Making Measurements - TTI 1604 Manuel D'instructions

Scale Length
The scale length is always ± 40,000 counts, except AC ranges which are ± 4,000.
Function Selection
All functions are directly selected by pressing the appropriate function keys (e.g. V followed by
DC to set DC Volts). Changing function sets autorange when there is more than one range;
providing the appropriate function has been selected (e.g. Ω for resistance measurement) and the
parameter to be measured is within the range of the meter, a valid reading should always be
shown.
The units and function are shown in the display (e.g.
to indicate autorange.
Continuity and Diode Test and selected by pressing SHIFT followed by the appropriate key. The
associated annunciator confirms the selection. Continuity sets the meter to the 4kΩ range and
buzzes for values below approximately 10Ω.
Range Selection
Selecting a new function always sets autorange to ensure an in-range reading is made with
maximum resolution whenever possible; the meter ranges up at 40,000 counts (4,000 on AC
ranges) and ranges down at 3,840 counts (V and Ω) or 255 counts (mA); AC ranges range down
at 384 counts and 25 counts respectively.
There are, however, situations when it is desirable to lock the range; for example, to stop the
meter autoranging to the 40MΩ range and back between successive resistance measurements of
lower resistance values, or to set a lower resolution range when an unstable parameter is being
monitored. To lock the range, change from auto to manual ranging, see below.
Manual range changing is selected either by alternate presses of the Auto/Man key, which locks
the meter in its present range, or by using the arrowed up/down keys which both change the
range and lock the meter in that new range. The Auto annunciator is off in Manual mode.
Overrange is indicated by OFL in the display; overrange is shown when the count exceeds
40,000 in a manually locked range (1024V/768V on the 1000VDC/750VAC ranges respectively).
Autoranging can be restored by pressing the Auto/Man key again.
Making Voltage Measurements
Voltage measurements are made using the red V/Ω socket and the black COM socket having
selected the appropriate function and range as described above.
The meter will show a minus sign (on dc measurements) when the voltage applied to the red
socket is more negative than that applied to the black socket.
Note that when AC voltage ranges are selected with the meter inputs open circuit a non-zero
reading will usually show because stray AC signals couple into the meter's high impedance input.
This is perfectly normal and will not affect the accuracy of practical voltage measurements where
source impedance is generally low.
The maximum voltage that can be applied between V/Ω and COM is 1000V DC or 750V AC
(265V DC/AC rms on 400mV range), Category I; damage to the instrument may result if this limit
is exceeded.
WARNING! The maximum input voltage to ground must not exceed 1000V (Category I) or 600V
(Category II) dc or ac rms. Safety will be impaired if these ratings are exceeded, see Safety
section at the beginning of the manual.
12

Making Measurements

and V for DC Volts) together with Auto