32
Operation of the HM8143
5 Operation of the
HM8143
5.1 First time operation
Please observe especially the following notes:
❙
The line voltage indicated on the rear panel corresponds
to the available line voltage, also, the correct fuses for this
line voltage are installed. The fuses are contained in the
line voltage connector housing.
❙
The connection to the mains is either by plugging into a
socket with safety ground terminal or via an isolation
transformer of protection class II.
❙
No visible damage to the instrument.
❙
No visible damage to the line cord.
❙ No loose parts floating around in the instrument.
5.2 Turning on the HM8143
Turn on the instrument by operating the POWER button. Du-
ring power up the HM8143 automatically performs a selftest
routine, which checks all of the unit’s important functions
and the contents of the internal memories and registers.
While self-testing is going on, the instrument identification
and the version number of the firmware is shown on the two
displays (e.g. HM8143 1.15).
The values of the nominal output voltages and current limits
are stored in a non-volatile memory and are read back after
power-on. After turning on the HM8143, the outputs and the
functions TRACKING and FUSE are deactivated by default in
order to prevent damage being inadvertently caused to con-
nected loads because the stored voltage or current setting
might be too high for the application at hand.
From firmware version 2.40 the display refresh rate and the
baud rate are shown on the right display during the boot-
up prodcedure. For more information please see chapters
“Change of the baud rate“ and “Change of the display re-
fresh rate“.
Attention:
The HM8143 is not protected against reverse polarity!
For example, if you use the instrument in series operation the +
pole of the first output is interconnected to the - pin of the se-
cond output. To avoid damage of the instrument, make sure that
the circuit to be supplied is not shorted. Otherwise, the device
wired the wrong way and may be destroyed.
ATTENTION:
Do not switch off the instrument, while the output is still activa-
ted (LED of the OUTPUT button highlighted)! It may destroy your
device under test (DUT).
5.3 Turning off the button beep
The HM8143 offers the possibility to turn ON/OFF the but-
ton beep. While turning on the instrument keep the CUR-
RENT button of the right channel depressed to turn off the
beeper constantly. This setting will be stored inside the EE-
PROM. The button beep can be restored in the same way.
5.4 Setting output voltages and the current limits
The changeable parameters (output voltages and current
limit) are set using the rotary knob
8
. To change values,
first select the appropriate parameter with the
VOLTAGE
6
10
and CURRENT
7
9
buttons. Then use the rotary knob
8
to set the desired value.
If the outputs are on (OUTPUT LED
19
is on) the HM8143
displays will show the actual values, that means the po-
wer supply will show the measured values of voltage and
current (Vout and Iout). Operating the VOLTAGE
6
10
or
the CURRENT button
7
9
will switch the HM8143 to set-
ting mode, which is being indicated by glowing of one of
the LEDs above the buttons VOLTAGE
6
10
or CURRENT
7
9
. The corresponding display will show the nominal va-
lue of the output voltage or current limit. Now the desired
value of the output voltage or current limit can be adjusted
with the rotary knob
8
. This mode will be left after about
2 seconds after the last operation of the rotary knob. The
HM8143 will then display the measured values of the out-
put voltage and current again.
5.5 Trigger Input + Trigger Output (Start/Stop)
In order to permit easy triggering of an oscilloscope con-
nected to the output of the HM8143, especially in arbitrary
mode, the instrument is equipped with a BNC socket TRIG-
GER IN/OUT
22
on its rear panel. This is configured as a tri
-
state output and permits a trigger signal to be taken after
each signal period in arbitrary mode, or the arbitrary function
to be activated by an external trigger signal (TTL level).
5.6 Modulation inputs
By virtue of the modulation inputs MODULATION R/L
20
on the rear panel of HM8143, it can be also be used as a
modulation power amplifier. The input voltage is amplified
with factor 3. The frequency range (-3 dB) goes from DC to
50 kHz. The allowable external voltage ranges from 0 V to
10 V.
The output voltage of HM8143 will be the sum of:
V
out
= (V
modin
x 3) + V
set
If you are using the modulation, it is not allowed to use parallel
setup, otherwise the instrument may be destroyed.
Please note that the sum V
out
= (V
modin
x 3) + Vset
must not exceed the value of 30 V, as then the proper
functionality of the current regulation is not ensured
and the connected load can be destroyed.
