Operation & maintenance, Important information – VAC Renaissance 70/70 User Manual
Page 2
Operation & Maintenance
IMPORTANT INFORMATION
PLEASE READ CAREFULLY
Your Renaissance Seventy/Seventy has been fitted with a thermal sensor circuit. It
works in conjunction with the indicator lights located under the VAC logo on the front
panel, and has two functions:
1)
If the idle current in a pair of 300B output tube should drop well below
acceptable limits, the light corresponding to that pair (left-most pair, left-center
pair, right-center pair, right-most pair) will light green. At least one of these
tubes should be replaced. Obtain a new tube, and replace one of the pair. If this
does not resolve the indication, return the original tube to its socket and replace
the other tube of the pair.
These lights will also be green when the amplifier is first switched on, and will
extinguish when the bias resistors have reached normal operating temperature
after several minutes. Note: a strong cool air current could cause the lights to
remain green even in normal operation.
2)
Should any output tube draw excessive idle current (run away or internal
short) the light corresponding to that pair will glow red and the high
voltage supply to that channel will be shut down. The red light will stay
on until the power switch is turned off. One tube of the pair must be
replaced. Obtain a new tube, and replace one of the pair. If this does not
resolve the indication, return the original tube to its socket and replace
the other of the pair.
The lights for the other three pairs will show green after a few minutes...this
should be disregarded.
This protection feature normally will operate with much greater speed than the
AC line fuse, and provides a high degree of protection against elevated
temperature or fire due to a major failure in an output tube. However,
completely failsafe methods are not possible. As with any high power electrical
device, never leave the amplifier run unattended. Turn the amplifier off
immediately if you smell any strong odor, or if you see any parts glowing orange
through the gold vent grille.