Every technician should have a good tool
set. In order to correctly troubleshoot hardware problems, technicians
will need to be equipped with the right tools. The average computer
problem is not going to require sophisticated tools. Usually a
screwdriver and a nut driver are all that is required. However,
technicians should be prepared for a wide range of circumstances. The
tools in a good tool set include both mechanical and digital tools.
Technicians should plan ahead if they are going to work away from
their tech-bench, and bring the necessary tools. The typical tool set
will include several items:
Figure
A wide variety of flat-head and Phillips-head screwdrivers should be carried in a technician's tool set. Technicians can expect to encounter a wide variety of screws and nuts. Also, the position of certain screws might require different lengths of screwdrivers, and an ill-prepared technician might be hindered. Technicians will be working with wiring and cabling on a daily basis. Sometimes, a wire or cable will need to be cut. Diagonal or crosscut pliers allow the technician to precisely cut wires and cabling to their specifications. A good tool set should also include a small standard socket that is set to accommodate hex head screws. Also, a mirror will help to see into tight spots or corners. Digital Multimeter A DMM combines the functionality of a voltmeter, ohmmeter, and
an ammeter into one easy to use device. A DMM can measure voltage,
amps, and ohms in both alternating and direct current. A DMM can
be used to test power supplies, DC/AC voltage and polarity,
resistance (Ohms), diodes, continuity, coaxial cable, fuses, and
batteries. Figure
The DC Voltage Test is used to test live DC circuits. This test is most often performed on motherboard circuits. The test should be conducted in parallel with the circuits. A parallel test is performed on a circuit by connecting it to the red (measuring) lead and connecting the black (reference) lead to the ground.
A Resistance, or Continuity Test, is another test performed by a DMM. It is performed to verify that a device or conductor has zero resistance. For example, resistance tests are performed to test fuses. First, the technician must disconnect one end of the fuse from the system. Setting the DMM at 1 ohm, a good fuse should read close to 0 ohms. If the fuse is bad, the reading will be to infinite. A resistance test should never be conducted when the power is turned on. Turn the power off before performing a resistance test. Serious damage to the technician and meter can happen if the power is turned on. Also, before resistance testing can be conducted on a circuit, it must be removed from the system. Isolating a component from the system board can be accomplished by unsoldering one or both ends of the circuit. Another common way to use the DMM is to set it to produce a sound when no resistance is detected (continuity exists). This is typically used to test continuity in suspect RAM modules. Unplug the module from the motherboard, set the DMM to make a sound when it detects no resistance and then using the red and black probes, touch both end-pins of the module simultaneously and listen. Hearing a sound indicates continuity. If there is no sound, the chip is most likely "dead". The AC Voltage Test is also used for checking system components. Testing power supplies is the main use of AC voltage test. Use extreme caution when testing power supplies. The electrical current supplied by a power supply unit can be dangerous to the technician. Also, ripple voltage from the DC output can be tested with the AC voltage function. Loop Back Plugs
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shows
an example of a typical lab tool set.
is a list of important terms that should be reviewed before
discussing a DMM.
is a DMM.
