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INSTALLING NEW TUBES
First, see the SAFETY NOTICE earlier in the manual.
Output tubes are type KT88. Replacement output tubes should be purchased from VAC. It is desirable that tubes
be in matched octets, and be close to the "bogey" values for the major parameters. Make certain that each tube
fits firmly in its socket.
ALL POWER MUST BE OFF. Remove the top grill and the old tubes after they have cooled down (TUBES BECOME
HOT ENOUGH TO CAUSE SERIOUS BURNS WHEN IN OPERATION AND MAY TAKE SEVERAL MINUTES TO COOL
DOWN). Install the new tubes firmly and fully in the sockets, observing that the tube will only fit into the socket
in one orientation, determined by the plastic "keyway" in the center of the base. Do not use excessive force.
Replace the top rods before operating the amplifier.
The patented VAC iQ system will adjust the bias settings for the tubes automatically. The front panel indicators
will let you know if there is a problem with any of the KT88 tubes.
A slight violet glow in the tube is not cause for concern.
The small tubes are type 6SN7GTB. They should be matched section-to-section and to each other, and be close
to "bogey" values - this is particularly important for the VAC direct-coupled circuits.
In the event that trouble is encountered check connections and/or try another tube. Stop if the problem persists
and consult with your dealer or VAC.
For further information, refer to Tips & Advice: Tubes in General and Tips & Advice: Output Tubes.
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