Theory of Operation
TSG 95 Service Manual
3–3
applies 0.2315 times VIN to the ADC input. The ADC reference voltage is 2.5 V
from (U20, A1
<
3
>
).
Another ADC input is used to monitor the ON key. Power is turned on by the
hardware without
m
P interaction; however, power is always turned off by the
m
P.
When the ON key is pressed, VIN is applied to the gate of Q2, which is normally
pulled down by R30. This causes Q2 to pull the input of the ADC down which is
normally pulled to +5 V through R2.
The MODE0, MODE1, STOP, and NMI pins are pulled up by R2.
The LCD is controlled by the microprocessor (U2) through connector J1, which
serves as a 4-bit data bus (UPD3..0) and control lines LCDE, LCDR/W, and
LCDRS. LCDE enables the LCD interface; LCDR/W selects whether a read or
write operation is being performed; and LCDRS selects whether an instruction or
data is being sent to the LCD.
R1 and R25 set the display contrast.
The LCD backlight power is applied through J6 by Q1 and R26. The on resis-
tance of Q1 and R26 sets the amount of current, and therefore brightness, of the
backlight.
Character generation is performed by the ASIC (U26). The character information
is loaded into U26 by the microprocessor (
m
P, U2).
The 27 MHz, temperature-compensated oscillator (TCXO) Y1 is the source of all
clocks in the system. U21 is used to buffer the output of the oscillator. The buff-
ered clock drives only the ASIC (U26). The ASIC generates a divide-by-two
clock (UPCLK) and its complement (UPCLK) to act as the clock for the
m
P. The
ASIC also generates a divide-by-eight clock (AUDCLK) for the tone chip (U12).
The DAC (U14, A1
<
3
>
) is driven by a delayed version of the 27 MHz clock.
The heart of the digital timing and signal generation is an ASIC (U26); see sche-
matic A1
<
2
>
. This chip generates addresses for the signal memory (U5 & U7),
processes data from that memory, generates characters, latches and decodes
m
P
addresses, acts as a
m
P interface, and generates a clock for the tone chip (U12,
A1
<
3
>
).
The test signals are broken down into eight point data segments. These segments
are stored in the RAM (U5). The eight segments are put together to form the test
signal. The ASIC gets the information to form video lines and frames from U7.
The lower four address lines of U5 are constantly addressed by the lower four
bits of the YC/horizontal counter. Counting off Cb, Y, Cr, Y to form eight points
of Y data in segments of multiplexed Y and C data. The lsb does the toggling
between Y and C data, while the next three bits count off the eight points.
LCD Display
Character Generation
Clock Generation
Digital Timing and
Signal Generation
Содержание TSG 95
Страница 4: ......
Страница 6: ...TSG 95 Service Manual...
Страница 14: ...Service Safety Summary viii TSG 95 Service Manual...
Страница 29: ...Specifications TSG 95 Service Manual 1 15 Figure 1 3 PAL 75 Red and Red Field Figure 1 4 PAL 100 Red...
Страница 30: ...Specifications 1 16 TSG 95 Service Manual Figure 1 5 PAL Green Field Figure 1 6 PAL Blue Field...
Страница 31: ...Specifications TSG 95 Service Manual 1 17 Figure 1 7 PAL 50 Flat Field Figure 1 8 PAL 100 Flat Field...
Страница 34: ...Specifications 1 20 TSG 95 Service Manual Figure 1 13 PAL Modulated 5 Step Figure 1 14 PAL Multiburst...
Страница 35: ...Specifications TSG 95 Service Manual 1 21 Figure 1 15 PAL Reduced Sweep Figure 1 16 PAL Pluge...
Страница 40: ...Specifications 1 26 TSG 95 Service Manual Figure 1 25 PAL Matrix Signal UK ITS 2...
Страница 41: ...Specifications TSG 95 Service Manual 1 27 Figure 1 26 PAL Safe Area...
Страница 42: ...Specifications 1 28 TSG 95 Service Manual NTSC Waveform Diagrams Figure 1 27 SMPTE NTSC Color Bar Components...
Страница 43: ...Specifications TSG 95 Service Manual 1 29 Figure 1 28 SMPTE NTSC Color Bars Zero Setup...
Страница 45: ...Specifications TSG 95 Service Manual 1 31 Figure 1 31 NTSC Red Field Figure 1 32 NTSC Red Field Zero Setup...
Страница 46: ...Specifications 1 32 TSG 95 Service Manual Figure 1 33 NTSC Sin x x Figure 1 34 NTSC 5 Step Staircase Gray Scale...
Страница 50: ...Specifications 1 36 TSG 95 Service Manual Figure 1 41 NTSC Convergence Components...
Страница 51: ...Specifications TSG 95 Service Manual 1 37 Figure 1 42 NTC7 NTSC Composite Figure 1 43 NTC7 NTSC Combination...
Страница 52: ...Specifications 1 38 TSG 95 Service Manual Figure 1 44 FCC NTSC Composite Figure 1 45 NTSC Cable Multiburst...
Страница 53: ...Specifications TSG 95 Service Manual 1 39 Figure 1 46 NTSC Cable Sweep Figure 1 47 NTSC Matrix...
Страница 54: ...Specifications 1 40 TSG 95 Service Manual Figure 1 48 NTSC Safe Area...
Страница 104: ...Performance Verification and Adjustment Procedures 4 30 TSG 95 Service Manual...
Страница 118: ...Maintenance 5 14 TSG 95 Service Manual...
Страница 134: ...TSG 95 Service Manual 7 8...
Страница 139: ...Replaceable Mechanical Parts 8 5 TSG 95 Service Manual A1 A2 A3 Figure 1 Exploded View...
Страница 140: ...Replaceable Mechanical Parts 8 6 TSG 95 Service Manual...