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Chapter 2—Functional Description
Model 330, 340SC and 370SC Service Manual 2-51
Vertical Deflection Board
Inputs
Description
VPARAB
A periodic, positive-going, parabolic waveform with the
vertical scan frequency, used for dynamic focus.
HPARAB
A periodic, positive-going, waveform with the horizontal scan
frequency, used for dynamic focus.
/SWEEPOK
A TTL DC level signal indicating that, when low, indicates all
flybacks are occurring at or above a minimum frequency.
Video Amplifier Board
Inputs
Description
RBEAM
Voltage signal proportional to cathode current averaged over
several horizontal lines, in the red CRT. Voltage level is
+1mV/uA.
GBEAM
Similar to RBEAM.
BBEAM
Similar to RBEAM.
/RVIDOK
Open collector signal indicating the health of the red +100V
cathode supply.
/GVIDOK
Similar to /RVIDOK.
/BVIDOK
Similar to /RVIDOK.
Video Amplifier Board
Outputs
Description
BLANKING
Pulse signal output that is a buffered replica of the VIDBLANK input
from the SCB. Indicates the commanded blanking interval during
the scan.
/BENABLE
Logical connection of video amp, sweep, and power health
indications. TTL level output.
/RENABLE
Identical to /BENABLE.
/GENABLE
Identical to /BENABLE.
RVOUT
Red video output. 0V to 1V (TP1).
GVOUT
Green video output. 0V to 1V (TP2).
BVOUT
Blue video output. 0V to 1V (TP3).
CLAMP
Pulse signal output that is a buffered replica of the SCRSTR input
from the SCB. Indicates the commanded timing and duration of
the DC restore.
External Video
Inputs
Description
RVIDCH1
Red video input to channel 1.
RVIDCH2
Red video input to channel 2.
GVIDCH1
Green video with optional composite sync signal input to channel 1.
GVIDCH2
Green video with optional composite sync signal input to channel 2.