Sony HDW-730 Operation Manual page 140

If automatic black balance adjustment cannot be made
If the black balance adjustment cannot be completed normally, an error
message will appear for about 3 seconds on the viewfinder screen (in
display mode 2 or 3).
Possible messages are listed below.
Error message
BLACK : NG
4
IRIS NOT CLOSED
BLACK : NG
TIME LIMIT
BLACK : NG
R (or G or B) : OVERFLOW
If any of the above error messages is displayed, retry the black balance
adjustment. Keep pushing the AUTO W/B BAL switch to BLK until -
BLACK SET- appears after the -CHECK- appears. If the error message
occurs again, an internal check is necessary.
For information about this internal check, refer to "Maintenance Manual".
Note
If the lens cable is not firmly connected to the lens connector, it may not
be possible to adjust the lens iris. If this happens, the black balance will
be incorrect.
4-4
Chapter 4 Adjustments and Settings for Recording
Black balance adjustment error messages
Meaning
The lens iris did not close; adjustment was
impossible.
Adjustment could not be completed within
the standard number of attempts.
The difference between the reference
value and the current value is so great that
it exceeds the range. Adjustment was
impossible.