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EN 16
5.
EM1.1A AA
HFB X-RAY PROTECT
X-RAY PROTECT
EHT-INFO
HFB
I 2 C SLOW BUS
HIP
HOP
PICNIC
TUNER
NVM
MSP
BOCMA DW
IO-EXPANDER DW
TUNER - DW
MULTI-PIP PROC. DW
IO-EXPANDER HD-JACK
V-CHIP
FBX
PICNIC 3V3
PROTECTION
TUNER
TUNER 8V
PROTECTION
Figure 5-2 Protection diagram
There are several types of protections:
2
•
I
C related protections (for example, +5V supply check).
•
HOP related protections (mainly for deflection items).
•
Hardware errors which are not sensed by the Painter (for
example, BRIDGE_PROT)
2
I
C related protections
In normal operation, some registers of the I
will be refreshed every 200ms. During this sequence, the I
2
busses and the I
C ICs will be checked. The I
take place if the SDA and SCL are short-circuited to ground or
2
to each other. An I
C error can also occur if the power supply
of the IC is missing (for example, FBX_PROT: error 1).
HOP related protections
Every 200ms, the status register of the HOP is read by the
2
Painter via I
C. If a protection signal is detected on one of the
inputs of the HOP, the relevant error bit in the HOP register is
set to "high." If the error bit is still "high" after 1s, the Painter will
store the error code in the error buffer (NVM) and, depending
on the relevance of the error bit, the set may or may not go into
protection mode.
•
HFB: Horizontal Flyback. If the horizontal flyback is not
present, then 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.
•
Flash detection. From the EHT info, via D6303 and T7303,
a flash will stop the H-drive and line output stage
immediately. The FLS bit in the status register of the HOP
is set to "high." As the duration of a flash is very short, the
FLS bit will be reset to "low" again after the flash refresh,
and the set will be started again via a slow start.
Hardware related protections
Due to the architecture (with "hot" deflection) there are two
protections that are "unknown" to the microprocessor, namely
the 'BRIDGE_PROT' (coming from the line stage) and the
'DEFL_PROT' protection (coming from the frame deflection
stage).
If one of these protections is triggered, the set is switched to
"Standby" mode. The Painter will now try to restart the set. If
this does not succeed after 5 times (after 30 - 60 seconds), the
Painter will generate error 2 (this error can have several
Service Modes, Error Codes, and Fault Finding
BCL
XPR (43)
HOP
FLASH DETECT
FLS (5)
NHF (13)
I 2 C
+5V2
PAINTER
I 2 C
I 2 C
CL 16532043_013.eps
190601
2
C controlled ICs
2
2
C protection will
causes, such as repeating flashes, BRIDGE_PROT/Non VFB
leading to DEFL_PROT, or a serious AC power dip). The red
LED will start blinking.
5.8
General tips and repair tips
5.8.1
General
Notice that a very large part of the set (Large Signal Panel) is
"hot," meaning the primary part of the Standby supply, the
whole Main supply (except for the secondary Audio supply),
and the complete deflection circuit are "hot."
Note: The deflection-coil is hot.
This set is not equipped with an IR transmitting LED. Instead,
a Service (ComPair) connector is implemented at the rear of
the set, which is directly accessible (it is not necessary to
remove the back cover to access the connector).
In addition to this, there is a blinking LED procedure to show the
contents of the error buffer.
The relay you hear during switching the set "on" (via the power
switch) is from the degaussing circuitry. So it is not used for
switching the supply as in the MG chassis.
When there is a menu on the screen, it is not possible to enter
a service mode. Be sure there is no menu on the screen when
attempting to enter a service mode.
5.8.2
Main Power Supply
The simplest way to repair the main supply is to check (and
replace, if necessary) the gray marked components on the
Main Supply.
Do not try to perform measurements on the side of the SSB
C
connected to the "hot" heatsink. This is dangerous. Most
relevant service test points are connected to the Tuner side
and are pointed out by service printing. Where the circuitry was
too crowded to place this service printing, it has been explained
on the Test Point Overviews in this manual. It is also possible
to use the SSB extension panel (part number: 9965 000
05769), so that all test points are easily accessible.
5.8.3
Standby Power Supply
The simplest way to repair the standby supply is to check (and
replace, if necessary) the gray marked components on the
Standby Supply.
5.8.4
Horizontal Deflection
The simplest way to repair the horizontal deflection is to check
(and replace, if necessary) the gray marked components on the
Horizontal Line Deflection circuitry.
5.8.5
Vertical Deflection
Caution: When you suspect the Vertical Deflection circuitry,
please be careful. Since there is a DC voltage on the vertical
deflection, the beam current can damage the CRT neck,
leading to a defective CRT.
The best thing to do is:
1. Interrupt pin 2 of connector 1424 on the CRT panel
(diagram F), in order to remove the 'filament' voltage from
the tube (there is no beam current, so there is no chance of
destroying the CRT).
2. Measure the functionality of the Frame stage with a
multimeter or with an oscilloscope.
3. After you have found the cause, exchange the defective
component (for example, TDA8177), and resolder the
interrupted pin 2.
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