in the middle, the xenon lamp may
be wearing out.
If the waveform has sharp peaks or dropouts, the CCD may be defective.
1. Access the SBU as explained in "Preparation" above.
2. Set the oscilloscope scale to 0.2 V/unit (vertical) and 0.5 ms/unit (horizontal).
3. Connect the oscilloscope probe to XVIDEO (pin 1 - blue wire) and the ground
to GND (pin 4 - black wire) on the test lead.
4. Light the xenon lamp (see page 2-
24).
5. Place the 8 line/mm test pattern on
the exposure glass.
6. Loosen the lens securing screw [A]
(Allen screw).
7. Move the lens block back [B] and
forth until B is maximized (see the
diagram opposite).
8. Tighten the lens securing screw.
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