Test Products International 460 - Manual (Page 44)

1. The bandwidth of the 460 is 20 Mhz. Not all probes have this much bandwidth. If you
use probes with lesser bandwidth, the measurements and waveform interpretation may
be inaccurate. Check the specifications of the probes you receive before using them.
2. The ground potential in the shield of most co-axial type probes is the same potential as
the “Common” potential. This means that if you use the convenience ground outlet in
the body of many probes, it will have the same effect as using a separate wire from the
“COM” outlet of the 460.
3. The normal attenuation in probes is, for all practical purposes zero, these are the
probes referred to as 1:1 probes. Another commonly used probe is the 10:1 probe.
The 10:1 probe is attenuated (sometimes switchable) to read only one tenth (1/10th) of
the potential that the probes detect at the probe tips. The 460 has an internal ability to
read 10:1 probes correctly, as long as the instrument is correctly set (SCOPE > F1 > 10:1
> ENTER) . Note that you can set up the two channels of the 460 for different probe
sensitivities.
4. The 10:1 probe requires a minor adjustment (because of the internal attenuation circuit)
whenever you set the probe up, or use the same probe on a different channel. This
adjustment is so that the displayed waveform will accurately represent the shape of the
waveform being measured. The adjustment is usually made via a trimmer (variable
capacitance) in the head of the adapter at the instrument end. Refer to Chapter 4 (10:1
Probe Compensation Adjustment), for instructions on making the adjustment.
Battery Check and Replacement
The 460 uses a rechargeable 4.8V Ni-MH battery (4-cells @ 1.2V, 3Ah). The battery should last
through many recharges before losing the capacity to hold a charge. Should the latter case hap-
pen, the best option is to replace the battery. The following steps will guide you through this
process.
Disassembly:
1.
Disconnect the power charging plug and all connectors and cables. Then check that
power for the instrument is off. If the battery compartment cover is hot, you may wish
to let the instrument cool before performing the next step.
2. At the back of the instrument, remove the two screws near the base of the support flap.
3. Turn the instrument over so that the battery cover and battery fall into the palm of your
lowest hand. If they do not come out on their own, give a slight up and down shake to
the instrument. However do not use excessive force.
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460 User s Guide Maintenance