CIRCUIT DESCRIPTIONS
PV154 - 923-03506
3-11
ZP26/28 - SERVICING
the BUSY line. As long as the BUSY line is active, the
Main Microprocessor ignores the IR signal.
ON SCREEN DISPLAY PATH:
MICROPROCESSOR SOURCE FOR OSD:
The On Screen Display signal path is shown with the
normal OSD information such as Channel Numbers, Vol-
ume Graphic Bar, Main Menu, sent from the Main Micro-
processor to the Rainforest IC IC01 pins 37, 38 and 39.
These are positive pulses, about 5 V p/p and about 3uS
in length dependant upon their actual horizontal time
for display.
DCU SOURCE FOR OSD:
When the Service Only switch is pressed, the Main Mi-
croprocessor knows the DCU is Busy as described be-
fore. Now the On Screen Display path is from the DCU to
the Rainforest IC IC01 pins 33, 34 and 35.
The output for the DCU OSD characters is from the PDG
connector pins (11 Dig Red, 12 Dig Green and 13 Dig
Blue). These are routed through their buffers (QK06 Dig
Red, QK07 Dig Green and QK08 Dig Blue) to the PDK1
connector pins (2 Dig Red, 4 Dig Green and 5 Dig Blue)
then through their buffers, (QC24 Dig Red, QC23 Dig
Green and QC22 Dig Blue). Then it arrives at the Rainforest
IC IC01 at pins (35 Dig Red, 34 Dig Green and 33 Dig
Blue). When a character pulse arrives at any of these
pins, the internal color amp is saturated and the out-
put is generated to the CRTs. Any combination of these
inputs generates either the primary color Red, Green or
Blue or the complementary color Red and Green which
creates Yellow, Red and Blue which creates Magenta or
Green and Blue which creates Cyan.
OUTPUT STKs:
These are output amplifiers that take the correction
waveforms generated by the DCU and amplify them to
be used by the Convergence Yoke assemblies for each
color.
RV is Red Vertical Convergence correction. Adjust the
location either up or down.
RH is Red Horizontal Convergence correction. Adjust
the location either left or right.
GV is Green Vertical Convergence correction. Adjust the
location either up or down.
GH is Green Horizontal Convergence correction. Adjust
the location either left or right.
BV is Blue Vertical Convergence correction. Adjust the
location either up or down.
BH is Blue Horizontal Convergence correction. Adjust
the location either left or right.
CONVERGENCE YOKES:
Each CRT has a Deflection Yoke and a Convergence Yoke
assembly. The Deflection manipulates the beam in ac-
cordance to the waveforms produced within the Hori-
zontal Deflection circuit or the Vertical Deflection cir-
cuit. The Convergence Yoke assembly manipulates the
Beam in accordance with the correction waveforms pro-
duced by the DCU.
HD FOCUS (MAGIC FOCUS) SENSORS AND INTERFACE:
Each of the four photo cells, called solar batteries, has
its own amp which develops the DC potential produced
by the cells. Each amp is routed through the PDS1 con-
nector and arrives at the PDS connector on the DCU
where the DCU converts this DC voltage to Digital sig-
nals. These digital signals are used only when HD Focus
is activated via the Customer’s Menu and HD Focus runs.
MICROPROCESSOR:
The Microprocessor is only involved in the Digital Con-
vergence circuit related to IR (Infrared Remote Control
Signals). When the DCU is put into the Digital Conver-
gence Adjustment Mode, DCAM or HD Focus is running,
the Microprocessor ignores IR pulses. This is accom-
plished by the BUSY signal from the DCU. The BUSY sig-
nal is routed from the DCU out the PDG connector pin
10, to the PDK1 connector pin 1, then the PSD1 con-
nector pin 1 to the DAC1 I006 pin 1. Through I
2
C data
communications SCL1 and SDA1, the DAC1 IC tell the
microprocessor that the DCU is busy.
RAINFOREST IC (Video Processor):
The Rainforest IC, IC01 is only involved with the Digital
Convergence circuit related to the OSD path.
SERVICE ONLY SWITCH:
The Service Only Switch is located just in front of the
Digital Convergence Module on the Convergence PWB.
If the front speaker grill is removed and the front ac-
cess panel is opened, the switch will be on the far left
hand side. When this button is pressed with the TV ON,
the DCU enters the DCAM, (Digital Convergence Adjust-
ment Mode).
If the button is pressed and held down with the TV OFF
and the power button is pressed and released, the Digi-
tal Convergence RAM is cleared. Then, by releasing the
Service Only Switch, the DCU Grid appears. In the Cleared
RAM state, there is no influence from the DCU related to
beam deflection. Magnetic centering, Red and Blue cen-
ter offset and other adjustments requiring no influence
from the DCU are performed in this mode as well as the
ability to enter the 3X3, (9 adjustment points) mode.
ABL VOLTAGE OPERATION
The ABL voltage is generated from the ABL pin (3) of
the Flyback transformer, TH01. The ABL pull-up resistors
are RH27 and RH28. They receive their pull up voltage
from the B+ 115V2 ) line for Deflection generated from
the Power Supply via TP91 pin 11, rectified by DP15,
filtered by CP32 and then routed through the excessive
current sensing resistor RP24.
