Grass Valley 8901 - Manual (Page 11)

8901/8902/8906 Instruction Manual 11
Installation
DC Restore/AC or DC Coupling – J4
On all of these modules, set jumper J4 for the type of coupling desired:
• DC Restore (8902 and 8906) – set J4 to pins 1-2 for DC restoration. DC
restoration smoothly restores the blanking level DC components to
zero volts. This DC restoration circuit functions with or without syn-
chronization pulses and can therefore be used with GBR or YUV sig-
nals.
• DC Coupled – set J4 to pins 3-4 for DC Coupled mode. The DC Coupled
mode is recommended when distributing color difference signals (B-Y,
R-Y) or for simple non-reclocking fanout distribution of AES/EBU
1 V p-p coaxial digital audio signals.
• AC Coupled – set J4 to pins 5-6 for AC Coupled mode. Use the AC
Coupled mode when the incoming video signal has its blanking level
at anything other than zero volts.
Clamp – J5
The 8906 module has a clamp control that can be enabled or disabled and
the clamp speed set to fast or slow. When enabled, the clamping function
will override the coupling mode set with jumper J4.
On the 8906 module, set jumper J5 to enable and disable clamping and set
clamping speed as follows:
• Clamp Off – remove the shorting jacks on J5 on pins 1-2 and 3-4. You
may store the shorting jacks on pin 1 and pin 3. The clamp speed
shorting jack on pins 5-6 can be left in any position.
• Fast Clamp On – set the shorting jacks on J5 to pins 1-2, 3-4, and 5-6.
Also set jumper J4 for AC Coupled, pins 5-6. Use a fast clamp for appli-
cations where greater hum rejection is required.
• Slow Clamp On – set the shorting jacks on J5 to pins 1-2, and 3-4.
Remove the shorting jack from pins 5-6. Store the jack on pin 5. Also set
jumper J4 for AC Coupled, pins 5-6. Slow clamping is useful in applica-
tions where noise suppression is required.
White Clip – JP3
The 8906 module has a White Clip control that can be enabled to eliminate
positive-going pulses above a user-selected threshold set by the White Clip
Level potentiometer, R95.
On the 8906 module, set jumper JP3 to enable or disable the White Clip con-
trol:
• White Clip Off – set JP3 to pins 1-2.
• White Clip On – set JP3 to pins 2-3.