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16.2 Switch-on sequence.
In case of malfunction it is very important to know the switch-on procedure:
1. When the reset is at low level the microprocessor begins to work.
2. It recalls from NVM the last state before the switch-off.
3. If it is STAND BY, it remains in STAND BY. If it is ON, it continues the switch-on procedure.
4. It waits until a falling edge in the 16/9&BSYNC signal occurs.
5. The port B_HIGH is set (B_HIGH oscillating).
6. It waits until a rising edge in the 16/9&BSYNC signal occurs.
7. It reads the CTL1 signal. If this signal doesn't rise before 160mS the process is stopped indicating
ERROR_4.
8. The Video processor is started via I2C bus. If there isn't any answer the process is stopped indicating
ERROR_1.
9. There is a 1 second delay.
10. The deflections start. If there are failures the process is stopped indicating ERROR_2 or ERROR_3.
11. It waits until the cathode heater is warm by inspection of the video processor register bit AKB.
12. The picture and the sound are switched on and the procedure is finished.
16.3 Protect modes and failure indication
The microprocessor checks periodically the different parts of the circuit and if it detects any fault in a safety
defined part then it puts the TV set in PROTECTED mode. The found error code is indicated by the red LED.
The red indicator lamp flashes every 0,3 seconds and stops during 0,7 seconds. The number of flashes
depends on the error code (see table below).
The 1, 2, 5 and 6 error codes are read via the I
The 3 and 4 error codes are read through the CTL1, CTL2 and -PD&FAIL signals.
In all cases except ERROR_5 the power supply is set in SMPS_B_LOW state.
16.4 Protect mode inhibition
In order to facilitate the TV set repair it is possible to disable the protect mode. By pushing the M key (PL100)
in a fault detection situation, the microprocessor resumes normal execution flow except in ERROR_4 state
(Power Supply Short-circuit). In this case the microprocessor keeps the power supply in SMPS_B_LOW state
(the M key does not act).
16.5 Power supply repair procedure
• When it is necessary to replace the IC800, it is strongly recommended to replace also the current sensor
resistors R804 and R805 (they may be also damaged or altered).
• Keep in mind that when the power supply is forced to SMPS_B_HIGH state and without current
consumption at the main output (deflection stopped), B6 is the stabilised output. The minimum voltage
circuit is working and B6 can go down from the nominal 10 volts to 7,5 volts approximately. Also, in this
situation B1 goes up until 160 - 180 volts in TV sets with 110º CRT.
16.6 Non-volatile memory (NVM) replacement, IC125
When the TV set starts up, the microprocessor checks the non volatile memory in order to know if it has been
initialised. Even if it detects no initialisation it will continue the start up procedure with a minimum default
adjustment values stored in ROM. Then, in case of NVM replacement, it is necessary to initialise the non
volatile memory from the SERVICE menu (it will load a complete set of default values) and afterwards adjust
all the controls to its correct value.
Error indication
ERROR_1
The Video Processor does not answer
ERROR_2
Vertical Deflection Fault
ERROR_3
Horizontal Deflection Fault
ERROR_4
Power Supply Short-circuit.
ERROR_5
The Sound Processor does not answer
ERROR_6
The non volatile memory does not answer
2
Meaning
C Bus.
11
Service Manual MS CE25FN1-E
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