The MB-125 Front Panel
The MB-125 Front Panel showing the Power on switch and the power on LED indicator.
Check for tube placement
Use the following procedures to check whether the tubes standing on the deck of your amplifier are placed
firmly in their sockets, as the tubes can become dislodged and loosen during shipping of the amplifier.
Visually inspect through the vent holes to ensure that all tubes are fully seated before powering the unit on for
the first time. If there are any tubes not fully seated then you should refer to your VTL dealer, and take this
procedure with the amplifier.
Notes for the servicing technician:
1.
Remove the protective wire cage on the top deck of the amplifier. The cage is mounted with
three screws on each side of the amplifier. Loosen the screws and lift the wire cage slowly and
carefully. Do not let the cage touch or hit any of the tubes inside the amplifier. Keep the cage
and the screws in a separate place while you’re working on the amplifier.
2.
Make sure that the amplifier is not connected to the power outlet and not turned on. Use your
fingers to hold onto the upper portion of the tube towards its tip. Gently rock the side of the
tube to see if there is any movement in the tube. If there is any movement, that means the tube
has come loose. Press the tube firmly into its socket, using a gentle force and a slight “rocking”
motion.
3.
Repeat the above test for the rest of the tubes. There are a total of four output tubes and two
input tubes in each amplifier.
MB-125 Owner’s Manual
VTL
4
