Note that the serial and parallel port tests are more thorough if you connect a loop-back connector to the port before running the test for that port. See the wiring diagrams below.

5 9

16

13

25

These connections are not used.

Diodes are 1N4004

or equivalent

(IF=1A, VF=1V@1A,

VR=30-400V)

1 14

Figure 3-3. Serial and Parallel Loopback Connectors

HP Omnibook 500

Troubleshooting and Diagnostics 3-21