Epson C117001-N - DFX 5000+ B/W Dot-matrix Printer, Руководство по обслуживанию

Страница: 55 / 186

Operating Principles
Service Manual
The +35
regulator circuit includes the following:
Input voltage line over-current protection (primary side)
IC101 and detect the input voltage of the primary circuit. When the input voltage is normal,
the current does not flow into the shunt regulator. When the over-current flows to the input
voltage line, the shunt regulator is turned on,
and are turned on, and
is turned off.
+35
line over-current protection circuit
If the +35 line drops to +13 the sensor circuit consisting of and
turns on is turned on, PC2 is turned on, and then the input voltage is cut. At this
time, the delay timing creation circuit (CR circuit) consisting of
C157 and makes the delay
timing.
When the printer is turned on, the delay timing creation circuit cannot start this protection
circuit; if it is operated during the driver check, the power supply board cannot be
turned on. The CR circuit has approximately a one-second delay timing.
+35
powerdown detection circuit
When the +35 line drops (such as, when the printer has exceeded its duty cycle and the
temperature is too high), the voltage of PC101 approaches O If the voltage drops to
1.3
outputs a HIGH signal to the base of transistor monitors the
two +35 line creation circuits.
creation circuit
When the printer is turned on, the power supply board assembly c13 to check
the drivers on the MAIN board assembly. After 140 ms, the MAIN board
assembly sends the (driver error) or the VPC (+35 permission) signal to the C117
power supply board assembly. If the drivers are normal, the VPC signal is HIGH,
is turned on, and Q181 is turned off. Therefore, six diodes create the +35 During the
motor driver check, the VPC signal is LOW. When this signal is LOW, Q182 stays off, the base of
stays HIGH, and then two Zener diodes and 13
2.2.4 Half-wave Rectifier Smoothing Circuit
The power from the half-wave rectifier smoothing circuit is mainly supplied to the RS-232C
interface on the standard or optional board and uses the
fire trigger. Both the
and -12 lines have a half-wave rectifier circuit. This smoothing circuit consists of capacitors
and Two Zener diodes stabilize the line.
o
Circuit
surge-cut
Rectifier Smoothing
Circuit Circuit
C+
o
I
I
❑
Main switching
Smoothing Circuit
=
Smoothing Circuit
Circuit (1)
o
o
Creation
Over Current
Protection
+12
-12
Figure 2-17. Half-wave Rectifier Circuit
2-16
Rev.