Service manual

PV152 3-6 PROJO
CIRCUIT DESCRIPTION
DAC1 I003 and DAC2 I004:
These Digital to Analog converter acts as an extensions of
the Microprocessor( Sometimes called an Expansion ICs).
The purpose of these ICs are to reduce the number of pins,
(fan out) of the Main Microprocessor I001. The Main Mi-
croprocessor send Clock and Data via I2C bus to the DAC1
IC. The output from the Microprocessor is pin (2 SDA1 and
3 SCL1) which arrives at the DAC1 and DAC2 ICs at pins (5
and 6) respectively.
Level Shift I014:
The Microprocessor operates at 3.3VDC. Most of the Cir-
cuits controlled by the Microprocessor operate at 5VDC.
The Level Shift IC steps up the DC voltage to accommo-
date.
ON THE DEFLECTION PWB:
Sweep Control I701:
The Sweep Control IC is responsible for generating Hori-
zontal Drive and Vertical Drive signals. The Microprocessor
must tell the IC when certain things are done in the Ser-
vice Menu. When Cut Off is performed, the Vertical is col-
lapsed. The Microprocessor tells I701 to stop producing
Vertical Drive. At the same time, I701 must stop the Spot
Killer circuit from operating. This is accomplished by plac-
ing pin (24 DAC3) high which activates QN07 which inhib-
its spot killer high. Also, when H.Phase is adjusted, the
Microprocessor controls the H. Drive signals phase in rela-
tionship to H.Blk which is timed with video sync. This
gives the appearance that the horizontal centering is be-
ing moved. Communication from the Microprocessor via
pins (59 SDA2 and 60 SCL2) to the PSD2 connector pins (2
and 3) and then to I701 pins (16 and 17) respectively.
ON THE SUB VIDEO PWB (2H VIDEO):
Jungle IX01:
The Video Processing IC is responsible for controlling video/
chroma processing before the signal is made available to
the CRTs. Some of the emphasis circuits are controlled by
the customer’s menu. As well as some of them being con-
trolled by AI, (Artificial Intelligence). Communication from
the Microprocessor via pins (59 SDA2 and 60 SCL2) to the
PSZ2 connector pins (1 and 2) and then to IX01 pins (27
and 26) respectively.
MICROPROCESSOR AS THE SOURCE FOR OSD:
The Microprocessor receives information related to timing
for H. Blanking and V. Blanking. These arrive at pins (49
and 55) respectively. The Microprocessor determines the
position for each display using these signals as a timing
pulse. When it’s necessary, the Microprocessor generates
1uSec pulses from pins (37 Red, 38 Green and 39 Blue)
that are routed through the PSZ1 connector pins (14 Red,
16 Green and 18 Blue) and then through (QX07 Red, QX08
Green and QX09 Blue) and then sent to the Jungle IC IX01
pins (39 Red, 38 Green and 37 Blue) as OSD signals. When
the OSD signals are high, they turn on the output of the
Red or Green or Blue chroma amps inside the jungle IC and
output a pulse to the CRTs to generate that particular char-
acter in the particular color. HALF TONE PIN (40): This pin
is responsible for controlling the background transparency
of the Main Menu. When the customer calls up the Main
Menu, they can select the CUSTOM section. Within the
CUSTOM section is MENU BACK-GROUND. There are three
selections for this, GRAY, SHADED, and CLEAR. · CLEAR:
Selection turns off any background for the Menu and video
is clearly seen behind the Menu. · SHADED: Selection add a
transparent background which makes the Menu easier to
see and also some of the video behind the Menu. · GRAY:
Selection generates a GRAY background for the MENU block-
ing video behind the Menu. This is accomplished by out-
putting any one of three different pulses from pin (40) of
the Microprocessor. This signal is then routed through the
PSZ1 connector pin (20) to the jungle IC IX01 pin (47) as
YM signal which does the following: · CLEAR: No output
during the display of the Menu. · SHADED: 1/2 Vcc pulse
equal to the timing of the Menu background. · GRAY: Full
Vcc equal to the timing of the Menu background.
OSD BLANKING PIN (51):
This pin is responsible for muting the video behind each
character produced by the Microprocessor. This pulse is in
exact time with the character, however it is slightly longer.
In other words, just before any character is produced, this
pin goes high and just after any character turns off, this
pin turns off. This clears up the video behind the OSD
character to make it easier to read. OSD Blk is produced
from pin (51) of the Microprocessor. This signal is then
routed through Q013, then through Q007, through the
PSZ1 connector pin (19) to the jungle IC IX01 pin (36) as
YS1 signal which mutes the video.
P Blk PICTURE BLANKING PIN (56):
This pin is responsible for muting the video when the Mi-
croprocessor deems it necessary. This would be during power
up or power off, child lock, channel change, or selecting a
video input with no video input available. P Blk is pro-
duced from pin (56) of the Microprocessor. This signal is
then routed through Q007, through the PSZ1 connector
pin (19) to the Jungle IC IX01 pin (36) as YS1 signal which
mutes the video.