Epson PX-8 - Page 47

REV.-A
Major actual voltage waveforms are shown below.
(1) Top - Test point:
IC 140, pin 14
(2) Center - Test point: IC 140, pin 15
(3) Bottom - Test point: Diode 01, cathode
2V 5V
G
G---------------
G JC7uuTu:U~uT
5V 5V
Fig. 2-16 Major Voltage Waveforms In +5V
Regulator Circuit
Details of the above waveforms are enlarged below for clarity.
5V
5V
G
U
u
IJ
G
f
r--
Voltage circuit - - - --
5V
5V
GND - - - - ---
Fig. 2-17 Major Voltage Waveforms Enlarged
Though
it looks as if 05 continued to oscillate due to false images in the above photograph, it ac-
tually switches once almost every several
switching clock pulses. This ratio varies depending on
load.
2-23