9
INSTALLATION & OPERATION
the connection between the MOD V and a THX monitor.
The cable should have a male DB25 on one end, and female
on the other end. You must use a cable in which all pins of
the DB25 are connected. Some computer cables do not con-
nect all pins. The middle DB 25 connector provides inputs
for 70mm magnetic signals from external preamps. The far
right DB25 connector is an alternative input connection for
a digital decoder (i.e. DTS, Dolby Digital).
See below for
specific pinout configuration.
The MONITOR DB25 outputs:
Pin 2
Left
Pin 16
Left Extra
Pin 5
Center
Pin 8
Right
Pin 19
Right Extra
Pin 23
Left Surr.
Pin 24
Right Surr.
Pin 25
Sub+
Pin 12
Sub -
Pins 3, 10, 11, 14, 17 & 20 Ground
The MAGNETIC DB25 inputs:
Pin 1
Left
Pin 2
Center
Pin 3
Right
Pin 4
Surround
Pin 5
Left Extra
Pin 6
Right Extra
Pins14-20
Ground
The DIGITAL DB25 inputs
Pin 1
Left
Pin 3
Center
Pin 5
Right
Pin 6
Left Surr.
Pin 7
Right Surr.
Pin 8
Sub
Pin 12
Digital
Pin 13
Stereo A / Stereo SR *
Pin 14
Ground
*see Default Optical Selection below
DEFAULT OPTICAL SELECTION:
External Digital Decoders available on the market (i.e.
DTS) have a function that instructs the processor to switch
to an optical format in the event that the digital decoder fails
or loses time code. When this happens, the digital decoder
will pulse a special terminal to ground to alert the processor
to switch to the optical format.
On the MOD V Digital DB25 input connector, this terminal
is the Stereo A / Stereo SR pin (see above). The MOD V
will switch to either Stereo A or Stereo SR depending on
the location of a 0 ohm resistor jumper located on the lower
right side of the back motherboard.
The MOD V is shipped to default to Stereo A in the event
of a digital decoder problem. In this default mode, J1 has a
0 ohm resistor installed and J 2 does not. For a default set-
ting of Stereo SR, you must remove the 0 ohm resistor
jumper on J1 (it must be desoldered) and one must be
installed on J2 (soldered in place). The factory default set-
ting of Stereo A should be adequate for most theatres.
However, if a Stereo SR default is desired, then all plug-in
cards must be removed along with the internal tray in order
to access the back motherboard. Use extreme care when
removing and plugging in the circuit cards. Make sure
power is removed from the system before doing so.
MUTING FUNCTION:
A convenient mute terminal on the back of the MOD V
allows all output channels of the MOD V to be silenced
whenever this terminal is grounded.
Note: On earlier units, the MUTE terminal was mistakenly
marked as GROUND. This terminal is the sixth one from
the left on the far left entrelec connector as viewed from the
rear of the MOD V.
REMOTE FADER OPERATION:
The volume control of the MOD V can be operated remote-
ly at another location, independent of the MASTER FILM
FADER. This can be accomplished by adding a remote, lin-
ear taper 10k ohm pot (to act as a volume control) between
the REM SEND and GROUND terminals on the back of the
MOD V. Connect the wiper of the remote pot to the REM
RETURN terminal. (See diagram.)
The toggle switch on the left hand side of the front panel
display board, labeled VOLUME SELECT, allows the oper-
ator to select either local or remote volume control of the
MOD V. This switch is easily accessible by opening the
hinged front panel.
Note: Remote operation is for film formats only, and will
not affect the music level.
GROUNDING
On the left rear side of the MOD V (see below), next to the
power supply terminals, a special ground wire has been
added to allow jumpering of the MOD V circuit ground to
the system chassis ground. Normally, this wire is left
unconnected which separates circuit ground from chassis
ground. In most cases, this will result in the least amount of
ground loop problems.
In the event of ground problems, this wire may be connect-
ed to any terminal marked GROUND on the rear of the
MOD V. This will then jumper the circuit ground to chassis
ground. Take special caution when diagnosing ground prob-
lems; what may work with one sound system may not nec-
essarily work with another.
Rear view of MOD V showing the special ground wire.
