Power supplies can be tested by placing a "load resistor" in circuit between the red and black electrodes, and then, with an ammeter or a voltmeter, the current or voltage can be tested to see if the power supply output is within specifications. The testing meter is also called DVM (digital volt meter) or multi-tester. Both a DVM and a multi-tester can measure voltage, current, and resistance.

Here are quick procedures to determine if any of our power supplies are generating output and displaying what they should, based on the given load.

NOTE: In no way do these procedures test for all the possible power ranges. The tests can be used to identify if there is a hardware failure in most cases.

For a Model 1000/500 power supply or a PowerPac 1000 power supply, put a 2.5 kOhm/50 W resistor in between the electrodes and turn on the power supply to 350 V constant volts. Let it run for about 5 minutes (at which time the voltage stabilizes -- don't go by the display). Then take a reading with a voltmeter across the resistor. The voltmeter should read around 350 V and about 140 mA, ballpark. If it's far off of that reading, it should be sent in for repair.

For a Model 200/2.0 or PowerPac 200 power supply, use a 60 Ohm/100 W resistor and set the power supply at 100 V constant. Wait 5 minutes. The voltmeter should read around 100 V/1.65 A, and the power supply should have the same reading.

For a Model 3000/300, a Model 3000xi, or a PowerPac 3000 power supply, use a 2.5 kOhm resistor and set the power supply at 1000 V constant. Wait 5 minutes. Both voltmeter and power supply should read about 1000 V/390 mA/390 W.

For a PowerPac 300 power supply, use a 2.5 kOhm resistor, set the power supply at 300 V, and wait 5 minutes. The multi-tester and power supply should be around 300 V/116-118 mA.

If you have additional questions, either contact your local Bio-Rad customer service office or take advantage of Consult Bio-Rad, our online technical support service. You will receive an initial response to your question ("case") within one business day. Either log in or register for this service by clicking on the appropriate link. Then click on "Create Case" to describe your problem in detail. Be sure to include the part number (catalog number) of the power supply, and the purchase order number (P.O.) if it is under warranty.