MiTAC 7521 PLUS/N User Manual

129

An error occurs when a mouse or other I/O device is installed.

SIO TEST ERROR

1. Check if the mouse or others I/O device are  

installed (

J507

) properly.

(Including driver)

2. Check if CMOS COM port setting correctly.

Test

OK?

Re-test

OK?

Change M/B or go

into board-level

Troubleshooting.

NO

YES

Correct 
it and end.

YES

NO

Change the
faulty part
and end.

Board-level

Troubleshooting for

SIO test error.

Check the following parts for cold solder or one of the following 
parts on the mother-board may be defective, use an oscilloscope
to check the following signal or replace the parts one at a time and 
test after each replacement.

Parts:

U27,U1
Q1,R1

J507

Signals:

ISA_IRQ4                  
RS232_OFF#
D/RI#
D/DTR#
D/CTS#
D/TXD
D/RTS#
D/RXD
D/DSR#

Try another known good I/O device.

D/DCD#
COM1DCD#
COM1DSR#
COM1RXD
COM1CTS#
COM1RTS#
COM1TXD
COM1DTR#