User`s manual

Dolby
®
CP650 Digital Cinema Processor User’s Manual Operating Instructions
2-13
2.3 Bypass Operation
The CP650 has an independent power supply for emergency operation. If the main
power supply or processor circuitry fails, the unit automatically switches to bypass
operation, allowing the show to continue with limited sound processing functions.
The front-panel bypass power button glows red when the unit is operating in bypass.
In the case of other problems, such as distortion or the loss of a channel, Bypass mode
can be selected manually by pressing the bypass power button.
Other components in the theatre sound system could also fail. Refer to Chapter 4 any
time there is a problem.
When the CP650 is operating in Bypass mode:
• The bypass button glows red.
• Only the front-panel main fader operates; no other remote fader works.
• All other front-panel buttons do not work.
• The optical preamp circuit of the selected projector remains operational and is fed
to the CP650 Left, Center, and Right channel outputs.
• Even when a stereo print is playing, a mono signal is fed to all screen speakers.
Thus, you can switch to Bypass mode to keep the show going if one of the power
amplifiers fails.
• All Dolby processors, speaker equalizers, and subwoofer circuits are switched out
of the signal path.
Be sure to follow the troubleshooting procedures and, if necessary, call your service
engineer as soon as possible.
If the front-panel bypass power supply failure indicator (located directly above the
main fader knob) is on, the CP650 will not operate in Bypass mode.
Note: The CP650 will not operate, even in Bypass mode, if there is a fault in any of
the following areas:
• The AC mains power to the CP650
• The bypass power supply fuse or bypass power supply circuit
• The optical preamplifier circuitry or bypass circuitry on the Cat. No. 772B board
We strongly recommend that a spare Cat. No. 772B board be kept on hand for
substitution in emergencies.