Philips L01.1L AC, Service Manual

Circuit Description

EN 79

L01.1L AC

9.

9.7

Control

Figure 9-14 Block diagram set control

9.7.1

Introduction

The microprocessor part of the UOC, has the complete control 
and teletext on board. User menu, Service Default Mode, 
Service Alignment Mode and Customer Service Mode are 
generated by the uP. Communication to other ICs is done via 
the I

2

C-bus.

9.7.2

I

2

C-Bus

The main control system, which consists of the microprocessor 
part of the UOC (7200), is linked to the external devices (tuner, 
NVM, MSP, etc) by means of the I

2

C-bus. An internal I

2

C-bus 

is used to control other signal processing functions, like video 
processing, sound IF, vision IF, synchronization, etc.

9.7.3

User Interface

The 'L01.1L AC' uses a remote control with RC5 protocol. The 
incoming signal is connected to pin 67 of the UOC.
 
The 'Top Control' keyboard, connected to UOC pin 80, can also 
control the set. Button recognition is done via a voltage divider.
 
The front LED (6691) is connected to an output control line of 
the microprocessor (pin 5). It is activated to provide the user 
information about whether or not the set is working correctly 
(e.g., responding to the remote control, normal operation (USA 
only) or fault condition)

9.7.4

In- and Output Selection

For the control of the input and output selections, there are 
three lines: 
•

STATUS1. This signal provides information to the 
microprocessor on whether a video signal is available on 
the SCART1 AV input and output port (only for Europe). 
This signal is not connected in NAFTA sets.

•

STATUS2. This signal provides information to the 
microprocessor on whether a video signal is available on 
the SCART2 AV input and output port (only for Europe). 

For sets with an SVHS input it provides the additional 
information if a Y/C or CVBS source is present. The 
presence of an external Y/C source makes this line 'high' 
while a CVBS source makes the line 'low'.

•

SEL-MAIN-FRNT-RR. This is the source select control 
signal from the microprocessor. This control line is under 
user control or can be activated by the other two control 
lines.

9.7.5

Power Supply Control

The microprocessor part is supplied with 3.3 V and 3.9 V both 
derived from the 'MainAux' voltage via a 3V3 stabilizer (7560) 
and a diode.
Two signals are used to control the power supply:
•

Stdby_con. This signal is generated by the 
microprocessor when over-current takes place at the 
'MainAux' line. This is done to enable the power supply into 
standby burst mode, and to enable this mode during a 
protection. This signal is 'low' under normal operation 
conditions and goes to 'high' (3.3 V) under 'standby' and 
'fault' conditions.

•

POWER_DOWN. This signal is generated by the power 
supply. Under normal operating conditions, this signal is 
'high' (3.3 V). During 'standby' mode, this signal is a pulse 
train of approx. 10 Hz and a 'high' duration of 5 ms. It is 
used to give information to the UOC about the fault 
condition in the Audio amplifier supply circuit. This 
information is generated by sensing the current on the 
'MainAux' line (using voltage drop across R3564 to trigger 
TS7562). This signal goes 'low' when the DC-current on 
the 'MainAux' line exceeds 1.6 - 2.0 A. It is also used to give 
an early warning to the UOC about a power failure. Then 
the information is used to mute the sound amplifier to 
prevent a switch off noise and to solve the switch-off spot.

9.7.6

Protection Events

Several protection events are controlled by the UOC: 
•

BC protection, to protect the picture tube from a too high 
beam current. The UOC has the capability of measuring 
the normal back level current during the vertical flyback. So 
if for some reason the CRT circuit is malfunctioning (i.e. 
high beam current), the normal black current will be out of 
the 75 uA range, and the UOC will trigger the power supply 
to shut down. However, this is a high beam-current 
situation, the TV screen will be bright white before the set 
is shut down.

•

E/W protection, two protection mechanisms are built in, 
over-current and over-voltage. 
–

In case of over-current due to defective parts in the line 
deflection output stage, a high current will flow through 
resistors 3405//3406. If this current is large enough to 
create a voltage drop of 0.7 V across 3405//3406, 
transistor TS7606 (in A7 diagram) will conduct and pin 
80 of the UOC will be pulled down. Thereafter, the 
UOC will shut down the power supply. In case of further 
current increase, the fused resistor 3411 is built-in for 
double protection. 

–

In case of a high voltage appearing across capacitor 
2401 (dependent of the tube size), which is high 
enough to trigger zener diode 6401 into conduction, 
transistor TS7606 (in A7 diagram) will conduct and 
UOC is triggered to shut down the power supply.

•

I

2

C protection, to check whether all I

2

C ICs are 

functioning.

 
In case one of these protections is activated, the set will go into 
'standby'.
 
The 'on' and 'standby' LEDs are controlled via the UOC.

CL 16532016_015.eps

220301

Signal

Processing

User

Interface

uP - Control

LED

PANORAMA

PANORAMA

BUZZ

BASS

TREBLE/Tilt

ITV-DATA-OUT

ITV-DATA-IN

ITV-CLOCK

RESET

VOLUME/
MUTE

IR

KEYBOARD/
(EW protection

STATUS 1

STATUS 2

SEL-MAIN-FRNT-RR

internal I2C Bus

Deflection

16:9

Expansion

Slot

I/O

POWER_DOWN

STBY_CON

Power

Supply

WRITE Enable

NVM

SEL-IF-LL/M-TRAP

I2C Bus

Tuner / IF

Tilt

ITV

or

Pip

Amplifier

Processing

Sound