NEC PC-8201 Service Manual page 88

6.3.4 Abnormal RS-232C lnterface
*
See Item 5.2.4 "RS-232C lnterface Operation Test".
If you car1 verify following abnormalities, exchange the CPU board.
a)
If something is abnormal when executing the RS-732C operating test program (when
"RS-232C ERROR" is displayed). U30. U31. U21. U19. or U22 are bad.
6.3.5 Abnormal SlOl lnterface
*
See Item 5.2.5 "SIOI Interface Operation Test".
If you can verify following abnormalities. exchange the CPU board.
a)
If something is abnormal when executing the SIOl interface operating test program
(when "SIO 1 ERROR" is displayed). U25, U19. U2 1. o r U22 are bad.
6.3.6 Abnormal Printer lnterface
*
See Item 5.2.6 "Printer Interface Operation Test".
If you can verify following abnormalities, exchange the CPU board.
a)
If the data signal (PDBO to PDB7) is abnormal. confir111 the signal in U28 and in
u35.
If they are normal, the printer bus connector is bad.
If they are abnormal, U28 or U35 are bad.
b)
If PSTB signal is abnormal, confirm the signal in U12 (P2).
If it is normal, the printer bus connector is bad.
If it is abnormal. U12 is bad.
c)
If BUSY signal is abnormal, confirm the signal in U18 (P39).
If it is normal, the printer connector is bad.
If it is abnormal, U 18 is bad.
6.3.7 Abnormal Audio Cassette lnterface
*
See Item 5.2.7 "Audio Cassette Interface Operation Test".
If you cannot verify the correct signal when executing the audio cassette interface
operating test program, thc cause is listed below.
a)
If REh.I+ and IZEhl- are opened while REh1 is operating. R L (relay) is bad.