Reset Circuit; Vx Voltage Supply Circuit - Epson LQ-1050 Technical Manual

REV.-A

2.3.1 Reset Circuit

Figure 2-22 shows the reset circuit. After being input to gate array EO5A1OAA (MMU: 10C), the RESET
signal resets the gate array and is then sent out to the other devices.
Hardware reset is performed when:
1. The printer power is turned on or off.
2. A low INIT signal is input from the host computer.
3. A cartridge is installed or removed with the power on.
I
I
>

2.3.1.1 Vx Voltage Supply Circuit

Power voltage Vx is supply to the power-on reset circuit and INIT reset circuit. It is also used to pull
up the output of buzzer driver 6B and the head data control output port of G/A (3A).
Figure 2-23 shows the circuit diagram.
After power is applied, the 35 V line reaches about 27.7 V, and then Q31 and Q32 are turned on so
that current IG flows from the + 5 V line to the Vx line. Therefore, + 5 V is applied to the Vx line. (The
resistance between the emitter and collector of Q32 is assumed to be O ohms.) If the +35 V line drops
below 27.7 V, Q31 and Q32 are turned off so that the Vx line drops to O V. The IC is therefore reset
and the printer stops printing.
M MU
I
Fig. 2-22. Reset Circuit
CN 17
+ 5 r-l
I I
I
Fig.2-23. Vx Power Supply Circuit
{ Ic 2)
COUNTER I
IN 2
R OUT
C6 : : Q31
2-22
C PU (7B )
RESET
On
MONMA
RESET of 555 (7C)
RESET of MCU ( 2A)
RESET of CN2
of
V x
To
External