Husqvarna DM 650 Workshop Manual page 24

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Insulation testing 1,000 volts
Measure against phase pins K, A and B
and earth point
Earth continuity testing
Measure against earth pin C
and earth point
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TROUBLESHOOTING
Signal cables, connection testing and insulation testing
This test is used to check whether any cable is broken and whether
there is any damaged insulation which is causing the wires to come
into contact with one another.
This test is carried out with a multimeter set for connection
testing with a buzzer signal. The cabling does not need to be
removed from the machine for this test.
Test methodically. The easiest way to proceed is to start from the
rectangular connector. Place the first test pin in any terminal. Use
the second test pin to test against all pins in the round contact. If
the cabling is intact, there must be a connection with one of the
pins, but not with any of the others. Proceed using the same
method to test the other cables. Note that there are pins with no
cable connections: see the wiring diagram on page 18.
There is very little likelihood of any of the signal cables coming
into contact with the motor cables due to damaged insulation, but
this can be tested by also including the motor's connector in the
test.
Display card
If the HF unit and cabling are complete, the drilling machine's
display must be shown. If the information "UNKNOWN UNIT"
is displayed, the display unit is defective. If this is the case, replace
it.
Note: Even if the display shows communication between
the drilling machine and the HF unit, this is not proof that the
cabling between the two is fault-free.
Switch
The main switch and push button for low speed (used when rein-
forcement bars are used in concrete) can be easily tested using a
multimeter. Check that the switches open and close the circuit
board in the intended way.
Insulation and earth continuity testing
IMPORTANT
Legislation on insulation and earth continuity testing differs
from country to country. Hence it is important to find out
about applicable regulations in the country in which the
service is carried out.
These safety tests are the last things done when the service actions
have been completed and the machine has been reassembled.
Insulation testing
Measure with 1,000 volts between an earthed metallic part which
can be touched and the phases (K, A and B) of the contact. There
must be no current flowing between earth and the phases (max.
ohm value).
Earth continuity testing
Earth continuity testing shows that the machine's earthing is fault-
free. Set the instrument for continuity measurement. Current must
flow between an earthed metallic part which can be touched and
the earth pin C of the contact (min. ohm value).