Installation manual

Dolby
®
Model CP650 Troubleshooting Chart Maintenance and Troubleshooting
9-10
Symptom Probable Cause Recommended Action
NO SOUND IN SOME FORMATS No analog film sound (Formats 01,04, or 05). Front-panel normal, Dolby Digital sound OK, and nonsync OK.
The analog LED or exciter lamp or power supply may have failed or the wrong projector may be selected. Solar cell connections may be loose or damaged. The remote solar cell preamp board used with LED analog readers may have failed.
If the signal-presence LEDs inside the access door are not flashing, verify exciter operation and solar cell connections as described above. Substitute known working Cat. No. 772 board.
No Dolby Digital sound (Format 10). Front-panel normal, analog sound OK.
Digital reader LED not working, Dolby Digital decoder board Cat. No. 773 not installed or not working, non- Dolby Digital print being played, film not threaded correctly in reader, reader failure.
Verify that the LED (or exciter lamp) in the digital film reader is on. Verify that the print you are playing is correctly threaded through the digital reader and that it includes Dolby Digital information . If the CP650 accepts a Format 10 command, the digital sub-system is probably still working.
No sound on external six-track input (Format 11, 70 mm, external Dolby model DA20, or other multichannel sound sources), Front-panel normal.
Cat No. 772 board defective. Wrong format, external device not receiving good data. Six-channel input connector not fully plugged in.
Check external device for audio output. Re-seat the six- channel connector.
No sound in nonsync
Nonsync source not working, nonsync level set too far down, faulty Cat. No. 772 board. If nonsync is a user format, is the input from Nonsync 1 or Nonsync 2? Which channels are the signals being sent to? Are those power amplifiers working?
Verify output of nonsync source. Determine from front- panel display which channels the output is directed to and verify that power amplifiers and speakers for those channels are working. After checking the above, adjust nonsync level in setup, changing both left and right channels by equal amounts.
Power button illuminated. Front-panel dark. There is sound.
System is in bypass mode.
Turn on the CP650 with the front-panel power button. Call service engineer if the system is still not operating correctly.