Dc Jack-Related Circuit - Brother PT-2500PC Service Manual

3.3.2 +5V Power Supply Circuit
Fig. 3.3-2 shows the +5V power supply circuit. A 3-terminal regulator (KIA7805P, Q6)
stabilizes the Vcc (approx. 5V). During non-printing, the regulator is supplied with the
VAD fed through the AC line adapter output. During printing, it is supplied with "A"
(+12V) fed from the +12V source; this is to supply the stabilized power to the logic
circuitry even when the AC line adapter output drops abnormally.
3.3.3

DC Jack-related Circuit

Fig. 3.3-3 shows the circuit around the DC jack. Diode D1 protects the machine when a
wrong-polarity AC line adapter is connected. For the right polarity of the AC line adapter
plug, refer to Fig. 3.3-4.
Fig. 3.3-2 +5V Power Supply Circuit
Fig. 3.3-3 DC Jack-related Circuit
Fig. 3.3-4 Polarity of AC Line Adapter Plug
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