2. Over Voltage fault: An over voltage fault indicates a permanent fault condition for which the
amplifier has to be shut down to protect itself. In this condition the front panel red POWER light is
flashing and the display indicates a flashing ----, indicating that the amplifier cannot be re-powered,
and must be referred to a technician for service before re-power is allowed. If AC power is lost the
fault condition is retained in memory and the red POWER light will be turned on whenever AC
power is re-applied.
Non-AC Power supply fault shutdown, unit in standby mode
Tube Service Reminder
Tube condition dramatically affects performance, and is determined by testing and/or listening. Weak tubes
sound tired and don’t have the snap and punch they had when they were new. Every 3000 hours of TUBE
TIME will display the green tube fault light with the number of hours in TUBE TIME on the front display.
This number is a median expected tube life, and can vary by user. In some cases tubes will last less than this
time, and in some cases longer, depending upon power levels that the amplifier is operated at. The service
reminder is used to remind the user to check the condition of the output tubes with a quantitative test, and
then replace any faulty, gassy or weak tubes.
We recommend that the tubes be replaced when the reminder is displayed and then the service indicator can
be re-set, and it will reappear after the next 3000 hours to remind the user to do the tube check tests again.
Reset / Clearing faults
Fuse Tester
This amplifier is equipped with a fuse tester in the lower right corner of the Fuse/AC rear panel. There are two fuse
holders, one larger and one smaller, and a switch labeled FUSE TEST. The Fuse test system and the two fuse holders
are not part of the amplifier’s protection circuitry, but are just connected to a low voltage sufficient to turn on the light
if the fuse in either holder is good, and spare fuses may be kept in either holder.
To test either type of fuse, insert the fuse into the appropriate fuse holder, and press the momentary
Fuse Test
switch
down. If the fuse is good the LED will light when the switch is depressed, and if the fuse is blown the LED will not
light, to indicate a fuse that needs replacement.
S-400 Amplifier Owner’s Manual
VTL
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