A multimeter is a voltmeter or an ammeter that can also measure
resistance in ohms or as continuity (presence of a complete circuit),
depending on a switch setting
•Note: always measure voltage and amps with electricity ON
•Measure resistance and continuity with electricity OFF
Autorange meter •Senses quantity of input and sets the range
accordingly
Otherwise you must change ranges on the meter to increase the
accuracy, and to keep from damaging it.Too much current can blow it up!
- Attach Leads (sometimes attach to different places depending on
usage)
- Turn Meter On
- Set to right usage: Volts, Ohms (Resistance or Continuity), or
Current (amps or milliamps) If you do not have autorange on your
meter you must set it manually to the largest value and then work
down.!
- Attach probes to hot leads: plus to plus and minus to minus for
DC! Or +Volts to + and – to ground, - Volts to – and + to
ground!
- Take reading.
- When done turn meter off!
Measuring Voltage Output to an AT System
Board
Measure voltage of each circuit
supported by power supply
Measuring Voltage Output to an ATX System
Board
1.
Try to determine what type of board and power supply connector
you have from the above graphics.
- Set
up a table and measure the voltage of each pin in the motherboard
connector.
- Record
it in the appropriate table below:
- Does
it match what should be there?
____________________________________________________________
- Does
this indicate a problem with the power supply?
- Measure
the voltage applied to a small (3.5 inch) drive connector
What is it ___________________________________________________
- Repeat
for a 5 inch drive connector.
What is it ___________________________________________________
- Turn
off the meter when you are done and return it to the cabinet.
- Replace
the case on your PC,
- Test
the PC to see if it still works
- Shut
down the PC, turn off the monitor.
|
ATX
Style Motherboard Power Connector
|
|
|
|
|
|
|
Connecter
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
|
Voltage
|
|
|
|
|
|
|
|
|
|
|
|
Connecter
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
19
|
20
|
|
Voltage
|
|
|
|
|
|
|
|
|
|
|
|
AT
Style Motherboard Power Connector
|
|
|
|
Connecter
|
1
|
2
|
3
|
4
|
5
|
6
|
|
Voltage
|
|
|
|
|
|
|
|
Connecter
|
7
|
8
|
9
|
10
|
11
|
12
|
|
Voltage
|
|
|
|
|
|
|
What conclusions can you draw as a result of this
lab?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
