Model 405'2 Sect.1 Page 1
GENERAL DESCRIPTIO
1-1 IDENTIFICATION parallel combination to a series combination. See
the schematic diagram for details. At the time of
The 63 Model 405C Automatic DC Digital Voltmeter
measures positive or negativevoltages from 1 milli- conversion, change the line fuse from a 2-ampere,
slow-blow type to a 1-ampere, slow-blow type.
volt to 999 volts. It can select range and polarity
automatikally to display voltages from 100 milli-
i volts to 999 volts to three significant figures. 1-5 THREE CONDUCTOR POWER CABLE
~ :' This instrument is equipped with a three conductor
1-2 COOLING power cable terminated with a polarized connector
The 405C uses forced-air cooling to maintain tol- recommended by the National Electrical Manufac-
turers' Association (NEMA). The third green
erable temperatures within the cabinet. Exhaust
fan and air outlet are located on the instrument rear conductor is terminated in a round pin added to a
air intakes, on the sides. Allow at least 2 in. clear- standard two-bladeconnector. With the NEMA con-
ance about instrument sides and rear for proper nector plugged into an appropriate receptacle, the
ventilation. third lead grounds the instrument cabinet for the
protection of operating personnel. To use the NEMA
connector in a two-contact receptacle, you should
1-3 STEPPING SWITCH
use a three-prong to two-prong adapter. The ground
The 405C uses a relax-operated stepping switch lead emerges from the adapter as a short green lead
for ranging. Although the switch requires infre- which should be connected to a grounded receptacle
quent service, it is important to -service it when box.
due. See Section IV, Maintenance.
1-6 DAMAGE IN SHIPMENT
1-4 POWER LINE VOLTAGE
Inspect and operate this instrument upon receipt.
The405C is normally wired for use from a 115-volt, Section IV contains a performance check which is a
50-60 cps power source. To convert it for use from good test as part of incoming quality control inspec-
a 230-volt power source, change the dual 115-volt tion. If there is any damage, see the"C1aim ?or
primarywindings of the power transformer from a Damage in Shipment" sheet in this manual.
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i
Figure 1-1. Model 405CR Automatic DC Digital Voltmeter
00518- 2 |
ACEC
