Doosan 25/300, Electronic Service Manual

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Book No. 22772784 (9--8--06)
HP1300/1600WCU Electrical Manual
MEASURING VOLTAGE, RESISTANCE,
FREQUENCY AND DUTY CYCLE
General Measuring Guidlines:
Since the electrical system uses sealed connectors and splices, access of test points can be difficult. It is rec-
ommended that a test probe kit be used to access the signals to prevent damage to wires and connectors.
Back probing connectors and insulation piercing test probes can cause damage that can cause future failures.
Measuring Voltage:
A digital voltmeter is recommended to make measurements. Voltage measurements are made by connecting
the RED + lead to the desired signal and the BLACK lead to the common. The test lead connections must be
secure or incorrect readings will result. Use circuit common for the Black lead, not chassis ground or other
metal connection. Circuit common will be any of the BROWN wires or battery negative can be used.
IMPORTANT INFORMATION
DO NOT USE MACHINE FRAME, SHEET METAL, PIPING OR OTHER METAL COM-
PONENTS AS COMMON OR GROUND WHEN MAKING VOLTAGE OR FREQUENCY
MEASUREMENTS.
Measuring Resistance:
Extra care must be taken when making resistance measurements. Test probe connections are crucial to cor-
rect readings. Ensure the test probe makes a solid connection with the wire(s) or connector pin(s) under test.
the test probe kit may help with these types of measurements. Make sure system power is turned OFF while
making resistance measurements.
Measuring Frequency:
Frequency is measured in the same manner as voltage, but the meter is set for “HZ” or frequency. Good con-
nections are important or false readings will occur.
Measuring Duty Cycle:
To measure duty cycle, setup the meter as if measuring frequency or voltage. Select the “%” or duty cycle
function and take the measurements. As of the date of this writing, Fluke is the only known digital voltmeter
that has the duty cycle feature. The Fluke Model 87 Digital Meter has the duty cycle function.