EN 689.L01.1E ABCircuit Description
EHT varies dependent of the beam current). This correction is
derived from the ?EHTinformation? line.
Two protections are built-in for the E/W circuit: over-current and VCC1SUPPLYMANAGEMENTSTART-UPCURRENT SOURCE8DRAIN
clampHVS
over-voltage protection. See paragraph Power Supply.internalUVLO start7n.c.
supplyVALLEY
M-level
S14
GND2VOLTAGECONTROLLEDLOGICDEM
OSCILLATOR
Panorama100 mV
The panorama function is only used in 16:9 sets. This is a OVER-
FREQUENCYVOLTAGE
function to enable the 4:3 and Super-Wide feature. It drives the CONTROLPROTECTION
?Bass_panorama? line, to activate relay 1400. When this relay OVER-LOGICDRIVER6DRIVER
TEMPERATURE
is switched on, the capacitors 2453//2454 are added in parallel PROTECTIONI
3ss
to the default S-correction capacitors 2456//2457. This results CTRL-1POWER-ONRESETSQLEBsoft0.5 V
blankstart
in an increased capacitance, a lower resonance frequency of S2UVLORQ
2.5 V5I
the line deflection coil and the S-correction capacitors and burstOCPsense
detect
therefore a less steep S-corrected line deflection current.
MAXIMUMshortwinding0.75 V
ON-TIME
TEA1507OVERPOWERPROTECTION
9.5.4 Rotation (only present in widescreen sets)PROTECTION
CL 16532020_073.eps
060701
To cope with the different earth magnetism situations in the
world, a rotation coil is added in widescreen sets. This coil is
Figure 9-7
controlled by the rotation circuitry (see diagram A15).
The amount of frame rotation is user controlled via the the
9.6.1 Introduction
PWM output (pin 77) of the UOC.
With the tilt setting at ?-10?, the PWM duty cycle is 0.1 (leftmost
tuning). The supply is a Switching Mode Power Supply (SMPS). The
With the setting at ?+10?, the duty cycle is 0.9 (rightmost tuning). frequency of operation varies with the circuit load. This ?Quasi-
The output of amplifier IC7171 is a DC-voltage in the range Resonant Flyback? behaviour has some important benefits
from 0 (user setting = -10), via 6 V (user setting = 0) to 12 V compared to a ?hard switching? fixed frequency Flyback
(user setting = +10).converter. The efficiency can be improved up to 90%, which
results in lower power consumption. Moreover the supply runs
cooler and safety is enhanced.
9.6Power Supply The power supply starts operating when a DC voltage goes
from the rectifier bridge via T5520, R3532 to pin 8. The
operating voltage for the driver circuit is also taken from the
VLINE
?hot? side of this transformer.
VINVOUTThe switching regulator IC7520 starts switching the FET ?on?
and ?off?, to control the current flow through the primary winding
INC
NPof transformer 5520. The energy stored in the primary winding
SN
during the ?on? time is delivered to the secondary windings
VCCduring the ?off? time.
TEA1507
The ?MainSupply? line is the reference voltage for the power
1VccDrain8
CD
2GndHVS 7supply. It is sampled by resistors 3543 and 3544 and fed to the
3CtrlDriver 6input of the regulator 7540/6540. This regulator drives the
C
4 DemagSense 5feedback optocoupler 7515 to set the feedback control voltage SS
RSSRSENSE
on pin 3 of 7520.
The power supply in the set is ?on? any time AC power goes to
the set.
NVcc
Derived Voltages
The voltages supplied by the secondary windings of T5520 are:
?MainAux? for the audio circuit (voltage depends on set
execution, see table below),
3.3 V and 3.9 V for the microprocessor and
?MainSupply? for the horizontal output (voltage depends on
set execution, see table below).
CL 16532020_074.epsOther supply voltages are provided by the LOT. It supplies +50
120401
V (only for large screen sets), +13 V, +8 V, +5 V and a +200 V
source for the video drive. The secondary voltages of the LOT
Figure 9-6
are monitored by the ?EHTinformation? lines. These lines are
fed to the video processor part of the UOC IC7200 on pins 11
and 34.
This circuit will shut ?off? the horizontal drive in case of over-
voltage or excessive beam current. |
ACEC
