How to Replace a Tube in an Amplifier

Replacing vacuum tubes in an amplifier is a relatively easy task. Although a mystique has grown about tubes in recent years, they used to be common items found in drugstores and corner shops. People viewed replacing vacuum tubes in much the same way today's society views replacing batteries. Replacing vacuum tubes at home is considerably cheaper than taking an amplifier to a technician. Read on to learn how to replace a tube in an amplifier.

Instructions

Difficulty: Moderately Challenging

Things You’ll Need:

• Screwdriver
• Replacement Tubes
• Gloves (optional)

1. Unplug the unit and remove the access panel to expose the vacuum tubes. If the unit has been in use, allow it to cool thoroughly.
2. Removing the chassis is a job for a qualified professional technician because the unit may retain a considerable amount of electricity in the capacitors even when unplugged. If the chassis must be removed to change tubes, replace the access panel and take the unit to a professional technician. Remove any tube covers on bad tubes.
3. Remove the bad tube(s). Only pre-amp tubes may be replaced as singles. If a power tube is bad, replace the entire set of them with another set. Replacing power tubes may require biasing the unit. You may need to consult the owner's manual.
4. Replace all bad tubes with good vacuum tubes of the same design. Make sure that each tube is pressed firmly into its socket.
5. Turn the unit power on, but not standby if the amplifier is equipped with a standby switch. Allow unit to warm up for approximately ten minutes and check each tube for the glowing heater filaments. If the replaced tube is not glowing, the problem may be internal and require a professional technician to service it. Turn on standby switch if necessary.
6. Adjust unit to a maximum one-tenth of total volume, and insert a signal. Operate amplifier for 30 to 60 minutes at this low volume to allow the new tubes to adjust to the unit. If there is a further problem, it should become apparent during this period.
7. Replace access panel.

Tips & Warnings

• Unplug unit and do not touch metal chassis while replacing tubes.
• Be aware that the tubes get very hot.

Who Can Help:

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