Sony CPD-G420 / CPD-G420S / CPD-G520 / GDM-F520 Service Manual ▷ View online
CR1 chassis (E)
5
2-6. Heater Voltage Regulator
The heater voltage regulator (IC011) generates 5V for the heater from 7V entered to the CN312 pin 7. The output voltage is
determined by the feedback from R078, 079, and 080. The 3.3V entered from CN312 pin 8 is entered to the IC011 pin 1 to control the
ON/OFF of 5V output (voltage of pin 1 3.3V: Output ON, 0V: Output OFF). The 5V output from IC001 pin 4 is sent to the pin 4 of
CRT socket (J001) through the CN315 and CN316.
2-7. E2P ROM for DDC
The E2P ROM for DDC (IC007) makes communication for DDC1 and DDC2 with the connected PC via CN307.
CR1 chassis (E)
6
3.
D BOARD
3-1. DEFLECTION CIRCUIT PART
3-1-1. Horizontal deflection circuit system block diagram (extracted)
A block diagram of horizontal deflection circuit system is shown in <Fig. 1>.
BA9759F
+B CHOP
HSAW SW
HSHAPE
HSHAPE
S6
PWM OUT
PWM NFB
HD-IN
+15V
IC501
+B
N board
DA board
FET x 7
S501
C537
Q505
C508
D504
HCC : L509
H-DY
HOC : L510
HST : T504
HDT : L501
H DRIVE
HLC : L502
LCT : T503
H LIN BAL
CONTROL
+15V
FBP
<Fig. 1>
3-1-2. Horizontal deflection circuit
Horizontal deflection is made based on horizontal drive pulses outputted from the D/A board.The size control is made by IC501 based
on the H SHAPE signal outputted from the D/A board.
This chassis uses a tap switching system by "HCC" to control the raster horizontal position. This system can change raster position only
for three positions of S501.
For the linearity control of horizontal deflection, a variable type of HLC inductance is adopted using the "LCT:T503". The inductance
of "HLC:L502" as viewed from horizontal deflection system is parallel value with the "LCT:T503". Accordingly, the inductance of
"HLC:L502" can be changed equivalently by changing L value of "LCT:T503". Also, the linearity control by the S-shaped capacitor is
performed, and 127 different values can be set with arbitrary frequencies.
3-1-3. Vertical deflection circuit system block diagram (extracted)
A block diagram of vertical deflection circuit system is shown in <Fig. 2>.
STV9379A
VSAWN
DCC2
DCC2
V-DIF+
V-DIF–
V-DIF–
+15V
IC401
–15V
DA board
V-DY
<Fig. 2>
CR1 chassis (E)
7
3-1-4. Vertical deflection circuit
Vertical deflection is made in the deflection circuit using IC401. The IC401 is a kind of power OP-AMP. The IC401 detects V-DY
winding current, and controls the V-DY winding current so that it is similar to the "VSAWN" signal outputted from the D/A board.
3-1-5. Dynamic focus
Dynamic focus is grouped into horizontal focus (HDF) and vertical focus (VDF). These control waveforms are outputted from the D/
A board, and the D board only amplifies the amplitude. The amplified focus signals are synthesized by a fly-back transformer and
become CRT focus signal.
3-1-6. Rotation amplifier: IC703
The rotation amplifier is simply a DC control AMP. It amplifies the control voltage sent from the D/A board.
3-1-7. Digital convergence drive circuit system block diagram (extracted)
A block diagram of digital convergence drive circuit system is shown in <Fig. 3>.
INPUT
+15 V
–15 V
–15 V
GND
POWER
REF POWER
ON/OFF SWITCH
REF DC
3.3 V
DIGITAL CONVERGENCE
CONTROL
CONTROL
XSC
YSC
YSC
XDC
YDC
YDC
CY
PWR SW1
3.3 V
REF DC
XDC
YDC
POWER SWITCH
XSC
YSC
POWER OP AMP
IC 701
HIGH-SPEED
POWER OP AMP
POWER OP AMP
IC 702
From DSP
XSC
YSC
YSC
XDC
YDC
YDC
<Fig. 3>
3-1-8. Digital convergence amplifier: IC701, IC702
Digital convergence drive circuit is composed of a power operational amplifier (IC701) for static convergence (XSC/YSC) and a high
speed power operational amplifier (IC702) for dynamic convergence (XDC/YDC).
These control voltages are supplied from the DSP (IC1101) mounted on the DA board. The DSP is controlled by the micro controller
through the IIC bus.
The reference voltage for static convergence is generated from 3.3 V through the resistance division.
The reference voltage for dynamic convergence is supplied from the DSP (IC1101) on the DA board.
The high speed power operational amplifier (IC702) provides a switch terminal to control the ON/OFF of convergence by the
PWR_SW1.
3-1-9. High voltage control circuit
Fundamental circuit configuration is same as conventional (such as 21G1). As a control IC, IC901 (BA9758AFS) is used.
3-1-10. G2 voltage control circuit
About 1KV reference voltage for G2 control is generated using primary winding of the fly-back transformer. The IC902 controls this
voltage to attain the G2 control voltage.
CR1 chassis (E)
8
3-2. POWER SUPPLY PART
3-2-1. SYSTEM CONFIGURATION
This system is a two-converter power supply that provides the standby 1W feature.
The system consists of total eight blocks.
"AC Filter" ... Reduces noise in the power line and limits rush current at AC power ON.
"Power Factor Improving Circuit" ... Comprises a step-up chopper circuit to improve the power factor.
It controls the voltage of AC smoothing capacitor C610 to about 370 V.
"Sub Converter" ... Supplies standby 5 V, 3.3 V, USB voltage, heater voltage, and Vcc for the "Main Converter" and "Power Factor
Improving Circuit". It operates when AC is entered.
"Main Converter" ... Outputs +B, +B2, and (15 V.
"Degauss Circuit" ... Performs degaussing by the Degauss signal from the micro controller.
"ON/OFF Circuit" ... Turns on/off the "Main Converter" and "Power Factor Improving Circuit" by the Power signal from the micro
controller.
"Standby Output Circuit" ... Outputs standby 5 V.
It controls 3.3 V by the Power signal from the micro controller.
"Heater Circuit" ... Controls the heater voltage by the Power signal from the micro controller.
The relation between each state and signals from micro controller is as listed in table.
One-stage power saving
MODE
Power SW
Sub Converter
Main Converter
Heater Voltage
Signal
& Power Factor
ImprovingCircuit
Both Hsync and Vsync
Power ON
ON
ON
ON
5 V
Either Hsync or Vsync
Active off
OFF
ON
OFF
0 V
Neither Hsync and Vsync
Active off
OFF
ON
OFF
0 V
3-2-2. OPERATIONAL DESCRIPTION OF EACH BLOCK
3-2-2-1. AC Filter
AC is entered to the CN602 from the inlet filter, and passes through the AC filter consisting of a fuse F601, C601, T601, C602, etc. and
the TH601, and then it is supplied to the rectifying circuit comprising a rectifying diode D610 and an electrolytic capacitor C610.
The power thermistor TH601 operates to limit rush current at the AC power ON.
This TH601 is shorted by RY602, and in normal operation, the current does not flow.
The RY602 operates when Vcc is supplied by the "ON/OFF Circuit" described later.
The "Sub Converter" operates when AC is supplied.
3-2-2-2. Power Factor Improving Circuit
The IC610 contains a control circuit, switching MOSFET, and diodes.
This IC610 and L610 compose a step-up chopper circuit.
The output is regulated to about 370 V and charged in the C610.
In the voltage over 250 VAC, the input voltage is higher than the output voltage, and therefore this circuit does not operate.
The OVP circuit is built in this IC. The latch stops if the output voltage exceeds 450 V.
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