Philips 42FD9932 - annexe 2 Service Manual Download

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Service modes, fault finding and repair tips

GB 14

FTV1.9DE

5.5

The "blinking LED" procedure

The contents of the error buffer can also be made visible
through the "blinking LED" procedure. This is especially useful
when there is no picture. There are two methods:
•

When the SDM is entered, the LED will blink the contents
of the error-buffer. Error-codes = 10 are shown as followed.
A long blink of 1second which is an indication of the
decimal digit, followed by a pause, followed by n short
blinks. When all the error-codes are displayed, the
sequence is finished with a led display of about 3 seconds.
The sequence starts again.

•

With the DST all error codes in the error buffer can be
made visible. Transmit the command: "DIAGNOSE x OK"
where x is the position in the error buffer to be made visible
x ranges from 1, (the last (actual) error) to 10 (the first
error). The LED will operate in the same way as in the
previous point, but now for the error code on position x.

Example:
Error code position 1 2 3 4 5
Error buffer: 12 9 5 0 0
•

after entering SDM: 1 long blink of 1 sec. + 2 short blinks
- pause - 9 short blinks - pause - 5 short blinks - pause -
long blink of 3 sec. --etc.

•

after transmitting "DIAGNOSE- 1- OK" with the DST: 1 long
blink 2 short blinks - pause - 1 long blink + 2 short blinks
- etc.

•

after transmitting "DIAGNOSE- 2- OK" with the DST: blink
(9x) - pause - blink (9x) - etc.

•

after transmitting "DIAGNOSE- 3- OK" with the DST: blink
(5x) - pause - blink (5x) - etc.

•

after transmitting "DIAGNOSE- 4- OK" with the DST:
nothing happens

5.6

Protection structure

5.6.1

General

The protection structure of the FTV1.9 D-box is shown at figure
5.5.
The FTV1.9 monitor has one microprocessor, which is situated
on the AV-control panel and is supplied by the 5V standby
supply. The microprocessor is even active when the set is
switched to standby. The microprocessor controls the "supply-
on" line which switches first relay 5680 and then relay 5690.
In de standby-mode or the protection-mode the "supply-on" line
is "low" and both relays are switched off. The preconditioner is
disconnected from the mains.
The protections of the FTV1.9 monitor can be divided into 5
subgroups:
–

Fan_prot

–

Over_temp_prot

–

DC_prot

–

Over_voltage_prot

–

Vrr

For the Fan-, Over_temp, DC and the Over_voltage protections
the signals for the

P are latching, using the 5Vstby_switched

for powering the circuits permanently. The

P has sufficient

time for diagnosis and for storing the error-codes in the NVM.
Vrr, which is an indication of the powersupply of the display is
correct, is directly fed to the

5.6.2

Signal line "PROTECTION STATUS" and errorcodes

When one of the protection mechanism is triggered, the
5Vstby-switched is connected via a saturated transistor and a
pre-defined resistor to signal line "protection status", which is
connected to the

Signal line "protection status" is connected to ground via
resistor R3378 and 3379. For each separate fault condition
mechanism we get a pre-defined voltage at the

µΠ

This results in the following table

Protection signal Vrr coming from the PDP, to indicate that the
powersupply is ok or not ok ( "1" or "0" ) is directly connected
to the

P. Error-code 7 is stored in the NVM and the set is

switched to standby.
When one of the protections is activated, the power supplies of
the Vs and Va are shut down and the set is switched to
standby.

5.6.3

Fan protection

When this protection is activated, the Va- and Vs power supply
are shut down. The set is switched to the standby mode and
error-code 3 is stored in the NVM.
The fan voltage is powered by 17V, but clamped to 12V to
prevent damage. In order to be able to verify whether the fans
are running, a fault detection circuit is implemented for each of
the 6 fans. A running fan gives pulses in the same speed as the
rotation of the blades. The circuit uses these pulses to trigger
the discharge of an elcap. The elcap is continuously charged
through a resistor.
Example : Capacitor C2319 is charged through R3356 and at
every pulse discharged by T7322. When fan 6 is blocked,
C2314 is charged via D6326 en triggers thyristor 7315,
because C2319 is no longer discharged via T7322. The current
now flows from the 5Vstby-switched via resistor 3383 and 3325
driving transistor T7321 into saturation. The voltage dividing of
R3323 and resistor R3378 and 3379 now determine the
voltage "protection status". (neglect the Vce of 0.2V of T7321.).

Reset of the VsVa-supply.
Transistor T7339 is shorted now by the presence of the
"protection status" signal. T7339 connects resistor R3376 and
R3389 to ground, switching on T7338. Thyristor 7333 is now
triggered, shorting signal PROTS to ground. To follow the
signal flow, go to the right upper corner of schematic FD1.
Connecting PROTS to ground, will start a current flow through
opto-coupler diode 7103 and the opto-coupler transistor
connects supply voltage Vcc2 to the fault input ( pin 10 ) of IC
7101. When the voltage at pin 10 exceeds 1.0V, IC7101 stops
oscillating. The Va-supply stops functioning.
To continue the signal flow, go to the right upper corner of
schematic FD2. Connecting PROTS to ground also results in a
current flow through the opto-coupler diode of 7003. The opto-
coupler transistor connects supply voltage Vcc1 to the fault
input ( pin 10 ) of IC 7001. When the voltage at pin 10 exceeds
1.0V, IC7001 stops oscillating. The Vs-supply stops
functioning.