JVC 250 Service Manual page 73

Chapter 5---Electronics
IIC_CLK - IIC clock line. Unidirectional clock line for control of synchronous
data transfer over the IIC bus.
IIC_DATA - IIC data line. Bi-directional serial line for synchronous data transfer
between System Controller PCB and Raster Timing Generator PCB.
+15 V (two inputs) - input power from LVPS for analog circuitry including the
Phase Lock Loop (PLL) circuit.
-15 V (two inputs) - input power from LVPS for analog circuitry including the
Phase Lock Loop (PLL) circuit.
+5.1 V - input power from the LVPS for digital circuitry
Raster Timing Generator PCB - Outputs
SOURCE_VALID - signal to the System Controller PCB, indicates a new or valid
source. High = valid, stable source, low = change in input source.
ODD_FIELD - square wave to System Controller PCB, with 50% duty cycle that
is high during the odd field of an interlaced signal and low for non-interlaced
signals.
280_CLK - square wave to System Controller PCB, with 50% duty cycle,
synchronized to the horizontal sync at 280 times the frequency of the horizontal
sync. This signal is used by the System Controller PCB to properly output shading
and convergence data.
CLAMP - a negative-going image clamp signal to the Video Processor PCB, with
about 3% duty cycle.
BLANKING - right, left, top, and bottom blanking signal to the Video Processor
PCB.
H_BAND(0-3) - horizontal frequency band lines to the Horizontal Vertical
Deflection PCB.
Band 0 = 15 - 24 kHz
Band 1 = 24 - 28 kHz
Band 2 = 28 - 55 kHz
Band 3 = 56 - 90 kHz
/H_ENA - enables the horizontal deflection amplifier on the Horizontal Vertical
Deflection PCB, Low = enabled deflection; high = disabled deflection.
H_FV2 - a DC voltage to the Horizontal Vertical Deflection PCB and System
Controller PCB, proportional to horizontal frequency.
H_DRIVE - square wave to the Horizontal Vertical Deflection PCB, 50% duty
cycle synchronized to the selected horizontal sync. This signal provides a sample
of the horizontal sync to the horizontal amplifier on the Horizontal Vertical
Deflection PCB.
HVPS_SYNC - synchronization pulse for High Voltage Power Supply,
synchronized with the selected horizontal sync at the same, half, or one third the
frequency.
5-18 Model 250 Service Manual