5
Faultfinding tree & Repair facilities
8
L7.3A
5.1
Repair facilities
5.2
Functional blocks
The PCB has service printing on both sides , so on the copper
and the component side. Functional blocks are indicated by
lines and text.
Test points are referring to the functional blocks as mentioned
above :
–
Test pointElectrical function
–
P1, P2, etc. :Power supply
–
L1, L2, etc. :Line drive and line output
–
F1, F2, etc. :Frame drive and frame output
–
S1, S2, etc. :Synchronization
–
V1, V2, etc.: Video
–
A1, A2, etc.: Audio
–
C1, C2, etc.:Control
–
B1, B2, etc : BTSC stereo decoding
–
N1, N2, etc.:NICAM stereo decoding
The numbering is done in for a diagnostics logical sequence.
Example: Checking the power supply, start with test point P1,
P2 etc.
5.3
Service mode
The service mode is a pre-defined mode which can be used for
faultfinding and adjustments (especially when the TV gives no
picture at all you can use the service default mode). All
oscillograms and DC voltages in this service manual are
measured in the service default mode.
The service mode is split into two parts :
•
Service Default Mode (SDM).
•
Service Alignment Mode (SAM).
SDM. In the service default mode you are able to carry out
(hardware) measurements under pre-defined conditions. To
entry the (SDM) Service Default Mode there are two
possibilities:
•
Via the "DEFAULT" button on the Dealer Service Tool,
service codenumber : 4822 218 21232.
•
Via Short-circuiting the service pins M24 and M25 on PCB
and switching on the set via the mains switch. For M25 and
M24 see Diagram A4 and the PWB drawing of the main
panel
In the SDM mode a "S" (in green) and the menu (in red) is
displayed (see Fig. 1).
SAM. In the SAM mode you are able to align/adjust settings via
menu selection. To entry the (SAM) Service Alignment Mode
there are two possibilities :
•
Via the "ALIGN" button on the Dealer Service Tool
•
Via Short-circuiting service pins M28 and M29 on PCB and
switching on the set via the mains switch. For M25 and
M24 see Diagram A4 and the PWB drawing of the main
panel
In the SAM mode a "S" (in green) and the menu (in red) is
displayed (see Fig. 2).
REMARKS: After the set is in the service mode the short circuit
can be removed.
To leave the Service mode press the stand-by button on the
remote control.
REMARKS : After switching off and on the mains switch, the
set remains in the service mode (SDM- or SAM mode).
Features are :
•
Service settings after entry
•
Service (sub) menu selection
•
Error buffer display
•
Software version and identification display
•
Life timer (run timer) display
•
Option bytes
5.4
Initial states
The initial state after switching on in service mode for System
and Tuning are as follows :
•
For Multi-System sets PAL BG/SECAM/DK/NTSC
•
For Bi-Norma and Tri-Norma sets NTSC/PAL-M/PAL-N
•
For sets with VST tuning : Programme number 1 is
selected and the system will be tuned at the tuning data (for
programme 1) read from EEPROM
•
For sets with PLL tuning : Set is tuned to a frequency of
475.25 MHz.
Further settings :
•
The automatic switch off (no IDENT) timer and the sleep
timer will be ignored
•
The child lock will be disabled.
•
If the TV sets was in hotel mode, this mode will be disabled
as long as the TV is in service mode.
•
Brightness, saturation, sharpness, contrast and balance
are initialised to 50% level.
•
The volume is set to 25% level.
•
The TV is normally controllable.
•
All displayed text strings in service mode, so SDM and
SAM mode will be displayed in the English language.
Other features
RAM test of the uP (=IC7600) and the NV RAM (=IC7620). At
every start-up of the TV, a read after write test for the complete
RAM of IC7600 and via I2C the NVRAM (=IC7620) will be
performed. If this check fails, the appropriate error number will
be written in the error buffer. The patterns will be chosen in
such a way that every bit of all bytes, will be written high and
low. If the NVRAM is empty default values will be loaded.
5.5
SDM (Service Default Mode)
This menu is being displayed whenever SDM is entered. In this
menu the error buffer can be inspected, and the option byte(s)
can be (re)programmed. The overview of the menu is shown
below :
The MENU UP/DOWN command can be used to select the
next/ previous option ; the MENU LEFT/RIGHT command can
be used to change the option value.
S (Service mode)
L73AP21 1.0
(Software version)
9999 (Life timer)
