8-1
SECTION 8
UNIT SERVICING / IN CASE OF DIFFICULTY
8.1
Troubleshooting During the Show
8.2
Problem Identification
8.3
Test Mode Operation
8.4
Starting and Program Loading
8.5
Failure in Digital Equipment
8.1
Troubleshooting During the Show
Your theater sound system consists of a number of critical audio components in addition
to the Dolby DA20 system. Thus, the first step when something goes wrong with the
sound is to find the source of the problem. The troubleshooting chart for your cinema
processor can often be helpful. If indications are that the fault lies in the DA20, the
procedures in the following paragraphs may be useful.
If you are unable to solve the problem using the information which follows, call your
service engineer. If he or she is unavailable, you may also call Dolby Laboratories’ 24
hour emergency number in San Francisco for expert advice: (415) 558-0200. You will be
asked to leave your name and number, and a Dolby Engineer will call you back promptly.
1.
If Digital Sound is Lost
• Switching to the analog track will occur if the Digital Soundhead is playing film
which is not in Dolby Digital format, or if the digital blocks have become unreadable
due to an obscured optical path or print damage. If frequent switching occurs, check
for print and optical path cleanliness.
• Check to make sure power is supplied to the DA20 processor chassis and the Digital
Soundhead exciter lamp.
• If power is present at the Digital Soundhead, but the exciter lamp is not lit, the lamp
needs to be replaced. Refer to page 2-1 for information on replacing the exciter lamp.
• If you are sure that power is applied to the DA20, but no LEDs on the front panel are
on, check the fuse in the power entry module on the rear of the DA20. If it appears
blown, replace with a spare fuse of the type and value specified on the rear panel of
the DA20.
• Check the video cable(s) from the Digital Soundhead(s) to the DA20 and make sure
both ends are properly attached.
• If the Auto Digital feature is enabled, disable it using the following method:
CP45 / CP55 / CP65—
Press and hold the Format 05 button on the Cinema
Processor for at least 4 seconds. The “Digital” LED on the DA20 will go off.
