There is also a non-user serviceable Raw B+ fuse housed in a PC board mounted fuse holders located inside
the amplifier. This fuse is to be serviced only by an authorized service Technician.
To test whether a fuse is opened or not, place the two probes from a Multimeter on the two metal ends
of the fuse. Turn the Multimeter to the Ohm setting or the milliOhm setting. The milliohm setting in
many meters can be used for continuity test as well and the meter will beep when the fuse has good
continuity. When the fuse is in working condition, the meter will indicate a small resistance readings
on the ohm setting. If the reading is zero or the meter doesn't beep, then the fuse is likely to be
opened.
To change the either the Screen or Plate fuse or any of the AC fuses 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 AC 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 should 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. It is recommended that you use a contact cleaner
such as Pro-Gold on the input and output connectors regularly to ensure optimum sound and proper signal conducting
capability.
Transporting MB-450
If you should ever need to ship your amplifier and need help doing so, ask your VTL authorized dealer to give you assistance
in packing the unit into the carton for the amplifier. Your dealer should also be able to arrange for new cartons to be sent to
you and help you with the packing should you require it. Always ship the amplifier with the original carton and foam
supplied by VTL. We recommend that you ship the amplifiers on a pallet to avoid shipping damages as they are very heavy
and not suitable for ground shipping.
MB-450 Series III Signature Monoblock Owner’s Manual
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