NEC PC-8201 Service Manual page 86

d)
Is the voltage power supplied to each pin of CNl?
If the voltage is not supplied to these pins. the
power board is bad.
6.2.2 PC-8201 Abnormal Reset
bymproms
Always at reset state.
(CN 1 (P9) keeps
"L"
level.)
a)
If CN (PIO) is less than 7.5 V power. U2. Q l 6 , C1. or D7 of power board are bad.
b)
I f the collector of Transistor 7- is not "L" level. transistor 2 is bad.
n
symptoms
Reset is not enabled at power-on.
a)
When pushing a reset switch. if reset does not operate, the reset switch is bad.
b)
Check the collectors of transistors 2 and 1 .
6.2.3 PC-8201 Abnormal CPU (80C853
Symptoms
The CPU does not operate.
*
See Item 5.1.3 "CPU (80C85) Operation Test".
If you can verify following
abnormalities,
exchange the CPU board.
(1) Causes:
a)
KESET (P36) is "L" Icvel.
b) READY is
"L"
level.
C)
Clock keeps
"L"
level or
"H"
level.
(See Item 5.1.3 "CPU Clock Operation Test".)
6.2.4 Abnormal CPU Clock
The CPU does not operate.
I