Philips L04LAA, Service Manual

Circuit Descriptions, List of Abbreviations, and IC Data Sheets

EN 83

L04L AA

9.

9.2.3

Startup Sequence 

When the set is connected to the AC power, the rectified line 
voltage (via winding 4-5 of L5531 connected to pin 14 of 
IC7531) will start the internal voltage source to charge the V_cc 
capacitor (C2532). The IC starts to switch as soon as the V_cc 
reaches the V_cc start level of 9.5 V. This supply is 
automatically taken over by winding 1-2, as soon as the V_cc 
is high enough, and the internal supply source will stop (for high 
efficiency switching).

Table 9-1 Pinning overview TEA1523

As C2532 of IC7531 is charged, it will also start to charge the 
V_cc capacitor (C2511) of IC7511. Via resistor R3519 and 
C2511, the TEA1506 starts to switch as soon as the V_cc 
voltage reaches the V_cc start level of is about 11 V. The V_cc 
voltage is automatically taken over by the main transformer 
L5512 (winding 2-3) when the V_cc is high enough (when this 
voltage is even higher than the voltage on C2511, there is no 
current flow from C2532 to C2511 due to diode D6512).

Table 9-2 Pinning overview TEA1506

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

9.3

Deflection

9.3.1

Synchronization

Before the Hercules (IC7200) can generate horizontal drive 
pulses, the +3.3V supply voltages must be present.  After the 
start up command of the microprocessor (via I2C), the 
Hercules outputs the horizontal pulses. These horizontal 
pulses begin “initially” with double line frequency and then 
change “gradually” to line frequency in order to limit the current 
in the line stage (slow-start).
 
The VDRA and VDRB signals are the balanced output currents 
(sawtooth shaped) of the frame oscillator (pins 106 and 107 of 
the Hercules). These output signals are balanced, so they are 
less sensitive to disturbances.
 
There is a current source inside the UOC at pin 102. This 
pumps energy in the capacitor connected to this pin producing 
a pure saw tooth. The vertical drive signals and the E/W 
correction signal are derived.
 
Pin 108 is the East-West drive (or AVL), and it is a single ended 
current output. The correction for “horizontal width for changed 
EHT” from this pin is available by setting the HCO bit to “1”.  
 
The Phase-2 Compensation available at pin 113 gives frame 
correction for high beam currents. The phase compensation 
signal is used to correct the phase of the picture from the 
horizontal drive signal.
 
Pin 63 is the SANDCASTLE output (contains all sync info) and 
also HORIZONTAL FLYBACK (HFB) input.
Pin 97 is the EHT tracking/over-voltage protection pin. The 
HCO bit can switch on the tracking on EW. If the voltage at pin 
97 exceeds 3.9 V, the over-voltage protection will be activated 
and the horizontal drive is switched “off” via a slow stop.

9.3.2

Horizontal Deflection

There are several executions (depending on the CRT): 

•

Sets with no East-West correction. The principle of the 
horizontal deflection is based on the quasi-diode 
modulation circuit. This horizontal deflection circuit 
supplies the deflection current and auxiliary voltages from 
the LOT.

•

Sets with East-West correction. 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.

•

Sets with dynamic East-West correction. The principle 
of the horizontal deflection is based on a diode modulator 
with dynamic east-west correction for picture tubes with 
inner pincushion. 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.

Pin

Symbol

Description

2

Gnd

This pin is Ground of the IC.

3

V_cc

This pin is connected to the supply voltage. An internal current 
charges the V_cc capacitor (2532), and the start-up sequence 
is initiated when this voltage reaches a level of 9.5 V. Note: The 
output power is disabled when the voltage gets below 9 V 
(UVLO). Operating range is between 0 to 40 V.

5

RC

Frequency setting 

6

REG

This pin is connected to the feedback loop. The pin contains two 
functions: 1) Between 1 to 1.425 V it controls the "on" time. 2) 
Above the threshold of 3.5 V, it is possible to initiate "burst 
mode" standby.

11

Demag

This pin is connected to the V_cc winding of 5531. It has 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 output is 
overloaded.

12

Sense

This pin contains three  different functions.: 1) Dectection of soft 
start, protection levels of 2) OCP, and 3) SWP.

14

Drain

This pin is connected to the drain of the switch or center tap of 
the transformer. It contains three functions: 1) M-level (mains-
dependent operation-enabling level), 2) Supply for start-up 
current, and 3) Valley detection.

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.

Voltage

Normal operation

Stdby  mode

V_batt

130 - 143 V

0 V

V_audio

+/- 15.5 V

0 V

+6V

6 V

6 V

+3V

3 V

3 V

Stdby_con

0 V

3.3 V