English - 53
Repair Instructions
7.21 Handle heater and carburettor
heater
(550XPG, 550XPG TrioBrake)
Certain chain saw models can be tted with a han-
dle heater and a carburettor heater and comprise
the following:
• Generator
• Power switch
• Heating element in the rear handle
• Handle bar with heating element
• Carburettor heating element
• Thermostat
Troubleshooting
It is possible to troubleshoot with most parts tted
to the chain saw. Troubleshooting requires:
• Ammeter
• Ohmmeter
• Coolant spray
Oxidation of the connectors in the heating
elements in the rear handle and the power switch’s
contact plate is the most common fault.
Troubleshoot as follows:
1
Loosen the screw holding the earth cable. See
Figure 1.
Fig 1
Fig 3
3
Unscrew the two screws on the front handle and
remove the cover. See Figure 3.
2
Measure the resistance in the whole circuit by
connecting the multimeter to the earth cable and a
properly cleaned cylinder. See Figure 2.
A correct reading with the power switch set to
“OFF” = ∞ Ohm
A correct reading with the power switch set to “ON”
= 4 to 5 Ohm
Fig 2
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