Zeiss humphrey HFA II-i series Field Service Manual page 452

FA2i-026
3.0 'After Calibration' Verification Data (App H.2)
3.1 Total Working Wedge Attenuation
3.2 Your 'After' foveal threshold
3.3 White Projector Voltage Drop
3.4 dB Spread (White)
3.5 Reading in FT-L for 29db
3.6 Reading in FT-L for Bowl (White)
3.7 *Blue Projector Value
3.8 *dB Spread (Blue)
3.9 *Reading in FT -L for Bowl (Yellow)
* For instruments equipped with Blue/Yellow only
4.0 Worksheet (App I)
dB ratio = 10*Log(BKGDFtL / #37FtL)
Note: #37 is the same Ft-L value as the 29 dB data point on the White Light Verification Printout.
1. Using above formula & values from the BEFORE White Light Verification Data Printout,
find the OLD dB ratio:
2. Using above formula & values from the AFTER White Light Verification Data Printout,
find the NEW dB ratio:
3. Find the dB shift:
(OLD dB RATIO) – (NEW dB RATIO) = dB shift
Do you need to leave the calibration notice?
If dB shift is +/- 1dB, DO NOT leave the notice.
1.
2. DO NOT include (+) or (–) signs on the notice.
If dB shift is (+), select low on the notice.
3.
If dB shift is (–), select high on the notice.
4.
5. If ±1dB or greater shift, leave the cal notice.
6. If ±4dB or greater shift, call your regional manager.
Leave Notice?
dB
dB
dB
0 0
Yes No
___________________
___________________dB
___________________v
___________________dB
___________________FT-L
___________________FT-L
___________________v
___________________dB
___________________FT-L
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