Input Filter Circuit; Rectifier, Smoothing, And Surge-Suppression Circuit - Epson LQ-1050 Technical Manual

REV.-A

2.2.2 Input Filter Circuit

Figure 2-9 shows Input filter circuit. The filter circuit attenuates external noise and inhibits noise
generated in the printer from going out over the AC line. The coils-and capacitors employed in this filter
are able to handle fluctuations of the AC input line. Frame ground (F. G.) is connected between
C5, which handle leakage current from the frame to the AC line.

2.2.3 Rectifier, Smoothing, and Surge-Suppression Circuit

As
shown in Figure 2-10, the AC input voltage filtered by the input
bridge DB 1, and is smoothed by C6. The voltage across C6 is normally O V before the power is turned
on. Therefore, the initial input current is shorted by C6 via DB 1 and a large charging current (called
a surge current) flows when the power is turned on. Figure
The largest surge current flows if the power supply is turned on at the peak of the input voltage.
INPUT F
ILTER
CIRCUIT
Fig. 2-9. Input Filter Circuit
Fig. 2-10. Rectifier-Smoothing-Surge Suppression Circuit
shows the surge current.
R I
1
TY
I
2-12
is full-wave rectified by diode
MAIN SWITCHING
CIRCUIT
and
TO