Philips EM5E AA Service Manual page 32

EN 32 5.
• The Service Alignment Mode (SAM). In this mode, items
of the set can be adjusted via a menu and with the help of
test patterns.
You can enter both SDM and SAM modes via the 'service pads'
on the SSB, via an RC-transmitter (DST or standard RC), or via
ComPair. It is not possible to enter the SAM in 'standby'; the TV
has to be in 'normal operation' mode.
The EM5E 'Protection Diagram' shows the structure of the
protection system. See diagram below.
EHT-info
HFB
I 2 C PROTECTIONS
HIP
HOP
PICNIC
TUNER
NVM
DNR
MSP
TOPIC
FBX
PICNIC 3V3
PROTECTION
TUNER
*
3D COMB
Figure 5-2 Protection diagram
There are several types of protections:
2
• I C related protections.
• OTC related protections (via polling on I/O pins or via
algorithms).
• HOP related protections (mainly for deflection items).
• Hardware errors that are not sensed by the OTC (e.g.
vertical flyback protection, bridge coil protection, E/W
protection, arcing protection).
All protections are explained below.
2
5.7.2 I C Related Protections
In normal operation, some registers of the I
are refreshed every 200 ms. During this sequence, the I
2
busses and the I C ICs are checked.
2
An I C protection will take place if the SDA and SCL lines are
short-circuited to ground, or to each other. An I
occur, if the power supply of the IC is missing (e.g. FBX_PROT
(error 16)).
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 P 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 HOP, HIP, MSP, PICNIC, NVM, and Tuner are
EM5E Service Modes, Error Codes and Fault Finding
7301
XPR (43)
LEVEL
HOP
DETECT
FLASH
FLS (5)
DETECT
HFB-XRAY-PROT
I 2 C
7001
+8V_CON
+8V SENSE (105)
+5V_CON
+5V SENSE (106)
OTC
I 2 C
I 2 C
CL 26532041_081.eps
(* )
NTSC SETS ONLY
2
C controlled ICs
2
C error will also
initialised again, to ensure the normal picture and sound
conditions of the set.
8 V and 5 V protection: The µP 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.
5.7.4 HOP Related Protections
Every 200 ms, the status register of the HOP is read by the
OTC (via the I
of the inputs of the HOP, the relevant error bit in the HOP
register is set to 'high'. If this error bit is still 'high' after 1 s, the
OTC will store the error code in the error buffer of the NVM and,
depending on the relevancy of the error bit, the set will either
go into the protection mode or not.
The following protections are implemented:
• HFB (Horizontal Flyback): If the horizontal flyback is not
present, this is detected via the HOP (HFB_X-
RAY_PROT). One status bit is set to 'high'. The error code
is stored in the error buffer and the set will go into the
protection mode.
• XPR (X-ray protection): If the HFB pulses are too low
(level detection), the HOP will detect this via the XPR-bit.
The error will be logged in the error buffer and the set will
go into protection mode.
Note: Both errors will be logged as HFB-failure.
5.7.5 Hardware Related Protections
Due to the architecture ('hot' deflection), some protections
cannot be sensed by the microprocessor. Three of these
protections will lead to a protection on set level (Standby mode
and blinking LED), while another will only lead to a circuit
protection.
190402
TV-set Protection
The following fault conditions will lead to a 'complete' set
protection:
• BRIDGECOIL protection: This is sensed via the 'EW'
signal going to the base of TS7652 (via R3495 and D6499).
In a normal situation, the voltage on C2498 (diagram A4) is
high and TS7652 is conducting. When bridge coil 5422
(diagram A3) is short circuited, the voltage on C2498
changes to low, which will block TS7652. In this case, also
TS7641 will block and the voltage on 2642 will rise until
TS7443 is forced in conduction. The 'SUP-ENABLE' signal
(in normal operating condition -20 V) is shorted now to
ground level, which will force the Main Power Supply to
Standby mode.
• ARC protection: If there are 'open' connections (e.g. bad
solder joints) in the high-energy deflection circuitry, this can
lead to damaging effects (read: fire). For that reason, the E/
W current is sensed (via 3479//3480). If this current
2
C
becomes too high, the 'thyristor' circuit (TS7653 and
TS7654) is triggered. TS7442 is switched 'on' and TS7443
is forced into conduction. . The 'SUP-ENABLE' signal is
shorted now to ground level, which will force the Main
Power Supply to Standby mode.
• NON_VFB (No vertical Flyback) protection: If the frame
stage generates no pulses, TS7641 will block. TS7443 is
now switched 'on', which will lead to Standby mode. So, in
normal operation condition, TS7641 and TS7652 are
conducting, while TS7443 is blocked.
Circuit Protection
The following fault condition will lead to a 'partly' set protection:
• PROT1 (DC) protection: When a DC-voltage (positive or
negative) is sensed on one of the loudspeaker outputs, the
protection circuit (TS7704, 7705, 7706 and 7707 in
2
C bus). If a protection signal is detected on one