2.2 POWER SUPPLY OPERATION
The printer can be powered by either of two power supply boards: the C166 PSB (120 V) or C166 PSE (230
V) power supply. These boards are the same for both the LQ-2170 and FX-2170. Additionally, the PSB and
PSE boards function the same, except for a difference in primary circuitry. The power supply board outputs
the DC current necessary to drive the printer control circuits and drive mechanism. Table 2-5 shows the input
voltages and fuse ratingsfor these boards.
Table 2-5. Power Supply Board
Board Input Voltage Fuse F1 Rating
C166 PSB 103.5 to 132VAC 3.15A / 125 V
C166 PSE 198to 264 VAC T2.0 AH / 250 V
2.2.1 Power Supply Overview
The power supply board has two power outputs for use by the various control circuits and drive mechanisms.
Table 2-6 lists theapplications for the twoDC output supplyvoltages.
Table 2-6 Power Supply Output Voltages andApplications
Output Voltage (DC) Applications
+5 V Main Board Logic Circuit Sensors Control Panel LEDs
+35 V CR Motor PF Motor Printhead Drive
Figure2-22 shows a block diagram ofthe power supply circuitry.
As shown in the figure above, when AC power enters the printer from an external power source, the filter
circuit removes the noise. The AC voltage then undergoes full-wave rectification and is smoothed to produce
direct voltage. The voltage is fed to the gate port for the switching FET (Q1: K2126 or K2130) through
resistors R18 and R31, and then the switching circuit operates. The secondary smoothing circuit produces a
stepped down +35 VDC voltage. The +5 VDC voltage is generated by feeding the +35 VDC voltage through
the +5 VDC power supply circuit, where the +35 VDC is stepped down to a stable +5 VDC from the 35 VDC
line.
Filter Circuit
Full Wave
Rectification
Circuit
Smoothing
Circuit Switching
Circuit
AC input
Smoothing
Circuit
+5V Switching
Regurator
+5V Over current
Protection Circuit
+35V DC
+5V DC
Photo-
Coupler
Photo-
Coupler +35V Line
Over Voltage
Protection Circuit
+35V Line
Over Load
Detector Circuit
+35V Line
Over Current
Protection Circuit
Operation
SW
Primary Circuit Secondary Circuit
CPU
Port 20
+35V Line
Constant Voltage
Control Circuit
+5V Line
Over Voltage
Protection Circuit
+5V Constant Voltage
Control Circuit
Figure 2- 22 Power Supply Circuit BlockDiagram
FX-2170 ServiceManual Operating Principles
Rev.A 2-17