The Blinking Led Procedure; Repair Tips - Philips 29PT5445/85 Service Manual

Service Modes, Error Codes, and Fault Finding
3. ComPair speeds up the repair time since it can
automatically communicate with the chassis (when the
microprocessor is working) and all repair information is
directly available. When ComPair is installed together with
the Force/SearchMan electronic manual of the defective
chassis, schematics and PWBs are only a mouse click
away.
Specifications
ComPair consists of a Windows based fault finding program
and an interface box between PC and the (defective) product.
The ComPair interface box is connected to the PC via a serial
(or RS-232) cable.
For this chassis, the ComPair interface box and the TV
communicate via a bi-directional service cable via the service
connector(s).
The ComPair fault finding program is able to determine the
problem of the defective television. ComPair can gather
diagnostic information in two ways:
• Automatically (by communicating with the television):
ComPair can automatically read out the contents of the
entire error buffer. Diagnosis is done on I
2
ComPair can access the I
ComPair can send and receive I
the microcontroller of the television. In this way, it is
possible for ComPair to communicate (read and write) to
2
devices on the I C/UART buses of the TV-set.
• Manually (by asking questions to you): Automatic
diagnosis is only possible if the microcontroller of the
television is working correctly and only to a certain extent.
When this is not the case, ComPair will guide you through
the fault finding tree by asking you questions (e.g. Does the
screen give a picture? Click on the correct answer: YES /
NO) and showing you examples (e.g. Measure test-point I7
and click on the correct oscillogram you see on the
oscilloscope). You can answer by clicking on a link (e.g.
text or a waveform picture) that will bring you to the next
step in the fault finding process.
By a combination of automatic diagnostics and an interactive
question / answer procedure, ComPair will enable you to find
most problems in a fast and effective way.
How to Connect
This is described in the chassis fault finding database in
ComPair.
Caution: It is compulsory to connect the TV to the PC as
shown in the picture below (with the ComPair interface in
between), as the ComPair interface acts as a level shifter. If
one connects the TV directly to the PC (via UART), ICs will be
blown!
UART SERVICE
CONNECTOR
Figure 5-2 ComPair interface connection
How to Order
ComPair order codes (US):
• ComPair Software: ST4191.
• ComPair Interface Box: 4822 727 21631.
• AC Adapter: T405-ND.
2
C/UART level.
C/UART bus of the television.
2
C/UART commands to
TO TO
I 2 C SERVICE
CONNECTOR
I 2 C
PC VCR Power
9V DC
E_06532_021.eps
180804
L03.1U AA
• ComPair Quick Start Guide: ST4190.
• ComPair interface extension cable: 3139 131 03791.
• ComPair UART interface cable: 3122 785 90630.
Note: If you encounter any problems, contact your local
support desk.
5.5

The Blinking LED Procedure

Via this procedure, you can make the contents of the error
buffer visible via the front LED. This is especially useful when
there is no picture.
When the SDAM is entered, the LED will blink the contents of
the error-buffer.
• n short blinks (n = 1 - 14),
• When all the error-codes are displayed, the sequence
finishes with a LED blink of 3 s,
• The sequence starts again.
.
Example of error buffer: 12 9 6 0 0
After entering SDAM:
• 12 short blinks followed by a pause of 3 s,
• 9 short blinks followed by a pause of 3 s,
• 6 short blinks followed by a pause of 3 s,
• 1 long blink of 3 s to finish the sequence,
• the sequence starts again.
5.6 Protections
If a fault situation is detected an error code will be generated
and if necessary the set will be put in the protection mode.
Blinking of the red LED at a frequency of 3 Hz indicates the
protection mode. In some error cases, the microprocessor
does not put the set in the protection mode. The error codes of
the error buffer can be read via the service menu (SDAM), the
blinking LED procedure or via ComPair.
To get a quick diagnosis the chassis has one service modes
implemented:
• The Service Default Alignment Mode (SDAM). Start-up of
the set in a predefined way and adjustment of the set via a
menu and with the help of test patterns.
5.7

Repair Tips

Below some failure symptoms are given, followed by a repair
tip.
• Set is dead and makes hiccupping sound. "Main
Supply" is available. Hiccupping stops when de-soldering
L5563, meaning that problem is in the "Main Supply" line.
No output voltages at LOT, no horizontal deflection.
Reason: line transistor 7421 is defective.
• Set is dead, and makes no sound. Check power supply
IC 7520. Result: voltage at pins 2, 6, 7, 9 and 11 are about
180 V and pin 14 is 0 V. The reason why the voltage on
these pins is so high is because the output driver (pin 11)
has an open load. That is why MOSFET 7521 is not able to
switch. Reason: feedback resistor 3523 is defective.
Caution: be careful measuring on the gate of 7521;
circuitry is very high ohmic and can easily be damaged!
• Set is in hiccup mode and shuts down after 8 s. Blinking
LED (set in SDM mode) indicates error 5. As it is unlikely
that the "POR" and "+8V protection" happen at the same
time, measure the "+8V". If this voltage is missing, check
transistor 7491 & 7496.
• Set is non-stop in hiccup mode. Set is in over current
mode; check the secondary sensing (opto coupler 7515)
and the "Main Supply" voltage. Signal "STDBY_CON" must
be logic low under normal operation conditions and goes to
high (3.3 V) under standby and fault conditions.
5. EN 11