Fault finding and repair tips
GB 25
EM1A
5.
Phenomenon
Possible Cause
Repair tip
No picture, no LED.
Standby Supply defective.
Measure circuitry (see diagram A2). Start at test-point P16.
Regardless the mode of the set, this voltage should always be available.
No picture, red LED
(high intensity).
Despite expectation,
the set should be ON
(this looks like
Standby). After some
time LED will start
blinking.
There are 2 protections (which
are not ’seen’ by the processor)
that force the set in protection
(after 5 restart attempts):
BRIDGE_PROT or MAINS DIP
error.
If protection is activated due to an absence of the Frame deflection, this
can be measured on test-point F10 (diagr. A4). Error 33 will be generated.
The BRIDGE_PROT could be triggered by an E/W failure.
An MAINS_DIP error (error 7) will be generated in both cases after 5
restart attempts, and will be visible via the blinking LED procedure.
ComPair is very useful here.
Set going into
protection after 5
restarts (error 7),
taking about 30 - 60 s.
180 V missing on CRT-panel
(diagr. F). Most probably R3341
is interrupted, or RGB-amplifier
IC7307 is defective.
Measure 180 V behind R3341 (diagr. F) while operating, or measure
resistance of R3341 while set is of.
No picture, red LED
blinking (3 Hz)
Set is in protection due to
various causes. For error codes
see error code list.
You have no picture, so:
Read out the error buffer via ComPair.
Read out blinking LED information via ’DIAGNOSE X’ with DST.
When error is known, check circuitry related to supply voltage and I
2
C -
communication.
No picture, red LED
blinking (code 6, 6, 6)
No communication on I
2
C1-bus
(’devices’ bus) to processor. Set
is in protection-mode
Measure, dependent of the error, on the I
2
C-bus which device is loading
the bus. This protection can be overruled via SDM-entry (via short-
circuiting FRONT_DETECT to GND on Side I/O).
No picture, red LED
blinking (code 10, 10,
10)
No communication on I
2
C3-bus
(’NVM’ bus) to processor. Set is
in protection-mode
No contact of processor with the NVM. A lot of settings will therefore be
wrong.
No picture, no sound,
set is making audible
squeaking sound
Supply could be in hiccup-mode
which can be heard via supply-
transformer squeaking
This could be caused by:
Short-circuited V
BAT
(caused by short circuited line transistor 7421) or
Short-circuited sound-winding (amplifier is short-circuiting 28 V) or
Short-circuited D6514 (due to a too high V
BAT
).
Delete excessive load to see where failure is caused by or check feed
back circuit. See repair-tip main power supply (supply needs a minimal
load).
No picture, no sound,
LED works fine
Supply does not work correctly
If e.g. V
BAT
is only about 90 V, regulator-IC 7506 could be damaged.
No RC5-reception.
Red LED does not
echo RC-commands.
Processor-circuitry or RC-
receiver is wrong.
In case set reacts on local keyboard operation, error must be found in the
IR-receiver circuitry (diagram J).
Relay-activation
(degaussing) not
audible when switch
set on from off .
Processor not working correctly.
Check RESET-circuitry on diagram B5. When switching on the set all I/o-
pins of processor should become high for a moment, so also the degauss-
input signal.
No sound, but picture.
Measure P7 on diagram A1.
Possible sound-amplifier is
defect (but not short-circuited),
or sound-enable line is high
(see diagram A5).
Further the audio-signal path
must be measured (HIP, MSP,
switch-IC s, amplifier).
Measure and repair. With ComPair there is a beep-test that can determine
where the signal stops (use loudspeakers, headphone).
No sound at
headphone output.
Discrete amplifiers or supply to
it could be damaged.
Measure A12, A13, A14, A15 and supply-line on diagram A6.
Picture is rotated.
Rotation-circuitry or supply to it
could be damaged (if present).
Measure test-points F3, R1, R2 on diagram A4.
No picture.
Check functionality and cabling
Tuner to SSB.
Notice cable 1946.
Picture looks like
cushion, further OK
Or NVM-content is overwritten
or E/W-MOSFET is short-
circuited
First check in Service Alignment Mode, whether geometry can be
restored. If not check test point L4 and diagram A3, or measure with an
ohmmeter whether TS7480 is defective.
Very white picture,
with flyback lines
visible
180 V is missing on CRT-panel
Probably R3468 on LSP (diagram A3) is interrupted, or bad connection
plug 0324 to 0224 (CRT-panel).
Un-sharp picture
Focus could be misaligned or
SCAVEM-circuitry does not
work correctly
Align focus-potmeter of Line Transformer; check SCAVEM-circuitry on
CRT-panel [F].
Un-synced picture
Sync is derived in HIP-IC from
X-tals 1309 and/or 1310
Maybe an X-tal is making bad contact.
Picture distorted.
Check video-path, service
default mode.
Investigate whether there exists an error code in the error buffer.
In case there is an error code, check I
2
C-bus and/or supply-lines (see
overview supply-lines).
Measure and check signal path Tuner, HIP, PICNIC, HOP, RGB-amplifier.
In case it is a geometry-issue, check Frame-circuitry, alignments or
possible corrupted NVM (7012)
No menu, OSD.
Probably processor is defective.
Measure test points C7, C8, C9, C10 on diagram B7.
CL 06532111_057.EPS
121000
