Zoomlion ZT20J, Service And Maintenance Manual

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7-1
SECTION 7 ELECTRICAL INFORMATION AND
SCHEMATIC
7.1 General Introduction
This section introduces basic electrical information and schematics for locating and correcting most
operational problems that may arise. If problems that are not listed in this section, or problems that cannot
be corrected by the listed solutions, occur, you should obtain authoritative technical guidance before
performing maintenance.
7.2 Multimeter Basic Operation
Various types of multimeters or Voltmeters (VOM) can be used for troubleshooting. This section lists the
schematics of commonly used digital voltmeters in several different circuit measurements. Some of the
content may not match your Volt table.
Please refer to the Voltmeter User Manual for details.
7.2.1 Grounding
Multimeter Grounding means connecting the black lead (connected to the COM, common pole, or
negative terminal) to the negative side of the power supply with an appropriate path.
7.2.2 Backside detection
Backside Detection refers to the measurement by connecting the connector contacts on the same side of
the wire, ie the rear end of the connector.In this way, the circuit is turned on to obtain a reading. If the
connector is sealed, backside detection should be conducted carefully to avoid damaging the sealing
material around the wire. It is best to use probes designed specifically for this technology, especially when
operating on sealed connectors. Insert the detector into the side of the connector as much as possible to
ensure that the test can detect both ends of the connection. The connection inside the closed connector
can be detected by back detecting both sides of the connector terminal and measuring the resistance. Prior
to this, the wire should be gently pulled to verify that the wire is still connected to the contacts and that
the contacts are sealed in the connector.
7.2.3 Minimum value/maximum value
Intermittent load conditions can be measured separately using the Min/Max recording function of some
multimeters. For example, if a certain electromagnetic coil is energized only when the switch is kept away
from the coil and the multimeter, the voltage of the electromagnetic coil can be read by this function.
7.2.4 Polarity
The predicted voltage is positive and the actual voltage or current reading is negative, indicating that the