Specifications
"Monitor" gain control can then be used to adjust
the level of this signal which appears across the
front panel monitor speaker, the front panel Head-
phone jack, and the rear panel speaker jack.
When one or more M675 lnput controls are turned to
"Cue" (fully counter-clockwise), the program feed to
the monitor amplifier is attenuated by 19 to 31 dB.
The Cue material is then routed to the monitor
amplifier, overriding the program material. When all
lnput controls are returned to normal (not in cue),
program feed is again applied at normal level to the
monitor amplifier. This provision allows monitoring
of program material at a low level while simultane-
ously cuing.
Talkback Operation:
To hear talkback material originating at the opposite
end of a two-way line connected to the M67 line
output, turn all input pots on the M675 out of cue
and turn up the monitor amp volume control. The
M67 master volume control may be turned down if
necessary.
DC Power
The M675 can be powered in two ways: by an ex-
ternal source or by internal batteries. When 30 Vdc
is applied to the "30 VDC" connectors of the
M675,
the M675 will be turned on. The power "On-Off"
switch on the front panel controls only its own
internal battery supply. Thus, if the M675 is to be
powered by an external source such as an M67,
M63 or
SE30, the power switch on the M675 need
not be on. Note that if the M675 internal battery
supply is used to power an accessory such as the
A68M Microphone Preamplifier, the power switch
will control power to the accessory.
The M675 internal battery supply can be used to
provide automatic switchover to battery operation
when used with the M67. When the M675 batteries
are installed and the M675 is connected to an
ac-operated M67, automatic power switchover will
take
place if the ac line voltage fails, as long as
the M675 power switch is in the "On" position. The
M675 batteries will then power both the M675 and
the M67. Note that automatic power switchover is
not advisable with the M63, because some battery
drain will occur even when the M63 is operating on
an acceptable ac line voltage, due to the character-
istics of the M63 power supply. Automatic power
switchover is possible with the
SE30, although the
SE30 has its own built-in battery supply for this
purpose.
Batteries (not included):
The M675 contains a battery supply requiring six
9V transistor radio batteries (Burgess 2U6, Eveready
#216 or equivalent are recommended). Access to
the steel, leak-resistant battery compartment is on
the bottom panel of the
M675. To remove the battery
compartment, each of the two locking screws should
be given a
'/4
turn CCW. The battery assembly may
then be removed. The six
9V batteries are snapped
into position on the printed circuit board contained
in the compartment cover. The entire compartment is
removable from the M675 by disconnecting the snap
connector (attached to the leads leaving the cover)
from the M675 receptacle. When the M675 is stacked
with an M67 Mixer, the M675 should be below the
M67 to retain access to this compartment.
Battery Check:
The nominal voltage available from the complement
of six
9V batteries is 27.0 volts. Initially, new bat-
teries may provide a supply voltage of up to 30.5
volts. Minimum acceptable battery voltage is con-
sidered to be 21.5 volts.
The battery-check function of the M67 may be used
to indicate battery condition when the M67 and
M675 are used together.
"0" on the M67 VU meter
indicates a marginal battery condition.
For best performance on battery operation at
temperatures below
40°F, change batteries when the
Battery Check meter reading is
+
1.0 VU or lower.
This is due to the operating characteristics of carbon
zinc batteries at low temperatures.
NOTE: For improved performance and longer op-
eration at low temperatures
(O0C-32"F-
or lower), use manganese-alkaline batteries
(Mallory MN-1604 or equivalent).
RF
Susceptibility:
When using M675-M67 combination in a high RF
location, RF pickup may occur due to the ground-
ing system of the Mix Bus on early
M67s. If this
difficulty should occur, it may be easily remedied by
Current Drain and Battery Life:
Approximate Approximate
Condition Current Drain Battery Life
M675 only, "Phono-Line" in "Line," monitor level down
1
mA over 300 hrs
M675 only, "Phono-Line" in
"Phono," monitor level down
4
mA 170 hrs
M675
+
M67, "Phono-Line" in "Line," M67
@
+4 dBM
5 mA 140 hrs
M675
+
M67, "Phono-Line" in "Phono," M67
@
+4 dBM
8
mA 85 hrs
M675
+
M67, "Phono-Line" in "Line," M67
@
4-4 dBM,
M675 monitor speaker at 10 mW 7 mA 100 hrs
M675
+
M67, "Phono-Line" in "Phono," M67
@
+4 dBM,
M675 monitor speaker at
10
mW 10
mA
65
hrs
NOTE: Due to operating characteristics of carbon-zinc batteries at low temperatures, the useful operating
life will be noticeably shorter at lower than normal room temperatures. See Battery Check Instructions.