Performance Verification: AnalogS ection
4-8 WFM90D and WFM91D Service Manual
2. Select VARGAIN ON from the Configuration menu.
3. Check by adjusting theVariable Gain controls that the signal amplitude can
be displayed lessthan 70 IRE (500 mV PAL).
4. Set the VACfor a 799.9 mV output.
5. Check by adjusting theVariable Gain controls that the signal amplitude can
be displayed greaterthan 140 IRE (1000 mV PAL).
6. Select X5 GAIN from the Operating menu.
7. Set the VACfor a 399.9 mV output.
8. Enter the Configurationmenu and select the VAR GAIN category.
9. Check by adjusting theVariable Gain controls that the signal amplitude can
be displayed lessthan 140 IRE (1000 mV PAL).
10. Set the VACfor a 159.9 mV output.
11. Check by adjusting the VariableGain controls that the signal amplitude can
be displayed greaterthan 140 IRE (1000 mV PAL).
12. Replace the VACsignal on the VIDEO IN connector with a pulse and bar
signal using a 75 Ωin-line termination.
13. Check by adjusting theVertical Position controls, that the white bar and
sync tip portions of the signal can be adjusted to the graticulebaseline.
14. Select VARGAIN OFF from the Configuration menu.
15. Select X1 GAIN from the Operating menu.
Overscan
This procedureverifies the following requirement:
≤2% variation in baselineof 100 IRE (700 mV PAL)12.5T (20T PAL)
modulated pulse as it is positioned over the middle 80% of the screen.
1. Check that the amplitude of the sine wave at the bottom of the mod pulse
varies less than 2% while using the VerticalPosition controls to position the
signal over the middle 80% of the graticule.
2. Remove the pulse and bar signal from theVIDE O IN connector.