Microcassette Tape Drive Adjustment - Epson PX-8 Technical Manual

REV.-A
Table 6-7 Variable Resistors and Their Functions
Loca-
Name Function
tion
VR1 Speaker sound level adjustment
MAPLE
VR2 A-D converter reference voltage
Board
VR3 7508 sub-CPU clock signal adjustment (for keyboard scanning)
LCD VR LCD view angle adjustment
VR2 and VR3, listed in the Table 6-7 need to be adjusted as follow:
(1) VR2
Adjust the voltage across the VRF terminals to 2.0V with VB+ at 5.0V.
(2) VR3
Adjust the cycle of the pulse signal at point
"CL2" or Pin 21 of IC "2E" to 200 kHz
±4%.
6.5.4 Jumper and DIP Switch Settings
When a computer board is replaced, set the jumpers and/or DIP switches according to the follow-
ing;
(1) Jumpers
Set the jumpers by referring to the old board as well as the descriptions in 2.5, "Jumper and
Switch Setting" paying attention to the following:
J1: The J1 setting varies depending on the type of main CPU (.uPD 70008). Examine the main
CPU chip (4A) on the new board before setting J 1 .
J5: Use the same setting as the old board, A or B. If a different terminal is wired, ghost dis-
plays may appear on the LCD panel.
J2 and J4: Use the same settings as on the old board. The user may use other than the stan-
dard setting.
J3: Always use the standard setting; open or OFF.
(2) DIP switch (SW4)
Set the individual switches of this DIP switch assembly according to the descriptions in 2.5
"Jumper and Switch Setting".
6.6 Microcassette Tape Drive Adjustment
The microcassette tape drive requires two regular adjustments, reel torque and azimuth.
However, the test tapes have no directory area and cannot be read by the normal LOAD instruc-
tion, resulting in a message, "DEVICE UNAVAILABLE". Therefore the drive must be manually
operated as follows:
6-11