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LF¢MA
LF¢MB
LF¢MC
LF¢MD
MA-0383-82
Figure 4-8 Line Feed Motor Phase Patterns
4.4.5 Power Supply - The power supply is located on the printed circuit board. The supply generates a
regulated +S Vdc, and unregulated +S Vdc and 27 Vdc. In addition, a de to de converter transforms the
regulated + S V de to + 12 V de and -12 V de. Figure 4-9 shows a block diagram of the power supply. The
diagram includes a wake-up circuit. This circuit controls the initial state of the logic circuits during power
turn on and off.
4.4.5.1
Input Requirements - The ac input operating voltage for each model of the LASO is factory pre-
set. The label on the fuse plate shows the power requirements. The models and their operating voltages are
as follows:
LASO-RA
LASO-RB
LASO-RC
LASO-RD
120 Vac
220 Vac
240 Vac
100 Vac
The operating power frequency range is between 47 and 63 Hz.
The plug-in position of a connector at the input to the power transformer allows changing the operating
voltage of the models. RA and RD models can operate at either 100 or 120 volts. RB and RC models can
operate at either 220 or 240 volts. Refer to Paragraph 6.2.2 for the voltage change procedure.
4.4.5.2 Outputs - The following lists the power supply outputs and their use.
+S Vdc regulated
+S Vdc unregulated
+ 12 V de and - 12 V de
regulated
+ 27 V de unregulated
Logic and control circuits
Wake-Up/reset circuit
RS232C output interface dual
line drivers
Printhead, linefeed motor, and
carriage motor drivers.
4.4.5.3 Functional Description - The ac line voltage entering the supply is fused, filtered, and passes
through a voltage selection connector before going to the power transformer. The secondary of the trans-
former feeds two bridge-type full-wave rectifier circuits. A capacitor-resistor network smooths the 27 volt
output at one of the rectifier bridges. The other rectifier bridge supplies unregulated S volts directly from
the bridge and a regulated S volts after regulation by a series-feedback circuit.
The Wake-Up circuit senses when the 5 volts is turned on and resets the logic circuits. In addition, it con-
trols the printhead and line feed motor drive circuits to prevent transients during power turn on and off.
4-12
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Troubleshooting
