Chapter 2—Functional Descriptions
high resulting in shutdown of grid bias at the Video Amplifier Boards. Also, the SWEEPOK status bit will be transmitted as a low to the SCB.
/GVIDOK
Similar to /RVIDOK.
/BVIDOK
Similar to /RVIDOK.
Output
/HVEN
When either /RVIDOK, /GVIDOK, or /BVIDOK from the Video Amplifier Boards is pulled high, or the +5V power on the Video Processor Board goes low, /HVEN is pulled high. This results in the HVPS being disabled, thus shutting down high voltage to the CRTs.
/RENABLE
High will cause grid voltages at the VAB to be pulled low shutting off the red CRT beam. High will result from high on /RVIDOK, /GVIDOK, or /BVIDOK from the VAB, +5V power going down on the VPB, or /SWEEPOK being pulled high from the VDB.
/GENABLE
Similar to /RENABLE.
/BENABLE
Similar to /RENABLE.
Internal
None
Video Amplifier Board P/N 103567 or 103774 (VAB)
The Video Amplifier Board (VAB) is mounted on and plugs into the back of the CRT. There are three (3)
The following functions are provided by the VPB:
Connection of all voltages to CRT.
Amplification of video signal.
Blanking.
DC restore.
Bias voltage control.
Model 330. 340SC, and 370SC Service Manual |
