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1 INTRODUCTION
1.1 General Description
The Simpson Volt-Ohm-Milliammeter 260 Series 8, (hereafter referred to as the
260 or as the Instrument) is a rugged, accurate, compact, easy-to-use Instrument
equipped with mirrored dial to eliminate parallax. The Instrument can be used to
make accurate measurements of AC and DC voltage, direct current, resistance,
decibels, and Output Voltage. The Output Voltage function is used for measuring
the AC component of a mixture of AC and DC voltage. This occurs primarily in
amplifier circuits.
New Features in the 260-8 are:
0-25V AC/DC Range
Mirrored Dial
1.2 Overload Protection
No single protective device nor even a combination of devices as found in the 260
can fully protect a multi-purpose Instrument under all overload conditions. Over-
loads of such severity as to damage the Instrument despite all the built-in protec-
tion provided are possible when the Instrument is misused. The 260-8 has been
designed to afford maximum instrument protection under overload conditions which
might occur within the measuring capabilities of the Instrument, however, the op-
erator must exercise care to avoid severe overloads, particularly when working in
high voltage circuits.
Basic overload protection is provided by a small inexpensive and easily obtain-
able 3 AG type, 1 Amp, quick-blow fuse. This fuse is rated to interrupt circuit
voltages up to 250 V. For maximum protection it is important to replace the 1A
fuse with the Littlefuse type 312001 only.
A supplemental high energy fuse is provided for additional protection from severe
overloads. This fuse is rated for an interruption capacity of 10,000 Amps up to
600 V. (Littlefuse Type BLS or Bussman Type BBS). If the Instrument fails to
indicate a reading, the 1 Amp or the 2 Amp fuse may be burned out. (Refer to
paragraph 5.4 for fuse replacement.) A 1 Amp spare fuse is furnished with each
Instrument. Fuses are located in the battery and fuse compartment.
NOTE: The 0-10A range is not fused. The shunt connects directly to
the –10A and +10A jacks.
Two diodes connected across the meter movement affords protection to the move-
ment by circumventing excessive current around the movement in the event of an
overload.
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