Video Amplifier Pcbs - Hughes JVC 100 Service Manual

Regulator PCB
/SWEEP_OK
/VIDEO_OK
2.8 Outputs
Video Processor
/ VAMP_OK
Video Amplifier
REG_G2
GND
G1
REG_VP

Video Amplifier PCBs

There are three separate Video Amplifier PCBs, one each for the Red, Green, and
Blue Channels. The Video Amplifier PCBs (VA PCBs) are located under the
necks of each of the three CRTs. The outputs from these video amplifiers connect
directly to the CRTs and provide all electrical connections to the CRTs except for
the anode voltages.
The following functions are provided by VA PCB:
Amplification of video signals and driving the cathode of all three CRTs
!
Sensing the cathode beam current for all three CRTs
!
G1 regulator for all three CRTs
!
Blanking drive section
!
DC restoration for the video signals
!
CRT interface for focus, heater voltage and ARC ground
!
The Video Amplifier Board I/O diagram (see Figure 2-19) and the list of Inputs
and Outputs (see Table 2-13) provide information for the technician to perform
module level troubleshooting.
2-46
Monitors sweep signals from the Video Amplifier PCB
Monitors Video Amplifier status.
Feedback signal to Video Processor.
+ 900V TO Video Amplifier PCBs
Ground
DC Bias + Blanking
Supply voltage to Video Amplifier PCB
Chapter 2---System Description
Model 100 Service Manual