Performance Verification: AnalogS ection
WFM90D and WFM91D ServiceManual 4-11
VectorPhase Stability
This procedureverifies the following requirement:
Phase Shift with Subcarrier FrequencyChange from FSC to FSC 50 Hz
(FSC 10 Hz PAL):2°. P haseS hift with Burst Amplitude Change from
Nominal to 6dB:2°. Phase Shift with VariableGain Control Variedfrom
+3 dB to --6dB: 1°.
1. Connect a 75% color bar signal to the VIDEO IN connector.Set the input
switch to the 75 Ωposition.
2. Select VECTOR display mode on the WFM90D or WFM91D monitor.
3. Use the Phase controls to position the burst vector on the 180°graticuleline.
4. Check that when thetelevision generator subcarrier frequency is changed
50 Hz (10 Hz PAL)from nominal, that the display locks, and that the
burst phase has changed2°or less.
5. Return the subcarrierfrequency to nominal on the television signal generator.
6. Replace the colorbar signal on the VIDEO IN connector with a black burst
signal.
7. Check that the vector phasechanges less than 2°while varying the burst
amplitude fromnominal to 6 dB (1/2 to 2X amplitude), using the
television signal generatorburst amplitude control.
8. Return the burst amplitudeto nominal on the television signal generator.
9. Select VARGAIN ON from the Configuration menu.
10. Check that the vector phasechanges less than 1°while varying the vector
burst amplitude from1/2 to 1.5 times nominal amplitude using the variable
gain control.
11. Select VAR GAIN OFF fromthe Configuration menu.
12. Remove the signal input fromthe VIDEO IN connector.