ATX Computer

Power Supply Tester

Overview

The Tenma Model 72-1084 ATX Power Supply Tester is designed to provide fast convenient verification of proper operation of ATX style computer power supplies. Connecting an ATX 20-pin connector to CON1 of this tester will provide immediate visual indication of operation of the power supply. This tester also includes an analog voltage meter to verify correct voltage of the +3.3V, +5V, and +12V pins on this connector. Three separate connectors also allow verification of proper output voltage on the peripheral power, floppy drive power and +12V CPU power connectors.

Operation

Typically, ATX style power supplies are switched on/off from the motherboard. The Tenma ATX Power Supply Tester simulates this command by placing a proper current load across Pin4 and Pin5 of the 20-pin ATX connector. When its rocker switch is placed in the ON position, the power supplies cooling fan will engage, and the LED indicator, located in the tester rocker switch, will light. This indicates that the power supply is functioning. In most cases, this level of pass/fail testing is all that is required.

In some circumstances where the supply is operational yet erratic behavior exists, it may be desirable to verify correct voltage of the 3.3V, 5V and 12V outputs. The three position rotary switch and DC voltmeter panel allow easy verification of these voltages. Additionally, the supply voltage to external peripherals such as DVD/CD ROM, floppy and hard drives may be tested. This tester will verify these types of outputs on older type power supplies also.

Many low cost computer power supplies have one internal circuit for each of 3.3V, 5V and 12V voltages. In this case, all outputs whether on the motherboard, the processor or a peripheral connector, of the same voltage, are internally tied together. In higher quality supplies, these outputs are independent and isolated from each other. The Tenma #72-1084 ATX Power Supply Tester will independently verify each of these outputs, including the both +12V outputs on the P4 processor connector.

Directions

General Pass/Fail Test

  • Disconnect the computer power supply from the AC power source
  • Disconnect all IDE and other devices that are connected to the computer power supply
  • Disconnect the large 20-pin ATX connector from the motherboard
  • Set the rocker switch on the tester to the OFF position
  • Connect the 20-pin ATX connector, from the power supply, to the tester
  • Connect the computer power supply to an AC power source
  • Set the rocker switch on this tester to the ON position
  • If the LED on the rocker switch lights, the power supply is functioning

Testing Output Voltages

Caution

Simultaneously connecting to CON2, CON3 or CON4 could potentially damage the computer power supply

  • The 20-pin ATX connector must remain inserted in CON1 to allow the tester to keep the computer power supply in the ON mode
  • Ensure that the slide switch, located in the center of the unit, is set to the CON1 (left most) position
  • Use the three position rotary switch to individually test each of the +3V, +5V and +12V outputs on the ATX connector
  • The panel meter should show the same voltage reading on the meter
  • If the meter displays voltage other than that indicated by the switch, the supply is not functioning properly
  • Move the center slide switch to the CON2/3/4 (right most) position
  • Insert the small floppy drive connector (typically used for 3-1/2” drives) into CON2
  • Toggle the rotary switch between the 5V and 12V position to verify both supply voltages on this connector. This test should be performed independently for all connectors of this type
  • Remove the connector from CON2, and insert the peripheral connector in CON3
  • Toggle the rotary switch between the 5V and 12V position to verify both supply voltages on this connector. This test should be performed independently for all connectors of this type
  • If the rotary switch is set to the 3.3V position when testing CON2 and CON3, the voltage will still be measured from the ATX connector inserted into CON1
  • Remove the connector from CON3, and insert the CPU power connector into CON4

This connector provides two separate +12VDC supplies to the P4 processor on appropriate motherboards

The slide switch located just beneath the CON4 label allows these supplies to be independently tested

  • The only valid position of the rotary switch in this operation is 12V
  • Toggle the upper right slide switch between both positions to verify proper operation of these two supplies

Model #72-1082

Tenma Test Equipment

Test Specifications

This tester performs the following tests to the connectors shown below

CON1ATX Style Connector

Pin 2+3.3VDC

Pin 3Common (–) ground

Pin 4Resistive Load to Pin 5

Pin 5 Resistive Load to Pin 4

Pin 8LED Power Indicator

Pin 10+12VDC

Pin 14 Jumper to pin 15

Pin 15 Jumper to pin 14

Pin 17Led Power Indicator

Pin 20+5VDC

CON2Floppy Drive Connector

Pin 1+5VDC

Pin 2Common (–) ground

Pin 3Common (–) ground

Pin 4 +12VDC

CON3Peripheral Connector

Pin 1+12VDC

Pin 2Common (–) ground

Pin 3Common (–) ground

Pin 4 +5VDC

CON4P4 Type CPU Power Connector

Pin 1Common (–) ground

Pin 2Common (–) ground

Pin 3+12VDC

Pin 4 +12VDC

Model #72-1082

Tenma Test Equipment