Star Micronics MP111MP-24G-A User Manual

– 19 –

Notes: Adjust motor speed with VR

adjustment and T1 signal to

1660 Hz 

±

 30 Hz.

Fig. 3-15 Motor drive circuit (example)

R1

10 K

Ω

TR1

2SA950

R2

3.3 K

Ω

TR2

2SC1740

R3

6.8 K

Ω

1/6 W

TR3

2SA1175

R4

2.2 K

Ω

TR4

2SD882

R5

1.2 K

Ω

TR5

2SB1359

R6

10 K

Ω

TR6

2SD1637

R7

20 K

Ω

IC1

SN74LS05

C1

0.47 

µ

F (Film)

IC2

M51971L (MITSUBISHI)

C2

0.033 

µ

F (Film)

VR

6.8 K

Ω

C3

0.022 

µ

F (Film)

The motor control circuit with a Frequency Governor circuit maintains the printing speed at the settings.  It is

mainly constructed  of a Speed Control IC (IC2) and a Power Transistor TR6 shown in Fig. 3-15.  It measures

the number of rotations of the Carriage Motor from the Timing Signal 1.  This signal is then compared to the

standard signal to control the speed by controlling the voltage energizing the Carriage Motor.

The FG circuit maintains a stable output regardless of the environment where it is being used.

It maintains stability even at high speeds.

It protects the head because the speed is stable.