Dolby Laboratories DA20, Руководство по установке

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3-1
SECTION 3
CAT. NO. 700 DIGITAL SOUNDHEAD ALIGNMENT
3.1 Cat. No.700 Digital Soundhead Alignment
3.2 Test Setup with Oscilloscope
3.3 Focus Adjustment
3.4 Exciter Lamp Level Confirmation and Adjustment
3.5 Film path Alignment
3.6 Optical Alignment
3.1 Cat. No. 700 Digital Soundhead Alignment
Mechanical alignment of the Cat. No.700 Digital Soundhead consists of making sure the
film path through the Digital Soundhead is aligned with the path through the rest of the
projector.
1. Thread a length of film from supply reel through the Digital Soundhead (refer to
the threading diagram located on the soundhead), and on through the projector as
you would any film.
2. Apply tension to the film and inspect for equal tension on both edges of the film.
3. Check for uneven forces on the rollers, or twisting of the film.
4. When the path is aligned, tighten the soundhead mounting bolts and reel arm.
3.2 Test Setup with Oscilloscope
The following test setup will enable adjustment of focus and confirmation and adjustment
of lamp level and optical alignment.
1. Make sure power to Cat. No.700 Digital Soundhead is provided. Power to the
DA20 should also be turned on.
2. Remove the DA20 front panel (see Section 8).
3. Connect a probe from Channel 1 of a 20MHz or greater bandwidth oscilloscope to
the VIDEO Test Point (TP1) on the Cat. No.670 Video Acquisition Card in slot 12
of the DA20(leftmost card), with the ground lead attached to VGND (TP2, just
below TP1).
4. Connect a second probe from the scope’s Channel 2 to the CLAMP signal test point
(TP3) to trigger the scope. Connect the second probe’s ground wire to DGND
(TP7).
5. Set the trigger source on the scope to Ch. 2.