How to Test Power Tubes

Power tubes inside of amplifiers and other electronic equipment can be tested to see how much power is passing through the tube. Power tubes are generally found in older equipment, but many musicians like the sound of older amplifiers and must know how to service them to keep them in working order. Tube testers can be found in some pawn shops and on auction sites.

Things You'll Need

• Mutual conductance tube tester
• Rubber mat

Instructions

1. Remove the power tube from the amplifier and place the tube on a rubber mat.

2. Plug in the tube tester.

3. Connect the electrode leads to the ends of the power tube. Make sure to connect the positive and negative leads to the positive and negative ends of the power tube.

4. Turn on the tube tester and gradually increase the amount of power that is allowed to pass through the power tube. If the tube is able to still conduct power, it will register the flow of power through the tube on the meter of the tester.

5. Increase the power until it is set to the amount of power the tube is rated to conduct and check the meter reading. The meter should be reading an average load of power. If the meter is showing a low power read, the tube is bad.

References

• Rare Tubes: Tube Testing Methods
• South Valley: Tubes Q&A
• The Idiot's Guide to Tube Testers: Understanding & Using Your Tube Tester