Epson PX-8 Technical Manual page 265

REV.-A
Table 6-6 MAPLE Board Test Points and Their Functions
Name
Function Remarks
GND Signal ground
VB+
Battery voltage
VB Backup voltage
Supply for 6kB V-RAM, 64kB
D-RAM, 7508 sub-CPU, and
A-D converter
+5 Logic circuit voltage supply - VB+ supply through
fuse F4 and transistor G6
VRF A-D converter reference voltage
Adjust to 2.0 V.
E 6303 slave CPU enabling signal
MC Microcassette tape read data signal
4.9M Clock signal halved from the primary frequency of
9.8304 MHz which is used as the control clock
signal for the LCD controller SED1320.
- -
MRG Issued from main CPU when D-RAM memory is
read/written or refreshed.
SP
Microcassette tape read data used as an output to
the speaker.
CL2 Keyboard Scanning clock signal Adjust the pulse cycle to 11.5
to 12.5 ms.
6.5.3 Variable Resistor Adjustments
There are four variable resistors, three on the MAPLE board (see Fig. 6-13) and one in the LCD
unit.
---VB+
- - - V B
Fig. 6-13 MAPLE Board Variable Resistors
6-10