13
Sous réserve de modifications / Reservado el derecho de modificación
Maintenance
The most important characteristics of the
instruments should be periodically checked
according th the instructions provided in the
sections “Operational check and “Alignment
procedcure. To obtain the normal operating
temperature, the mainframe with inserted module
should be turned on at least 60 minutes before
starting the test. The specified alignment procedure
should be strictly observed.
When removing the case detach mains/line cord
and any other connected cables from case of the
mainframe HM8001. Remove both screws on rear
panel and, holding case firmly in place, pull chassis
forward out of case. When later replacing the case,
care should be taken to ensure that it properly fits
under the edges of the front and rear frames.
After removal of the two screws at the rear of the
module, both chassis covers can be lifted. When
reclosing the module, care should be taken that
the guides engage correctly with the front chassis.
Operation of the module
Provided that all hints given in the operating
instructions of the HM8001 Mainframe were
followed especially for the selection of the correct
mains voltage start of operation consists practically
of inserting the module into the right or left opening
of the mainframe. The following precautions should
be observed:
Before exchanging the module, the mainframe
must be switched off. A small circle (o) is now
revealed on the red power button in the front centre
of the mainframe. If the BNC sockets at the rear
panel of the HM8001 unit were in use before, the
BNC cables should be disconnected from the basic
unit for safety reasons. Slide in the new module
until the end position is reached. Before being
locked in place, the cabinet of the instrument is
not connected to the protective earth terminal
(banana plug above the mainframe multipoint
connector). In this case, no test signal must be
applied to the input terminals of the module.
Generally, the HM8001 set must be turned on and
in full operating condition, before applying any test
signal. If a failure of the measuring equipment is
detected, no further measurements should be
performed. Before switching off the unit or
exchanging a module, the instrument must be
disconnected from the test circuit.
(1) DIGITAL DISPLAY
(7-segment LEDs)
The digital display indicates the measured value
with a resolution of 4
½
digits, the most significant
digit being used up to ”11”. The measured value is
displayed with correct point position and sign.
When DC values are measured, thedigitsare
preceded bya minus sign, if the positive pole of the
measured quantity is connected to the COMMON
input
(5)
. If the measurement range is exceeded
(>19999), the display flashes and displays ”0”, and
the buzzer beeps intermittently.
(2) mA
(pushbutton)
Function selection switch for current measure-
ments (AC and DC current).
(3) mA
(shock-proof socket for connectors of 4mm
diameter)
Connection (high potential) forAC and DC current
measurements in combination with the COMMON
input (low potential). The input is fuse-protected.
(4) k
Ω
Ω
Ω
Ω
Ω
(pushbutton)
Function selection switch for resistance
measurements.
(5) COMMON
(shock-proof socket for connectors
of 4mm diameter)
The COMMON socket (low potential) serves as a
common connection for all measurement functions,
to which the earthy potential of the measured
quantity is applied. This input is connected with
the internal shielding of the set.
The voltage across this terminal with respect
to the cabinet (non-fused earthed conductor,
ground) should not exceed 500V to ensure
safety of operation.
(6) k
Ω
Ω
Ω
Ω
Ω
(pushbutton)
Function selection switch for voltage measure-
ments (AC und DC voltage).
