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Basic Mode of Operation  

This power supply is designed to operate as either a constant voltage or constant current source. Automatic crossover to either mode of 
operation occurs when the load condition changes.  The power supply functions as a constant voltage source (

CV

) as long as the load 

current is less than the preset current limit value. When load current is equal to or greater than the preset current limit, the power supply will 
automatically cross over to constant current 

(CC)

 mode. The voltage will drop, 

(CC)

 will show on the LCD display panel and the power 

supply will operate as a constant current source. When the load current drops below the preset current limit, the supply will return to 
constant voltage (

CV

) mode. 

  

Operation  

 

Make certain the AC power cord is connected to a proper power source.  

 

Make certain that no load is connected to the supply. 

 

Switch on master ON/OFF 

POWER

 switch (1) on the rear panel, the LCD display backlight should illuminate.  

 

The (

CV

) icon should be shown on the display and the 

OUTPUT

 (6) should default to 

OFF

 

If current limiting is not required, turn the 

CURR

 (5) control fully clockwise.  

 

If current limiting is required, see the steps in the following section “Presetting a Current Limit Value”. 

 

Press the 

OUTPUT

 (6) button to activate the power supply output. 

 

Set your desired output voltage, and then press 

OUTPUT

 (6) again to deactivate the output. 

 

Observing correct polarity, connect to your load to the power supply.  

 

Press the 

OUTPUT

 (6) button to activate the power supply output. 

 

Check the power supply display to verify that the (

CV

) icon is displayed. If (

CC

) is displayed, your current limit value is too low, 

the load requires more current than the supply is capable, or there is a fault in the connected device.  

 

Presetting a Current Limit Value (CC)  

In many cases, it becomes necessary to preset the current limit prior to having the load connected to the supply. To accomplish this, the 
following steps should be followed. 

 

With no load connected to the supply, switch on the power. 

 

Press the 

OUTPUT

 (6) button to the 

ON

 position to activate the supply output. 

 

Adjust the 

VOLT

 (4) control to approximately 3VDC output. 

 

Press the 

OUTPUT

 (6) button again to deactivate the supply output. 

 

Turn the

 CURR

 (5) control fully counterclockwise. 

 

Short 

OUTPUT

 terminals (7) and (9) together  

 

Press the 

OUTPUT

 (6) button to the ON position to activate the supply output. 

 

Adjust the 

CURR

 (5) control clockwise until the desired current limit is displayed. 

 

Press the 

OUTPUT

 (6) button again to deactivate the supply output and remove the short between terminals (7) and (9). 

 

The supply is now set for this current limit throughout its voltage range. 

 

Protection 

To provide protection to the power supply and the connected load, the supply incorporates over voltage (OVP) thermal protection. 
Traditional power supplies often provide over current protection, however that benefit already exists by sheer design of a current limiting 
supply. 
 

Over Voltage Protection ( OVP )  

In the event that the output voltage control circuit mal-functions, the maximum output voltage will not exceed 30% of the adjusted 
voltage value at the time of the operation.  

 
Over Temperature Protection  

If the temperature inside the supply exceeds a pre–determined value, the output voltage and current of the supply will decrease to 
zero to prevent damage to the supply. When the temperature inside supply returns to approximately 65°C (150°F), the power 
supply will automatically return to operation.  

 
 
 
 
 

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Summary of Contents for 72-8340

Page 1: ...y Series Instruction Manual Model 72 8340 1 0 60VDC 0 1 6A 72 8345 1 0 36VDC 0 3A 72 8350 1 0 20VDC 0 5A Copyright 2008 all rights reserved Tenma Test Equipment www tenma com Downloaded from Elcodis com electronic components distributor ...

Page 2: ...ment in direct sunlight or near any heat source 4 Before plugging into AC power source check with the rating label at the back of the unit 5 Do not block ventilation openings on the unit 6 This unit must be used within the specified rating Continuous excessive loading may cause damage to the power supply 7 The AC power cord must be at least 18AWG and not exceed 3m in length 8 Replacement fuse T3AL...

Page 3: ...put black 10 LCD isplay Panel Backlit panel shows CC CV Mode Output status Voltage and Current output Operation Ground Connection Depending on the application the power supply output terminals can be grounded to suit any one of the following conditions Negative Ground Black negative terminal is tied to the green GND terminal Positive Ground Red positive terminal is tied to the green GND terminal F...

Page 4: ...s more current than the supply is capable or there is a fault in the connected device Presetting a Current Limit Value CC In many cases it becomes necessary to preset the current limit prior to having the load connected to the supply To accomplish this the following steps should be followed With no load connected to the supply switch on the power Press the OUTPUT 6 button to the ON position to act...

Page 5: ...witching Operation Frequency 80KHz 120KHz Power Factor 0 68 Efficiency at Maximum Power 84 85 85 Voltmeter Display 4 Digit Ammeter Display 4 Digit Voltmeter Accuracy 1 5 counts 5V 1 5 counts 10V 1 5counts 20V 1 3counts 5V 1 3counts 10V 1 3counts 20V Ammeter Accuracy 1 5 counts 2A 1 5 counts 1A 1 5 counts 0 5A 1 3 counts 2A 1 3 counts 1A 1 3 counts 0 5A LCD Indication CC CV Amp Volt Output ON OFF P...

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