JVC 250 service manual System Controller PCB - Operation

Chapter 5---Electronics

RGB_THRES - red, green, or blue Threshold correction information to the Video Processor PCB.

RGB_SENS - red, green, or blue Sensitivity correction information to the Video Processor PCB.

ISYNC - 5 MHz clock to the Raster Timing Generator PCB, used to generate the internal sync signals

Y_RGB_CONV - control signals to Convergence Deflection PCB for Red, Green, or Blue Convergence in the y-axis (full-scale correction is about 1 Vpp).

X_RGB_CONV - control signals to Convergence Deflection PCB for Red, Green, or Blue Convergence in the x-axis (full-scale correction is about 1 Vpp).

CORR_SYNC - Square wave HCT level synchronous signal to the Convergence Deflection PCB for the horizontal axis.

RGB_SHUT - Signal to operate the red, green, and blue shutters.

LENS_ZOOM - Signal to the zoom motor of the Projection Lens.

LENS_FOCUS - Signal to the focus motor of the Projector Lens.

System Controller PCB - Operation

Startup Functions

When AC Circuit Breaker is powered ON, the Low Voltage Power Supply sends +5.1 V stdby voltage to the System Controller PCB. The +5.1 V Stdby powers the CPU and IR Detector so the System Controller PCB can receive and respond to the POWER ON command. The System Controller PCB sends a /FAN_ENA signal back to the LVPS turning on the +24 V Stdby to turn the cooling fans on. When the System Controller PCB receives a POWER ON command from either the IR remote control or a PC, it sends the /LV_ENA signal to the Low Voltage Power Supply. This turns on all the non-standby (±15 V, +5.1 V, +6.2 V, +24 V, +80 V) voltages. After all the non-standby voltages power up, the LVPS sends the /LV_OK signal back to the System Controller PCB to tell it that all the non- standby voltages are present.

When the System Controller PCB receives a POWER ON command, it receives the /LAMP_OK signal from the Arc Lamp Power Supply and sends the /LAMP_ENA signal back to the Arc Lamp Power Supply to turn it on. The Arc Lamp lights, and the Arc Lamp Power Supply sends a /LAMP_LIT signal back to the System Controller PCB (see Figure 5-6).

The System Controller PCB also monitors the status of the High Voltage Power Supply through the /HV_OK signal.

5-8 Model 250 Service Manual