VAC Standard 220 - Manual (Page 8)

Page 8
VAC will be happy to test tubes for concerned
customers.
Installing New Tubes:
Original Equipment Replacement tubes are
available from VAC. These tubes ensure your
Standard 220 will meet or exceed all factory
performance specifications.
Before replacing tubes, all power must be off.
Mute unit, place power switch in the “off”
position and unplug power cord. Remove cover
and old tubes ONLY after the unit has cooled
down (In normal use, tubes become hot enough to
cause serious burns. Allow several minutes for
tubes to cool before attempting to remove or
replace.) Install the new tubes fully firmly in their
sockets, taking care to observe the direction of the
locating ridge in the plastic center pin of the
KT88 output tubes’ metal & phenolic base. With
9-pin miniature tubes, make sure that pin pattern
corresponds to holes in tube socket.
When changing KT88 tubes, turn the bias control
corresponding to the new tube fully
counterclockwise. After turning the unit on and allowing it to reach normal operating temperature,
follow the normal biasing procedure.
In the event that trouble is encountered, switch power to the “off” position, check that all tubes are
correctly seated in their sockets and check all signal, speaker and power connections. If possible, try
another tube. If the problem persists, please consult your VAC dealer or contact the factory directly.