Philips 32PF9968/10 Service Manual page 81

Circuit Descriptions, Abbreviation List, and IC Data Sheets
Table 9-2 Pinning overview TEA1506
Pin Symbol Description
2 Vcc This pin is connected to the supply voltage. When this voltage
is high (Vcc_start level, about 11 V), the IC will start switching.
When the voltage is lower than Vcc_uvlo (about 8.7 V), the IC
will stop switching.Note: This pin is not self supplied by internal
source like in TEA1507
3 Gnd This pin is Ground of the IC.
6 Ctrl This pin is connected to the feedback loop. The pin will control
the "on" time between 1 V to 1.5 V.
7 Demag This pin is connected to the Vcc winding of 5512. It contains
three functions: 1) During magnetisation, the input voltage is
sensed to compensate OCP level for OPP, 2) During
demagnetisation, the output voltage is sensed for OVP and 3)
a comparator is used to prevent continuous conduction when
the output is overloaded.
9 Sense This pin contains three different functions: 1) dectection of soft
start, protection levels of 2) OCP, and 3) SWP.
11 Driver This pin will drive the (MOSFET) switch.
12 HVS This is High Volt Spacer (n.a.)
14 Drain Connected to the Drain of the external MOSFET switch, this is
the input for valley sensing and initial internal supply.
9.2.4 Standby Mode
In this mode, IC7511 (TEA1506) will be totally disabled. So
there is no voltage on the main transformer output. But IC7531
(TEA1523) will still work and will provide the necessary output
voltages (6V -> 5V, 3.3V, 3V -> 1.8V) to the Hercules (IC7200).
Table 9-3 PSU voltage overview
Voltage Normal operation
V_batt 143 V ± 3%
V_audio +/- 15.5 V
+12V 12 V ± 0.6V
+6V 6 V ± 0.6V
+3V 3 V ± 0.3V
Stdby_con 0 V
9.3 Deflection
9.3.1 Synchronization
After initialisation of both the UOC and the SVP, the SVP
generates both H and V sync. The TDA9332 takes care of the
deflection signals HD, VD+, VD-, E_W and HBLK.
The VD+ and VD- signals are the balanced output currents
(sawtooth shaped). These output signals are balanced, so they
are less sensitive to disturbances.
9.3.2 Horizontal Deflection
The principle of the horizontal deflection is based on a diode
modulator with east-west correction. This horizontal deflection
circuit supplies the deflection current and auxiliary voltages
from the LOT.
Basic Principle
During a scan period, either the Line Transistor or diode(s)
conduct to ensure a constant voltage over the deflection coil
(that results in a linear current). During the flyback period, the
Line Transistor stops conducting, and the flyback capacitor(s)
together with the inductance of the deflection coil creates
oscillation.
First Part of Scan
The TDA9332 (HOP) delivers the horizontal drive signal for the
Line Output stage. This signal is a square pulse of line
frequency. L5402 is the flyback drive transformer. This
transformer de-couples the line output stage from the HOP. It
Stdby mode
0 V
0 V
12 V
6 V
3 V
3.3 V
L04A AD
has a direct polarization. The flyback drive circuit works with
the start-up supply taken from +6V of the Aux supply (and
subsequently taking from VlotAux+9V). When the H-drive is
high, TS7404 conducts, and transformer L5402 starts to store
energy. The base of the line transistor TS7405 is low and
therefore blocks. The current in the deflection coil returns from
diode D6404.
Second Part of Scan
When the H-drive is low, TS7404 does not conduct, and the
energy that is stored in the transformer will transfer to the
secondary, making the base of the Line Transistor high. Then
the Line Transistor starts to conduct. The current in the
deflection coil returns from the transistor in another direction.
Flyback
At the moment the H-drive becomes high, the base of the Line
Transistor becomes low. Both the Line Transistor and the
Flyback Diode will block. There is an oscillation between the
flyback capacitor C2411 and the deflection coil. Because of the
inductance of the LOT, the Line Transistor cannot stop
conducting immediately. After the Line Transistor is out of
conduction, the flyback pulse is created. The flyback capacitor
charges until the current in the deflection coil reduce to zero.
Then it discharges through the deflection coil and the deflection
current increases from the other direction. The flyback diode
conducts and is back to the first part of the scan.
Linearity Correction
Because the deflection coil has a certain resistance, a picture
without any linearity issues cannot be expected. L5401 is the
linearity coil to compensate for this resistance. It is a coil with a
pre-magnetized core. This correction is called linearity
correction.
Horizontal S-Correction
Because the electronic beam needs to travel a longer distance
to both sides of the screen than the center, the middle of the
screen would become narrower than both sides. To prevent
this, a parabolic voltage is applied across the deflection coil
during scan. To create this parabolic voltage, a capacitor called
S-cap (C2417/C2418) is used as a voltage source during scan.
The sawtooth current of the deflection through this capacitor
creates the required parabolic voltage. This correction is called
S-Correction.
East-West Driver
The East-West parabola waveform EW_DRIVE comes from
the HOP (frame frequency) and modulates the line deflection
current.
East-West Correction
To achieve a good geometry, dynamic S-correction is needed.
The design is such that the tube/yoke needs East-West
correction. Besides that, an inner pincushion is present after
East-West correction. The line deflection is modulated with a
parabolic voltage (frame frequency). In this way it is not so
much at top and bottom, and much more in the middle.
Upon entering the picture geometry menu in the SAM mode,
the following corrections will be displayed.
• EWW: East West Width.
• EWP: East West Parabola.
• UCP: Upper Corner Parabola.
• LCP: Lower Corner Parabola.
• EWT: East West Trapezium.
The East-West drive circuit realizes them all. The settings can
be changed by a remote control. All changed data will be
stored into the NVM after the geometry alignment.
9. EN 81