Digital Multimeter
A digital multimeter, as shown in Figure 1, is a device that can take many types of measurements. It tests the integrity of circuits and the quality of electricity in computer components. A digital multimeter displays the information on an LCD or LED.
Loopback Adapter
A loopback adapter, as shown in Figure 2, also called a loopback plug, tests the basic functionality of computer ports. The adapter is specific to the port that you want to test.
Toner Probe
The toner probe, as shown in Figure 3, is a two-part tool. The toner part is connected to a cable at one end using specific adapters, such as an RJ-45, coaxial, or metal clips. The toner generates a tone that travels the length of the cable. The probe part traces the cable. When the probe is in near proximity to the cable to which the toner is attached, the tone can be heard through a speaker in the probe.
External Hard Drive Enclosure
Although an external hard drive enclosure, as shown in Figure 4, is not a diagnostic tool, it is often used when diagnosing and repairing computers. The customer hard drive is placed into the external enclosure for inspection, diagnosis, and repair using a known-working computer. Backups can also be recorded to a drive in an external enclosure to prevent data corruption during a computer repair.