Grass Valley 8936 - Manual (Page 13)

8936 Instruction Manual 7
Module Alignment
Module Alignment
This section discusses Alignment Equipment and EQ Warning Adjustment.
Alignment Equipment
The 8936 module is fully aligned at the factory and normally requires no
adjustment in the field. If adjustments are necessary, they should be
attempted only by qualified technicians using, at a minimum, the fol-
lowing equipment (or equivalents):
■ 270 Mb/s serial digital video test signal source with pathological test
signal
■ Textronix WFM601 Waveform Monitor (or equivalent)
■ 300 meters Belden 8281 cable (or equivalent)
EQ Warning Adjustment
A variable resistor (R36) allows the user to adjust the corresponding cable
length at which the EQ warning LED illuminates.
When R36 is turned counterclockwise, the EQ warning LED will turn on at
shorter cable lengths. The EQ warning LED comes on at longer cable
lengths when R36 is turned clockwise.
Follow the steps listed to adjust the EQ warning:
1. Connect a length of cable, approximately 20 meters longer than the
desired length at which the EQ warning LED should turn on, to the
input. The factory default is set for 300 meters. Terminate the unused
input with a 75
Ω termination.
2. Turn R36 clockwise until it stops. Refer to Figure 6 for the location of
R36.
3. Connect a 270 Mb/s serial digital video signal to the selected cable.
Verify that a signal is present.
4. Turn R36 counterclockwise slowly until the EQ warning LED just turns
on. The module is now set.
Figure 6. R36 Location
8936
R36
8110-07