Hameg HM 203, Руководство пользователя

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Pay attention to the usual caution with single MOS-
components relating to static charge or frictional elec­
tricity!
In-Circuit Tests
Caution! During in-circuit tests make sure the circuit is
dead. No power from mains/line or battery and no
signal inputs are permitted. Remove all ground con­
nections inclusive Safety Earth (pull out power plug
from outlet). Remove all measuring cables inclusive
probes between oscilloscope and circuit under test.
Otherwise the connection o f both CT test leads is not
optional.
In-circuit tests are possible in many cases. However,
they are not so well-defined. Caused by shunt connection
of real or complex impedances — especially if they are of
relatively low impedance at 50 or 60Hz — to the compo­
nent under test, often great differences result compared
with single components. In case of doubt, one compo­
nent terminal may be unsoldered. This terminal should
then be connected to the insulated
CT socket avoiding
hum distortion of the test pattern.
Another way is a test pattern comparison to an operating
circuit with the same circuit diagram (likewise without
power and any external connections). Using the test
prods, identical test points in each circuit can be
checked, and a defect can be determined quickly and
easily. Possibly the device itself under test contains a
reference circuit (e. g. a second stereo channel, push-
pull amplifier, symmetrical bridge circuit), which is not
defective.
The test patterns on page M l 3 show some typical
displays for in-circuit tests.
Maintenance
Within the context of maintenance, it is recommended
that the most important characteristics and criteria of the
HM203 be periodically checked. The following Test In­
structions indicate only those tests, which can be per­
formed without the
use of expensive ancillary
instruments.
Accessories
Each HAMEG oscilloscope is supplied with an Instruction
Manual only. However, a wide range of accessories,
which include test cables and probes, are available and
should be ordered according to the particular application.
M l 2 20 3-4