Philips 8000 Series Service Manual page 23

Service Modes, Error Codes, and Fault Finding
Constraints taken into account:
- Display may only be started when valid LVDS output clock can be delivered by the AVC.
- To have a reliable operation of the EEFL backlight, the backlight should be driven with a maximum PWM duty
cycle during the first seconds. Only after this first one or two seconds, the PWM may be set to the required output
level (Note that the PWM output should be present before the backlight is switched on). To minimize the artefacts,
the picture should only be unblanked after these first seconds.
The assumption here is that a fast toggle (<2s) can
only happen during ON->SEMI ->ON. In these states,
the AVC is still active and can provide the 2s delay. A
transition ON->SEMI->STBY->SEMI->ON cannot be
made in less than 2s, because the standby state will
be maintained for at least 4s.
CPipe already generates a valid output
clock in the semi-standby state: display
startup can start immediately when leaving
the semi-standby state.
The exact timings to
switch on the
display (LVDS
delay, lamp delay)
are defined in the
display file.
Start POK line
detection algorithm
A LED set does not normally need a
preheat time. The preheat remains present
but is set to zero in the display file.
The higher level requirement is that audio and video
should be demuted without transient effects and that
the audio should be demuted maximum 1s before or
at the same time as the unblanking of the video.
Figure 5-6 "Semi Stand-by" to "Active" flowchart (EEFL or LED backlight 50/100 Hz only)
Semi Standby
Wait until previous on-state is left more than 2
seconds ago. (to prevent LCD display problems)
Display already on?
(splash screen)
No
Switch on the display power by
switching LCD-PWR-ON low
Wait x ms
Switch on LVDS output in the 85500
Delay Lamp-on with the sum of the LVDS delay and
the Lamp delay indicated in the display file
Switch off the dimming backlight feature, set
the BOOST control to nominal and make sure
PWM output is set to maximum allowed PWM
Switch on LCD backlight (Lamp-ON)
Wait until valid and stable audio and video, corresponding to the
the backlight has been switched on for at least the time which is
return
Release audio mute and wait 100ms before any other audio
handling is done (e.g. volume change)
Restore dimming backlight feature, PWM and BOOST output
Switch on the Ambilight functionality according the last status
Yes
back to
div. table
Q551.1E LA
Assert RGB video blanking
and audio mute
Yes
Initialize audio and video
processing IC's and functions
according needed use case.
requested output is delivered by the AVC
AND
indicated in the display file as preheat time.
Switch Audio-Reset low and wait 5ms
and unblank the video.
settings.
Startup screen Option
and Installation setting
Photoscreen ON?
Yes
Display cfg file present
and up to date, according
correct display option?
No
Prepare Start screen Display config
file and copy to Flash
Active
5. EN 23
No
18770_253_100216.eps
100216
2010-Jun-25