138 EasyCoder PX4i and PX6i Service Manual
Chapter 14 — Driver Board
14.1 Description
While the power supply unit (PSU) transforms the AC input voltage to
24 VDC, the driver board converts the 24 VDC to various voltages and
distributes them to CPU board, stepper motors, cutter, and printhead.
The driver board is connected to the PSU via two cables (see Chapter
13). One cable, connected to P2, supplies the driver board with 24 VDC
and the other one, connected to P3, contains temperature and power fail
signals.
The driver board converts the 24 VDC to various voltages required by the
printer and distributes them as follows:
P1 24 VDC to CPU board and control signals between driver board and
CPU board
P5 24 VDC to thermal printhead
P7 0-12 VDC to fan (presently not used)
P10 33 VDC to platen roller/ribbon rewind stepper motor
P11 33 VDC to liner/batch rewind unit stepper motor
P12 24 VDC to cutter interface
At start-up, the PIC processor on the driver board checks that the 24 VDC
to the printhead and 33 VDC to the stepper motors are within allowed
limits. If any extreme values are found, an error condition occurs.
14.2 Replacement
• Take precautions to avoid any electrostatic discharges.
• Switch off the printer and disconnect the power cord
• Remove the left-hand cover as described in Chapter 3.3.
• Disconnect all cables to the driver board.
• From the media compartment, remove the two #T20 Torx screws that
hold the driver board assembly.
• The driver board and its plate come as an assembled spare part. Do not
dismantle any further. Do not attempt to repair a faulty driver board,
but replace it with a new one, unless you know for sure that you have
made the fuse blow by causing a short-circuit (see Chapter 17.6).
• Assemble in reverse order.
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