Rosewill Computer Case 422 Technické informace stáhnout pdf (Strana 94)

177

Exercises

Disassembly

and Power

6. Remove both leads from the wall outlet.

7. Insert the meter’s black lead into the smaller flat (hot) AC outlet plug.

8. Insert the meter’s red lead into the larger flat (neutral) AC outlet plug. The meter reading

should be around 120 volts. Use Table 4.9 to record the reading.

9. Plug the computer power cord into the AC wall outlet that was checked using Steps 3

through 8.

10. Verify the other end of the power cord is not plugged into the computer.

11. Perform the same checks you performed in Steps 3 through 8, except this time check the

power cord end that plugs into the computer. Use Table 4.10 to record the reading.

Table 4.10 Power cord AC checks

Connections Expected voltage Actual voltage

GND to hot 120VAC

GND to neutral 0VAC

Hot to neutral 120VAC

12. If the voltage through the power cord is correct, power off the meter. Notify the instructor

of any incorrect voltages.

Instructor initials: _____________

Lab 4.9 Device DC Voltage Check

Objective: To check the power supply voltages sent to various devices

Parts: Multimeter

Computer

Procedure: Complete the following procedure and perform the accompanying activities.

1. Set the multimeter to DC VOLTAGE (refer to the meter’s manual if unsure about the

setting).

2. Power on the multimeter.

3. Power off the computer.

4. Remove the computer case.

5. Locate a Molex or Berg power connector. If one is not available, disconnect a power con-

nector from a device.

6. Power on the computer.

7. Check the +5 volt DC output from the power supply by placing the meter’s black lead

in (if the connector is a Molex) or on (if the connector is a Berg) one of the grounds* (a

black wire). Place the meter’s red lead on the +5 volt wire (normally a red wire) in or on

the connector. Consult Figure 4.39 for the layout of the Molex and Berg power supply

connections. Figure 4.39 also contains a table with the acceptable voltage levels.

* Use and check both ground connections (black wires going into the connector); do not

check all the voltages using only one ground connection.

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Rosewill Computer Case 422 Technické informace Strana 94