HP 412A Manual

1.
1-1. GENERAL.
1-2. TheModel 412A/
which covers the entire range of dc voltage, current, and resistance measurements normally encountered
in electronic equipment.
1-3. It measures voltages over the wide range of 0.02 millivolts to 1000 volts on thirteen ranges ar-
de
ranged in al, 3, 10 sequence from 1 mv full scale to 1000 v full scale. Overall accuracy on all thirteen
%
ranges Iswíthín ±1 of full scale. Voltage differences can be measured easily since the input circuit is
lated from the case and from the power line ground.
1-4. DAMAGE IN SHIPMENT.
1-5. Inspect and operate this instrument upon receipt. Section'I'V includes a performance check which
is a good test as part of incoming quality control inspection. The check can be made with the instrument
in its cabinet. If there is any damage, see the
manual.
1-6. POWER CABLE.
1-7. The three-conductor power cable supplied with this instrument terminates in a polarized three-prong
male connector recommended by the National Electrical Manufacturers' Association. The third contact
is an offset round pin added to a standard two-blade connector. This contact grounds the instrument when
used with an appropriate receptacle. An adapter should be used to connect the NEMA plug to a standard two-
contact output. When the adapter is used, the ground connection be comes a short lead from the adapter.
This lead should be connected to a suitable ground for the protection of operating
1-8. 115-230 VOLT OPERATION.
1-9. A switch located on the instrument rear converts the Model
230-volt, 50-60 cps power source. The switch changes the connection of the dual 115-volt primary windings
of the power transformer from a parallel combination to a series combination, or vice versa. Switch positions
are marked 115 and 230.
1-10. To convert the instrument from 115-volt operation to 230-volt operation, or vice versa, insert a
screwdri ver into the switch slot and slide the slot until the marking indicates the line voltage.
blade
At the time of the change, replace the line fuse. A
operation; a 0.4 ampere slow-blow fuse should be used for 230-volt operation.
CAUTION
Be sure the 115/230 V switch is set at the proper position before applying power to the instrument
Incorrect setting of the switch can result in damage to the instrument.
AR DC Vacuum Tube Voltmeter is a precision, wide range, multipurpose instrument
SECTION I
GENERAL DESCRIPTION
"Claírn for Damage in Shipment" paragraph at the back of this
412A/
6 ampere slow-blow fuse should be used for 115-volt
O.
personnel.
AR for use from either a 115-volt or
íso-