Epson PX-8 - Page 78

REV.-A
2.4.3 Voltage Regulator Oscillator Circuit
This circuit is a CR oscillator circuit, consisting of the resistor R90 (68 kohms) and the capacitor
C26 (220 pF), oscillates at a frequency of approximately 35 kHz. The output is amplified by IC
14D and supplied to the following three circuits:
a. RS-232C DC-DC converter circuit
b. LCD DC-DC converter circuit
c. ROM capsule biasing circuit
R21 1 K 140
140
5
C26 220P
140
2
11
R90 6BK
12
To each circuit a though c
discribed above
Fig. 2-55 Voltage Regulator Oscillator Circuit
5V
10j.lS
IC 14D
Pin 11
D D
D
[
G
IC 14D
Pin 7
D
r::,
r::,
r
G
5V
Fig. 2-56
2.4.4 Other Oscillator Circuits
Sub-CPU 7508 and AID converter have own CR oscillator by using the external components.
Sub-CPU clock is adjustable with VR3.
2-54