8
1.3
Internal Batteries
There are two batteries in the ohmmeter circuits, a NEDA 13F size D cell that
furnishes 1.5-volts for the R x 1 and R x 100 ranges and a NEDA 1604 battery that
furnishes 9-volts for the R x 10,000 range.
1.4
Printed Circuit
Most of the component parts are mounted on a printed circuit board which simpli-
fies assembly and maintenance, thus extending the useful life of the Instrument.
1.5
Phenolic Case
The Phenolic case is designed with heavy reinforced walls for maximum durabil-
ity and provides excellent protection for the circuit components. The case also
has an externally accessible battery and fuse compartment. Access to the batter-
ies and fuses is obtained by unscrewing a single captivated screw at the bottom
of the case and sliding out the compartment cover.
1.6
Adjust-A-Vue Handle
A carrying handle is attached to the Instrument case. The handle may be used to
support the Instrument in a convenient sloping position for easy viewing. The
case can also be placed either vertically or horizontally. The horizontal position is
preferable for greater accuracy since the Instrument is calibrated in this position.
1.7
Test Leads
Each Instrument is furnished with one pair (Catalog Number 00043) of probe
type test leads (one red and one black, each 48 inches long) for all applications
of the Instrument. These test leads have elbow prods on one end to connect the
leads to the recessed jacks on the Instrument front panel. The probe tips at the
opposite end have threaded shoulders to accept the screw-on insulated alligator
clips (furnished with the test leads) or the 5000 volt test probe(s) to extend the
Instrument AC or DC voltage range. The test leads and the insulated alligator
clips are rated for the voltage and current ranges available on the 270. Maximum
ratings are 1000 V AC or DC or 10 DC amperes. These ratings for the test leads
must not be exceeded in any application.
1.8
Technical Data
Table 1-1. Technical Data
1. DC VOLTS:
Ranges:
0-1-2.5-10-50-250-500-1000V
Sensitivity:
20,000V per volt
2. DC MILLIVOLTS:
Range:
0-250mV
Sensitivity:
20,000V per volt
3. AC VOLTS:
Ranges:
0-2.5-10-50-250-500-1000V
Sensitivity:
5,000
⍀
per volt
25
5.
OPERATOR SERVICING
The following paragraphs describe the battery replacement, fuse replacement,
test lead inspection and care for the 270-5.
5.1
Inspection
The user is protected from electrical shock by the insulation of the 270 and its test
leads. Frequently examine the 270 and its test leads for insulation damage. Check
for cracks, cuts, chips, burns or deterioration that expose internal metal parts or
reduce the spacing between such metal parts and hand contact.
Make certain that the battery compartment cover is securely fastened in place
before the Instrument is used.
Do not permit an Instrument with a broken glass meter cover to be used.
Whenever the battery compartment cover is removed for any reason, check that
the proper fuses are being used.
Severe overloads may have damaged the Instrument’s circuitry despite the pro-
tection afforded by the fuse. When a fuse is replaced, all ranges should be
routinely checked (calibrated) against the specifications in this manual before
the Instrument is returned to service.
5.2
Battery Replacement
Batteries should be replaced before their useful life has expired. Failure to do so
may result in battery leakage and corrosion.
SPARE 1A FUSE
2A FUSE
9V BATTERY
1A FUSE
Figure 5-1. Battery and Fuse Compartment
Содержание 270 Series 5
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