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PIN #
DESCRIPTION
1
POWER MOSFET DRAIN
2
GROUND (HOT)
3
DRIVE (+VCC)
4
FEEDBACK (Vfb
SYNCHRONY (Vs/s
5
At the same time this voltage is also applied to an inter-
nal comparator. So the voltage of this power source must
be within a set range, between a 5VDC reference (Vref)
and a 32VDC zener diode (Vz).
This set range is verified through the UVLO (Under Volt-
age Lock Out) circuit of the Switch Power IC.
START UP
When the VCC reaches a upper threshold voltage (15
VDC) the comparator switches to enable the ICX3612
including all internal bias circuits, control circuits, PWM
modulator & Power MOSFET.
Due the demand of energy from Cst and Rst the VCC volt-
age starts to fall. Before to fall too low, a bootstrap
winding on the power transformer (pins 13 & 16) reforces
adequately the VCC power to keep the full system opera-
tion.
VOLTAGE SOURCES
There are Five secondary windings on the TX3600 and
each has its own half wave rectifier.
Consequently there are Five stand-by DC voltages: B+,
24VAUD, 21VL, 16VSB & 12VUP.
The first is used to source the horizontal sweep circuit,
HOT (Horizontal Output Transistor). The second is used
for audio. The third is exclusively for the LSP source,
which is always on stand-by. The four is used for video
low signal processing and The fifth is used for
microcontroller.
The main microprocessor IC6000 and the EAROM memory
IC6001 are supplied by a five volts stand-by source,
+5V SB, which is derived through ICX3820 (0IKE78500P).
The +16 VSB and +12 VUP volts stand-by are protected
by fuses FX3613 and FX3614 ( 4A @ 125V) Very Fast
Acting, the +21VL and +24 VAUD volts stand-by are pro-
tected by fuses FX3611 and FX3612 ( 4A @ 125V) Slow
Blow. B+ as mentioned before are protected by the OCP
circuit. So they do not need fuse.
FA - SERVICING
SERVICING (continued)
PIN DESCRIPTION
FUNCTION
To drive the chopper xfmr,capable of switching a max of 650V.
MOSFET Source connection.
Positive supply voltage, 32VDC
The output voltage error is applied to this pin.
External sync signal & Soft star capacitor.
3-2
The FA chassis can be turn it on with the keyboard on
the front of the set or with the remote hand control.
The microcontroller IC6000 receive a signal and it out-
put a high, about 4.8V, on pin 32 which is called PWR-
CTL. This pin is connected to RX3832, RX3831 and
RX3540; producing the +VAUD, +9VSW, +5VSW.
DEGAUSSING
The FA chassis employs a new method of degaussing,
which is performed through software. The IC6000 gen-
erate a pulse of about 1 second, time fixed, on pin 43.
This pin is set to high, about 4.8 VDC, through R3900,
4.7K 5% ¼watt. And it applies to Q3900, which drives
the 12 VCD relay KX3900. So the degaussing is performed
when the degauss coil is plugged to CN3T8 connector.
POWER SUPPLY ALIGNMENT PROCEDURES
ELECTRICAL ADJUSTMENT
The FA chassis SMPS does not need any manual measure-
ment. All the output voltages are regulated through
ICX3702 (221-265-03A), error amplifier. The ICX3702
keeps the regulation using a reference voltage, through
a voltage divider. The voltage divider is formed by two
precision RX3706 and RX3704.
The values of these resistors depends of the B+ output
voltage.
NOTES:
·When servicing make sure to use a 120 VAC- 60Hz 25
Amp isolated source.
·Use a full white field on the video pattern generator.
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