14 PORT FAILED (LPT, COM1, COM2), 22 USB FAILED

A. 14 PORT FAILE D (LPT, COM1, COM2)

1. COM1, COM2 FAILED

1.1 查CHIP至I/O CHIP (877 or 977) 之IRQ3 (COM2), IRQ4 (COM1) 之信号是否正确

1.2 查I/O之BUFFER (75232 or 75185) 之+12V or –12V是否有输入或所接之保护二极管是否OPEN

1.3 查I/O CHIP (877 or 977) 至75232 or 75185和75232 or 75185至COM1, COM2之Connector线路是否OPEN or SHORT or Connector不良

1.4 查COM1, COM2所接之电容或排容是否SHORT or 错件和I/O CHIP所接之电阻是否错件

2. LPT FAILED

2.1 查CHIP至I/O CHIP (877 or 977) 之IRQ7 之信号是否正确

2.2 查I/O CHIP (877 or 977) 所接之电阻或排阻 (电容或排容) 是否SHORT or OPEN或不良

2.3 查I/O CHIP (877 or 977) 至LPT Connector之线路是否OPEN or SHORT or Connector不良

B. USB FAILED

1. 查USB Connector所连接之USBP0+, USBP0-, USBP1+, USBP1-至CHIP之线路是否OPEN or SHORT

2. 查USB Connector所连接之电阻 (排阻) ,电感, FUSE是否OPEN or SHORT or错件或不良

3. 查USB Connector所连接之VCC, GND是否有输入

4. 查CLOCK CHIP之48MHZ是否有输出至CHIP或频率是否正确