Hardware Reference
In-Depth Information
Figure 13.19
Layout of the controls and adjustments of a typical digital
multi-meter
A typical application for a multi-range meter is that of checking the various
supply voltages present within the PC. For an operational system the supply
voltages should be within the range given below:
Acceptable value (V)
Nominal
value (V)
Minimum
Maximum
+
5
+
4.75
+
5.25
−
5
−
4.75
−
5.25
+
12
+
11.4
+
12.6
−
12
−
11.4
−
12.6
Multi-range meters may also be used for checking the voltages present on
the supply rails within individual expansion cards. Particular points of interest
will be those associated with the supplies to individual chips. In such cases, PC
bus extension card frames can be employed in order to gain access to a 'live'
expansion card. Alternatively, the expansion card in question can be fitted to
the left-most slot within a PC in order to provide access to the printed wiring
of the card.
Multi-range meters may even be used to display logic states on signal lines
which remain static for long periods. This is often the case when dealing with
