Honeywell
COMPONENT MAINTENANCE MANUAL
PART NUMBER 964-0452
1I.B.1516A Page 46
Mar 30/01
23-12-01
sues a fault message to Controller Voice, A8 via D2-A and D1A only after about
15ms. This delay is necessary in order to prevent the drop in the +28V supply
voltage in the event of a power failure during the 10ms transparency period be-
ing incorrectly interpreted as a power supply fault.
Comparator, N6-C, monitors the CPLPS supply voltage for the antenna coupler.
A voltage of about +2.5V is applied at N6-C by means of resistors, R40, R99,
and R67, the latter being responsible for the switching hysteresis.
If the voltage at N6.6 exceeds this value, which is the case with a voltage of
+11V at CPLPS owing to R73 and R83, N6-C switches its output to high resis-
tance, and signal CMVCPL is set to H Level via pull-up resistor, R58. This caus-
es a CMlNT pulse to be generated via D2-A, which prompts Controller Voice,
A8, to inquire the CM messages via the module data bus. Since the CPLPS volt-
age can be switched OFF via the data bus (CPLOFF = H), the monitor must not
interpret the absence of voltage as a fault in this case. For this purpose, the
CPLOFF signal is applied via diode, V74, at N6.6, and consequently, C87 is
quickly charged to more than +4V, Immediately, switch OFF begins, whereby
N6-C is retained at L level at the output. CPLOFF goes to L level in conjunction
with the starting command, and C87 maintains the voltage at N6.6 >2.5V until
CPLPS is increased to the nominal value; further discharge is prevented.
In order to be able to determine whether a failure in the CPLPS voltage is attrib-
utable to a defect in the Power Supply, or an external short circuit (and therefore
a fault in the Antenna Coupler), the output current at CPLPS is monitored, and
CMCCPL = H is signalled via the data bus if the maximum value is exceeded.
In this context, the voltage at R21 is tapped (CCPL+ and CCPL) as a measure-
ment for the current, and supplied to comparator, N6-8, which is configured sim-
ilarly to a differential amplifier. Resistors R39/R38 and R48/R69 divide the input
voltage to provide the value permitted for N6-B. R81 defines the response
threshold, and R62 defines the hysteresis of the comparator.
If the current is within the permitted range, N6-B is on H level,c C51 is main-
tained at +5V via R70, and gate D4-C sets CMCCPL to L level. If the response
threshold is exceeded, N6-6 switches to L, C51 is discharged via R88 and di-
ode, V63, with a time constant of 12ms. Together with C55, this leads to a re-
sponse delay time of about 15ms. This is necessary in order to prevent a fault
message from being issued as a result of the short, high current peaks occurring
during tuning of the Antenna Coupler. Once the overcurrent has diminished
again, C51 is charged via R70 with a time constant of 820ms, and consequently,
CMCCPL is maintained at H level for at least 400ms. Upon switching ON the
transceiver, V75 is conductive until C89 is charged at about 4.3V via R100 and
R101. Thus, C51 is charged at +5V and CMCCPL is set to L level.
Temperature sensor, R102 is mounted in the heat sink of the power transistors,
and its resistance value helps form a measurement for the cooler temperature.
If this rises above 90°C, comparator, N6-A, switches to L level, and the
CMTEMP signal is set to H level via gate D4-B. A second temperature sensor,
R107, wrapped inside the 3-phase transformer, T1, is monitoring the transform-
er winding's temperature, and switches the comparator, N5-D, to L level when
the temperature exceeds 150°C. This too results in CHTEMP = H. This initiates
an L pulse at CMINT with each change via N2-A, and can be inquired via D1-A.
Page 72
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