
III
- 15
3.3 POWER SUPPLY PCB
3.3.1 +12V Power Supply Circuit
Fig. 3.3-1 shows the +12V power supply circuit. Acting as a DC stepping-up converter,
this circuit steps up the AC adapter output to +12 VDC power supplies, VH and VM. The
VH is fed to the thermal head and the VM is fed to the tape feed motor and cutter motor.
A closed loop comprising Q1, Q2, R2, R4, and C4 forms a self-running oscillator. Zener
diode ZD1 and Q4 regulate the output voltage "A" 12V.
The CPU turns the HPOW signal High to apply power to this circuit only when driving the
mechanisms, thereby saving power. When no power is required for those mechanisms,
the CPU cuts off Q5 (FET) by keeping the HPOW Low to protect them from unexpected
powering.
Resistor R13 limits the current flowing into the motors.
Fig. 3.3-1 +12V Power Supply Circuit
Содержание PT-2500PC
Страница 1: ...SERVICE MANUAL MODEL PT 2500PC ...
Страница 2: ...SERVICE MANUAL MODEL PT 2500PC ...
Страница 5: ...CHAPTER I SPECIFICATIONS ...
Страница 11: ...CHAPTER II MECHANISMS ...
Страница 49: ...CHAPTER III ELECTRONICS ...
Страница 68: ...CHAPTER IV TROUBLESHOOTING ...
Страница 72: ...IV 3 3 The ON OFF lamp LEDs will not come on 4 No printing is performed ...
Страница 73: ...IV 4 5 Interface malfunctions 6 No tape cutting ...
Страница 74: ...IV 5 7 Tape feeding error ...
Страница 75: ...IV 6 ...
Страница 76: ...APPENDICES Circuit Diagrams A Main PCB B Power Supply PCB ...
Страница 79: ...Nov 98 5V2086BE0 Printed in Japan ...