Studio Technologies IFB Plus 2001 - Manual (Page 25)

Model 2 User Guide Issue 7, November 2001
Studio Technologies, Inc. Page 25
of the circuit board. Ensure that the ends
of the straps do not extend below the
circuit board so as to touch, or even come
near the bottom of the chassis. Failure to
heed this warning can result in safety,
reliability, and operational problems.
Confirm that the required straps have
been installed for all three transformers.
5) If the mains voltage was changed,
replace the fuse with the correct value:
0.5A for 120V, 0.25A for 220/240V. The
fuse is a 5 x 20mm fast-acting type.
6) Replace the top cover and secure it
using the screws.
7) Before reconnecting mains power, use
an ohm meter to ensure that none of the
straps leads have shorted to metal chassis
below the circuit board.
8) Reconnect the mains power and check
the Model 2 for correct operation.
Dim/Mute Function
From the factory, program audio is set to
mute upon interrupt. If level “dimming”
rather than full muting is desired, a simple
modification can be performed by a quali-
fied technician.
The following procedures must
be performed by a qualified
technician. Operating the Model
2 with the cover removed exposes the
technician to points in the power input
section with hazardous voltages.
1) Ensure that the mains power cord
is removed from the Model 2’s power
connector on the back panel.
2) Remove the top cover via the four 6-32
button head cap screws.
3) Referring to page 2 of the Model 2’s
schematic diagram, find the resistor
identification numbers for the dim resis-
tors. From the factory, resistors are not
inserted into these locations. If resistors
are installed, someone has beaten you
to the punch and already performed this
modification!
4) Refer to the chart located in the lower
left corner of page 2 of the schematic. The
chart gives resistor values corresponding
to several “dim” values. The level in dB
refers to the program level drop that will
occur during an interrupt. After selecting
and acquiring the desired resistors, pre-
pare them for insertion into the circuit
board. With care, the resistors can be
added without removing the circuit board
from the chassis. Bend the leads so that
they are ½-inches apart, allowing them to
easily drop into the resistor locations. Trim
the leads so that once inserted and sol-
dered into the board, the ends of the leads
will not touch the chassis below the board.
Again, ensure that the ends of the straps
do not extend below the circuit board so
as to touch, or even come near the bottom
of the chassis. Failure to heed this warn-
ing can result in operational problems.
5) Replace the top cover and secure it
using the screws.
6) Reconnect the mains power and check
the Model 2 for correct operation.
Alternate Program Audio Routing
Refer to the Model 2 block diagram,
located at the end of this guide, when
reading this section. The default audio
routing of the program audio signal is to
join interrupt audio after the compressor/
limiter. This means that the original
dynamic range of the program audio