The Screen fuse is rated at ¾ A fast acting 600V fuse. The Plate Power supply fuse is rated at 2.5A. fast
acting 600V fuse. There is also one Logic AC fuse rated at 1.0A Slo Blo (100/120Volt, 220/240V AC). The
B+ AC is rated at 20A Slo Blo (100/120Volt AC) or 10A Slo Blo (220/240 Volt AC) ceramic. The input
and filament AC fuses are rated at 2A Slo Blo (100/120Volt AC) or 1A Slo Blo (220/240 Volt AC) ceramic.
There is also a non-user serviceable Raw B+ fuse housed in a PC board mounted fuse holders located inside
the audio unit. This fuse is to be service only by an authorized service Technician.
To change the AC fuse first ensure that the unit is powered off, and disconnect the AC power cord from the
unit. Move the amplifier so that you can work with the panel in the back of the amplifier chassis.
The type of fitting used for the fuses is called a bayonet fit, which describes the action needed to remove the
fuse cap. Locate the Main fuse holder, and loosen it by inserting a flat head screwdriver into the slot and
turning the screw head approximately one quarter of a turn in a counter-clockwise direction while pressing
inwards. The fuse cap should spring out from its housing with the fuse held inside the cap. Take the fuse out
and replace it with a new one, and insert the fuse cap back into the holder, pushing it downward while
turning it in the clockwise direction to lock it in place. Use the same procedure to replace the output stage
protection fuses.
WARNING: For continued protections against fire hazard only replace the
fuse with the same type and rating as was specified for the amplifier by
the VTL factory. If you have problems locating the correct fuse contact
your VTL dealer or the VTL factory service department.
WARNING: Before powering on the amplifier after a fuse change, it is
extremely important to find the problem that caused the fuse to blow
in the first place. Consult your dealer or the VTL factory and inform
them of the fuse problem.
Cleaning
Your VTL amplifier can be dusted occasionally with a damp non-abrasive cloth. You should not use any solvents
for cleaning the front panel, as this can damage the lettering and the finish.
Troubleshooting
1.
When I power on the amplifier from the rear rocker switch, nothing happens. What should I do?
Check to make sure that the power cord is properly connected to the amplifier’s Power AC inlet as well
as the AC outlet from the wall. If there is no problem with the power source, check the fuse unit in the
back panel of the amplifier with the Fuse Tester in the back of the amplifier. (See the section on
Advanced Functions and Diagnostics in Chapter 3 for details on how to test the fuse using the Fuse
Tester.) If the fuse is blown, replace it with a new fuse, and try turning the power on the amplifier
again. If the problem still persists, contact your authorized VTL dealer or the VTL factory immediately.
S-400 Amplifier Owner’s Manual
VTL
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