Philips FTP1.1E Service Manual page 27

There are several types of protections:
•
I2C related protections.
•
OTC related protections (via polling on I/O pins or via
algorithms).
•
Hardware protection
All protections are explained below.
5.7.2
I2C Related Protections
In normal operation, some registers of the I2C controlled ICs
are refreshed every 200 ms. During this sequence, the I2C
busses and the I2C ICs are checked.
An I2C protection will take place if the SDA and SCL lines are
short-circuited to ground, or to each other. An I2C error will also
occur, if the power supply of the IC is missing.
3V3_PDP protection: When the 3V3 supply is short-circuited
or interrupted the set switches off and goes into protection. The
FBX, EPLD IC and 3D comb (US only) have no supply voltage
and give no acknowledge. In this case the set should go into
protection. An error code is written in the NVM: 3V3_PDP error.
FBX protection: the FBX protection is not available anymore.
5.7.3
OTC Related Protections
If a protection is detected at an OTC input, the OTC will start to
scan all protection inputs every 200 ms for 5 times. If the
protection on one of the inputs is still active after 1 s, the
microprocessor will put the set in the protection mode. Before
the scanning is started, a so-called "ESD refresh" is carried out.
This is done, because the interrupt on one of the inputs is
possibly caused either by a flash or by ESD. As a flash or ESD
can influence IC settings, the HIP, MSP, 3D Comb (US only)
and wireless module (not used in this set) are initialised again,
to ensure the normal picture and sound conditions of the set.
8 V and 5 V protections: The microprocessor senses the
presence of the 8 V and 5 V (via the "+5V_CON" and
"+8V_CON" lines). If one (or both) of these voltages is (are) not
present, an error code is stored in the error buffer of the NVM,
and the set is put in the protection mode.
Audio DC protection: The OTC senses if the audio module is
in protection via IRQ-DIGITAL (pin 98 of OTC). If this is the
case, the OTC puts the set in protection.
5.7.4
Hardware Protection
Short-circuiting the 3V3 supply from the PDP will bring the TV
in protection mode. The absence of the 3V3 supply line is also
sensed via I2C and will be mentioned in the error overview.
5.8
Repair tips
5.8.1
3V3 Supply
As mentioned above, the 3V3 supply is switched "off" when
something goes wrong (detection of a missing 3V3 supply at
one of the devices supplied by the 3V3). Because of this, the
set goes to protection (I2C protection). Error code 55 is logged.
For further diagnoses of the SSB, you need to overrule the I2C
protection: put the set in Service Default Mode by means of the
solder pads on the SSB. Connect an external 3V3 supply at
connector 1Y81 (B20) and make sure the current is limited to
approximately 1200 mA. If the supplied current exceeds 1100
mA (approximately normal working current) you can conclude
that one of the devices supplied by 3V3 is short-circuited on the
SSB. If the current does not exceed 1100mA the supply of the
PDP is defective.
Service Modes, Error Codes, and Fault Finding FTP1.1E
5.8.2
ComPair
This chassis does not have an IR transmitting LED (as in MG-
sets). Therefore, a "Service" (ComPair) connector is
implemented at the rear side of the set, which is directly
accessible (as in A10-, EM2E-, EM3E and EM5E-sets). In
addition to this, there is also a blinking LED procedure to show
the contents of the error buffer.
When you use ComPair, you have the possibility to activate a
"stepwise start-up" mode. With this mode, you can initiate the
start-up sequence step by step. This also means that in certain
steps, some protections are not activated. This is sometimes
very convenient during repair.
5.8.3
Protections
Activating SDM via the "service pads" will overrule the
processor-controlled protections, but not the hardware
protections. This means, that the A/D-input protections (5 and
8 V) and the I2C "not-acknowledging" info of FBX + EPLD + 3D
Comb (US) and of the tuner are overruled.
Caution: When doing this, the service technician must know
what he is doing, as it could lead to damaging the set.
5.8.4
Power Supply
The power supply is part of the PDP display which is not
described in this manual. However for normal operation at least
+9V-STBY and +9V-STBY-SW must be available, both are
available on connector 1Y82 of SSB. When this is valid the
standby voltage +5V2-DISP must be available otherwise OTC
is not powered.
5. EN 27