NEC PC-8201 Service Manual page 87

If you can verify following abnormalities, exchange the CPU board.
a)
When you cannot verify the correct signal a t U17 (P37).
b)
If there is no signal a t U 17 (P 1. P?,). then U 17. the crystal transmitter. C12. o r C 1 1
are bad.
6.2.5 Abnormal Calendar Clock
*
See Item 5.1.5 "Calendar Clock Operation Test".
If you can verify following abnormalities. exchange the CPU board.
a)
If you cannot verify the correct signal in U10 (P 10). then U 10 is bad.
6.3 1/O Peripheral Circuit
6.3.1 Abnormal LCD
Display
*
See Item 5.2.1 "LCD Operation Test".
If you can verify following abnormalities. exchange the LCD board.
a)
If you can verify the correct signal a t the LCD connector. the LCD board is bad.
b)
If the correct signal is not at the LCD connector. U18, U42, U23. U16. U?. U3, U4.
US. U17. o r U14 are bad.
6.3.2 Abnormal S102 Port
*
See Item 5.2.2 "SI02 Port Operation Test".
If you can verify following abnormalities. exchange the
CPU
board.
a)
If something is abnormal when executing the general port operating test program
(when "SIO ERROR" is displayed). U25. U21. o r U22 are bad.
6.3.3 Abnormal BCR Interface
*
See Item 5.2.3 "BCR Interface Operation Test".
If you can verify following abnormalities. exchange the CPU board.
a)
If something is abnormal when executing the BCK operating test program (when
"BCR ERROR" is displayed). U27 is bad.