Philips BJ2.4U Service Manual page 19

Repair Tips
In case only one or no lamp unit at all works, probably the
+12Vb (12 - 13 V) is not available or the fuse is broken. Check
for broken MOSFETS or check if they are switched off properly
by the transistors connected to the PWM outputs of the
microprocessor.
In case the Ambi Light switches off after two seconds, serial
arcing or parallel arcing protection is active. Serial arcing
protection can be excluded by disconnecting the opto-coupler;
check for bad solder joints on transformer or lamp units.
Parallel arcing protection can be disabled by grounding pin 8 of
the microprocessor. Usually the switching frequency (normally
63 kHz) will then be too high. Possible causes are one
MOSFET of the converter has no gate drive or is broken, or
there is a short-circuit of the output of the transformer.
5.3 Stepwise Start-up
The stepwise start-up method, as known from FTL/FTP sets is
not valid any more. The situation for this chassis is as follows:
Service Modes, Error Codes, and Fault Finding
Mains
"off"
- WakeUp requested
- Acquisition needed
Stand-by
(Off St-by)
- No data Acquisition required
and no POD present
- Tact SW pushed
- WakeUp requested
- Acquisition needed
- POD Card remove d
- Tact SW pushed
POD
Stand-by
On
*
TM
Only applicable for sets with CableCARD slot (POD)
Figure 5-5 Transition diagram
when the TV is in a protection state detected via the Stand-by
Processor (and thus blinking an error) and SDM is activated via
shortcutting the pins on the SSB, the TV starts up until it
reaches the situation just before protection. So, this is a kind of
automatic stepwise start-up. In combination with the start-up
diagrams below, you can see which supplies are present at a
certain moment.
Important to know here is, that if e.g. the 3V3 detection fails
(and thus error 11 is blinking) and the TV is restarted via SDM,
the Stand-by Processor will enable the 3V3, but will not go to
protection now. The TV will stay in this situation until it is reset
(Mains/AC Power supply interrupted).
The abbreviations "SP" and "MP" in the figures stand for:
• SP: protection or error detected by the Stand-by
Processor.
• MP: protection or error detected by the VIPER Main
Processor.
Off
Mains
"on"
WakeUp
requested
Semi
Stand-by
- St-by requested
- Tact SW pushed
No data Acquisition
WakeUp
required and
requested
POD present
GoToProtection
*
GoToProtec tion
Protection
BJ2.4U/BJ2.5U PA
Active
GoToProtection
F_15400_095.eps
020206
5. EN 19