Harris HTlFM - Page 37

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PROBLEM
Apparent interference to a
TV
channel close to the
RF
Carrier
2nd Harmonic.
Troubleshooting Controller
POWER SUPPLY
TROUBLESHOOTING
PROCEDURES
POSSIBLE CAUSES POSSIBLE SOLUTIONS
1.
Overload
of
TV from
FM
carrier at
1.
Trap
out
the
FM
carrier
at
the
the fundamental frequency. When
TV
input to the TV set.
input is overloaded, the TV input am-
plifier will develop power at twice the
FM
Carrier frequency.
+20 VOLTS (Positive end
of
ca-
1.
Loose connector J2.
pacitor C42) missing or -20
1.
Check the connectors at both ends
of
the cable which connects J2
of
the
Controller printed-circuit board to
the filter/connector in the rear wall
of
the Controller enclosure, and both
ends
of
the Power cable to the Con-
troller from the
AC
Distribution
Panel.
VOLTS (Negative end
of
capaci-
tor C43) missing.
+15 VOLTS
(TPll)
missing.
+B VOLTS (TP15) missing.
-15 VOLTS (Anode end
of
diode CR7) missing.
TRI-STATE CONTROL is in
the
"HIGH"
state.
POWER ENABLE is in the
"LOW"
state.
OPERATING
CIRCUITS
TX
ON
circuit does not start
transmitter.
1.
Regulator integrated circuit
Ul
"open".
2. Diode CR27 "open".
3. +15-VOLT circuit "shorted".
1.
+15 VOLTS missing
2. Diode CR40 "open".
1.
Regulator integrated circuit U2
"open".
2. Diode CR35 "open".
3. -15 VOLT circuit "shorted".
1.
+15 VOLTS low
or
missing (includ-
ing power failure).
1.
Replace integrated circuit
Ul.
2. Replace diode CR27.
3. Relieve the "shorted" condition.
1.
Restore +15 Volts
2. Replace diode CR40.
1.
Replace integrated circuit U2.
2. Replace diode CR35.
3. Relieve the "shorted" condition.
2. Diode CR47 "open". 2. Replace diode CR47.
3. Integrated circuit
Ul
7 A defective. 3. Replace integrated circuit
Ul
7.
1.
TRI-STATE CONTROL
is
in the
1.
Refer
to
the TRI-STATE
CON-
"HIGH" state. TROL is in the "HIGH" state section
on the discussed previously in this
table.
2. Integrated circuit
Ul
7B
defective. 2. Replace integrated circuit
Ul
7.
3. POWER ENABLE circuit 3. Relieve the short.
"shorted".
1.
Failsafe interlock open.
1.
Troubleshoot and repair.
888-2312-001
5-7
WARNING:
Disconnect primary power prior to servicing.