The Blinking Led Procedure - Philips PB52.1HU LA Service Manual

5.7

The Blinking LED Procedure

5.7.1 Introduction
The blinking LED procedure can be split up into two situations:
• In case of a protection. In this case the error is
automatically blinked. This will be only one error, namely
the one that is causing the protection. Therefore, you do
not have to do anything special, just read out the blinks. A
long blink indicates the decimal digit, a short blink indicates
the units.
• In the "on" state. Via this procedure, you can make the
contents of the error buffer visible via the front LED. This is
especially useful for fault finding, when there is no picture.
When the blinking LED procedure is activated in the "on" state,
the front LED will show (blink) the contents of the error-buffer.
Error-codes > 10 are shown as follows:
1. "n" long blinks (where "n" = 1 - 9) indicating decimal digit,
2. A pause of 1.5 s,
3. "n" short blinks (where "n"= 1 - 9),
4. A pause of approximately 3 s,
5. When all the error-codes are displayed, the sequence
finishes with a LED blink of 3 s,
6. The sequence starts again.
Example: Error 12 8 6 0 0.
After activation of the SDM, the front LED will show:
1. 1 long blink of 750 ms (which is an indication of the decimal
digit) followed by a pause of 1.5 s,
2. 2 short blinks of 250 ms followed by a pause of 3 s,
3. 8 short blinks followed by a pause of 3 s,
4. 6 short blinks followed by a pause of 3 s,
5. 1 long blink of 3 s to finish the sequence,
6. The sequence starts again.
5.7.2 How to Activate
Use one of the following methods:
• Activate the SDM or CSM. The blinking front LED will
show the entire contents of the error buffer (this works in
"normal operation" mode).
• Transmit the commands "MUTE" - "062500" - "OK"
with a normal RC. The complete error buffer is shown.
Take notice that it takes some seconds before the blinking
LED starts.
• Transmit the commands "MUTE" - "06250x" - "OK"
with a normal RC (where "x" is a number between 1 and
5). When x= 1 the last detected error is shown, x= 2 the
second last error, etc.... Take notice that it takes some
seconds before the blinking LED starts.
5.8 Protections
5.8.1 Software Protections
Most of the protections and errors use either the stand-by
microprocessor or the MIPS controller as detection device.
Since in these cases, checking of observers, polling of ADCs,
and filtering of input values are all heavily software based,
these protections are referred to as software protections.
There are several types of software related protections, solving
a variety of fault conditions:
• Protections related to supplies: check of the 12V, +5V,
+1V2, +1V4, 2V5 and +3V3.
• Protections related to breakdown of the safety check
mechanism. E.g. since the protection detections are done
by means of software, failing of the software will have to
initiate a protection mode since safety cannot be
guaranteed any more.
Service Modes, Error Codes, and Fault Finding PB52.1HU LA
Remark on the Supply Errors
The detection of a supply dip or supply loss during the normal
playing of the set does not lead to a protection, but to a cold
reboot of the set. If the supply is still missing after the reboot,
the TV will go to protection.
Protections during Start-up
During TV start-up, some voltages and IC observers are
actively monitored to be able to optimize the start-up speed,
and to assure good operation of all components. If these
monitors do not respond in a defined way, this indicates a
malfunction of the system and leads to a protection. As the
observers are only used during start-up, they are described in
the start-up flow in detail (see paragraph "Stepwise Start-up").
5.8.2 Hardware Protections
The only real hardware protection in this chassis is (in case of
an audio problem) the audio protection circuit that will switch
"off" immediately the supply of the SSB. The supply will buzz
during the protection and +12VS drops to approximately 5V5
and +5V Stand-by to approximately to 1V9. Other indication of
the audio protection is that the red LED lights up with an
intensity of 50%.
Repair Tips
• It is also possible that you have an audio DC protection
because of an interruption in one or both speakers (the DC
voltage that is still on the circuit cannot disappear through
the speakers). Caution: (dis)connecting the speaker wires
during the ON state of the TV at high volume can damage
the audio amplifier.
5. EN 31