Professional 4400 Chassis service procedure
Power module
Use PP1 to select 154V ± 0.5V for 4:3 tubes and 151V ± 0.5V for 16:9 tubes at the CP28
terminals.
Activating service mode
1.
Switch on the appliance while holding down the
MENU key at the cabinet controls
until the red LED lights up.
2.
Release the MENU button at the cabinet and press the
standby
button on the remote
control; the appliance will default to programme 1 or to AV1 if pin 8 of SCART 1 is
connected to a voltage of +12 V. It is therefore important to make certain that the test
signal needed to make the adjustments is available either on programme 1 or on the
SCART 1 input, as selection of the sources is not possible thereafter in service mode.
3.
The functions that can be adjusted (listed below) are selected using the
P+
and
P-
buttons of the remote control and the adjustments then made with the
Volume ±
buttons. It
is advisable to make a note of initial values before making any changes so that these can
be restored if necessary.
In the event of replacing the NVM memory or the microprocessor, it is essential to make
all the adjustments accessible in service mode, since the replacement memory is
supplied without any prior programming and a new microprocessor requires a new
initialization.
Option bytes (Opx)
The correct values to set for each appliance are given on the label at the back cover alongside the
letters
Op1
,
Op2
,
Op3
.
Initialization (INIT CTV 831 x.x)
The initialization procedure, which also indicates the software version for the microprocessor, is
enabled with the
button and
must be carried out whenever the NVM memory or
the microprocessor is replaced. Bear in mind that initialization has the effect of erasing
all data from the memory except for the bytes option
.
Control bytes (Cox)
These are control registers that
must be set
as follows:
Co2
96
Co3
27
Co4
00
Screen grid voltage (Vg2 Test)
Having selected the function, press the button: a luminous horizontal line appears in the
middle of the screen. Adjust potentiometer G2 on the EHT transformer so that the line is just
visible (in a dimly lit room). Then press Volume- and
wait for a few seconds
until service mode is
restored.
IF video setting (Ifxx AFCxx)
This adjustment requires special equipment and will be needed only for the ICC2 N1 version, which
is also recognizable by the presence of the LC7 coil. If the coil is present, adjust IF and IFP to the
values given on the label affixed to the left side of main PCB so that a suitable approximation is
achieved.
If the coil is not present, adjust as follows:
IF
50
