Revision B • 7/00
H
A
R
R
I
S
C
O
R
P
O
R
A T
I
O
N
8
4 Equipment Description
The module holds the logic-state backup bat-
teries used in case of momentary power outage.
Two AA batteries ensure the console powers back
up in the same logic state when power fails mo-
mentarily.
The faceplate timer control switches (Start, Stop,
Reset, Hold) manually control the timer section
of the clock/timer assembly. The Auto button con-
trols whether the timer reset bus logic is connected
to the timer. When Auto is active (button lit) the
timer automatically resets at module On for any
module with the Timer Reset logic function turned
on (Logic Settings switches 5 or 6 set to the
operator’s left).
CLOCK/TIMER ASSEMBLY
For this section refer to the clock/timer sche-
matic page in Chapter 6.
The clock/timer consists of a clock/timer dis-
play and a main clock/timer circuit board. A rib-
bon cable connects the display board to the main
clock/timer circuit board.
The display board has the eleven 7-segment dis-
plays for the clock and timer and three Hall-effect
switches. The Hall-effect switches are used for set-
ting the time when the clock is run in manual
mode.
The clock/timer is built around a microcontrol-
ler IC (U1). The microcontroller handles both the
timer and clock display functions. For a 12-hour
clock display a PR&E # 21-122-1 microcontrol-
ler is used (standard with the AirWave Digital).
For a 24-hour clock display a PR&E # 21-122-2
microcontroller can be substituted.
The +12 volt supply, from the timer control mod-
ule, is regulated on-board to generate the +5 volt
and +8 volt supplies. The +8 volts is used exclu-
sively by the clock oscillator circuit.
The clock oscillator (U2, Q21, U10) controls the
clock timing when the Master/Slave switch (S1,
#1) is in Master mode. In Slave mode, the clock
timing signal comes from an ESE TC76 or TC89
time code signal input on BNC connector J3. The
time code signal is buffered (U9, Q23, U3) and
applied to the microcontroller. If ESE time code is
lost, the microcontroller will revert to using the
internal oscillator as the timekeeping reference
(flashing LED CR3 to indicate time code loss).
The timer can be controlled through the
console’s timer reset bus (when the Auto function
is active) and manually through the timer control
module buttons.
S1, #2 controls whether the tenths of seconds
display is turned on while the timer is running.
The tenths of seconds are always displayed when
the timer is stopped.
BARGRAPH METERS
The two sets of meters are mounted on a single
board in the meter panel. The meter input (J1)
comes from the right-hand motherboard connec-
tor J2. Refer to the two page meter schematic (92-
1011) in Chapter 6.
Each of the four meters (Pgm-1 Left, Pgm-1
Right, Pgm-2/Pgm-3 Left and Right) is made up
of three 10-segment LEDs (D1 - D4, D7 - D14)
with a dual LED (D5, D6) Full Scale Peak Indica-
tor. Two 8-input NPN drivers (U3 and U4) sup-
ply anode current, while two 4-input NPN driv-
ers supply cathode current sinking. The drivers
are controlled directly by the programmable mi-
croprocessor (U1).
U8, a 555 oscillator, supplies an 80% duty cycle
2 kHz multiplexing signal to the microprocessor.
This signal also is used to set the LED brightness.
Both meters can be set to display Volume Units
(VU) or Peak Program (PPM). The type of dis-
play is set by an internal DIP switch on the Out-
put module. This controls the logic level of the
DISPLAY VU/~PPM line which, through NOR
gate U2, either lights the PPM or VU LEDs in the
two meters through drivers Q1 or Q2. Likewise,
