Service Modes, Error Codes and Fault Finding
EN 29EM5A P/M 5.
6. When you switch “off” the set, this is done in a controlled
way via the POR signal [3].
Note: Standby is not directly achieved via the Standby line of
the microprocessor, but indirectly via the HOP circuitry.
5.8.3 ComPair
This chassis does not have an IR transmitting LED (as in MG-
sets). Therefore, a “Service” (ComPair) connector is
implemented at the rear side of the set, which is directly
accessible (as in A10-, EM2E- and EM3E-sets). In addition to
this, there is also a blinking LED procedure to show the
contents of the error buffer.
When you use ComPair, you have the possibility to activate a
“stepwise start-up” mode. With this mode, you can initiate the
start-up sequence step by step. This also means that in certain
steps, some protections are not activated. This is sometimes
very convenient during repair (see also paragraph “Stepwise
Start-up / Shut-down”).
5.8.4 Protections
There are “service pads” implemented on the SSB (items 9005
and 9006, outside the shielding), to force the set in SAM or
SDM (see also figure: “SSB removal (part 3)” in chapter
“Mechanical Instructions “). This will overrule the processor-
controlled protections, but not the hardware protections. This
means, that the A/D-input protections (5 and 8 V) and the I
2
C
“not-acknowledging” info of the feature box (FBX) and of the
Tuner are overruled.
Caution: When doing this, the service technician must know
what he is doing, as it could lead to damaging the set.
The ‘ARC’- and/or ‘BRIDGECOIL’ protection are hardly ever
triggered, however:
When you suspect the ‘ARC’ protection, look for bad solder
joints and smell. By interrupting resistor 3497, this protection is
disabled (special attention needed!).
When you suspect the ‘BRIDGECOIL’ protection, which can
also be due to, a too wide picture amplitude, shorten G and S
of the E/W MOSFET 7480. This will disable the protection. You
will now have minimal horizontal amplitude. Re-align the
horizontal amplitude in the SAM menu and remove the G/S
short of TS7480.
5.8.5 Main Supply
The simplest way to repair the main supply is to check and
replace if necessary the gray marked components on the Main
Supply.
More detailed way:
1. Replace FET 7504 and zener 6505.
2. Remove the SSB panel.
3. Short B and E of TS7529, in order to put the Main Supply
in “on”-mode (TS7529 is blocking then).
Caution: To prevent that R3403 and TS7443 will be
damaged, first disable the HW-protection of the
deflection circuit. Therefore short circuit C2642 on the
LSP (diagram A4).
4. Attach a load (60 W light bulb) to V
BAT
capacitor C2515 (the
supply can not work without a minimum load).
5. Use a variac, and slowly increase the V
MAINS
. Measure
over sensing resistors R3514//15 if a nice sawtooth voltage
becomes available.
6. Also measure the V
BAT
. This may never exceed +141 V. If
it does, there is something wrong in the feedback circuitry
(e.g. regulator 7506).
Note: Be careful when measuring on the gate of FET TS7504.
This circuitry is very high ohmic and can easily be damaged
(first connect ground to measuring equipment, than measure
the gate).
5.8.6 Standby Supply
The simplest way to repair the stand by supply is to check the
gray marked components on Stand By Supply.
5.8.7 Line Deflection
The simplest way to repair the line deflection is to check the
gray marked components on Line Deflection.
5.8.8 Frame Deflection
Caution: When the Frame Deflection circuitry is suspected, one
must be careful. Because there is a DC-voltage on the frame
deflection, the beam current could damage the CRT neck,
leading to a defective CRT.
Best thing to do is:
Interrupt the resistors 3403 and 3404 on the CRT panel
(diagram F1), in order to remove the “filament” voltage from the
tube (no beam current, so no chance of destroying the CRT).
Interrupt resistor 3403 on the LSP (diagram A4) to disable the
‘SUP-ENABLE’ line.
Measure with a multi-meter, or better with a oscilloscope, the
functionality of the Frame stage.
After you have found the cause, exchange the defective
component (e.g. TDA8177), and re-solder the interrupted
resistors.
Table 5-4 Repair Tips
Phenomenon Possible Cause Repair tip
No picture, no LED. Standby Supply defective. Measure circuitry (see diagram A2). Start at test-point A19.
When the Mains switch is "on", this voltage must always be available
No picture, no LED. Bad connection of SSB in
SIMM-connector.
In case of a bad connection, it can happen that there is no picture, and
that the Standby LED is not controllable. Re-place the SSB.
No picture, red LED blinking
at 3 Hz.
Set is in protection due to var-
ious causes. For error codes
see error-code list.
You have no picture, so:
-Read the error buffer via ComPair (error buffer is accessible when set is
in protection, ComPair-file will guide you to this)-
-Read the blinking LED information via standard remote command
<mute>06250X<ok>
-Or you read the error code sequence via standard remote command
<mute>062500<ok>.
When you have found the error, check the circuitry related to the supply
voltage and I
2
C-communication or the circuitry that triggers the protection.
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