Epson PX-8 - Page 79

REV.-A
2.4.4.1 Sub-CPU 7508 Clock Signal Oscillator Circuit
This circuit oscillates at a frequency of approximately 200 kHz, using an external capacitor and
the variable resistor VR3.
The
output signal waveforms should be observed at the indicated points as in Fig. 2-57.
5V
5V
7508~
pin 19 G
7508~
pin 21 G
5V
Fig. 2-57 7508 Clock Signal Oscillator Circuit Output
Signal Waveforms
2.4.4.2 A-O Converter Clock Signal Oscillator.
This circuit oscillates at a frequency of approximately 480 kHz using an external capacitor and re-
sistor. The signal
waveforms at the indicated points should be observd as shown in Fig. 2-58.
5V 5V
1D
pin8~
G--- _______________ ~~~~~~~-I __ ~_L __ __
1D
~n-7 ...I-.I....D ~QllO~nn~n~n~I
5V
Fig. 2-58 A-O Converter Clock Signal Oscillator Waveforms
2-55