Specifications
One is an RF MUTE at the collector of Q2 to turn all Big Step
and Binary RF Amplifiers off. The other is a Supply Fault, when
Q1 turns on, which shuts the transmitter OFF.
J.7 Troubleshooting
J.7.1 Power Supply
If an Analog Input supply fault is displayed on the Control front
panel, then with only the low voltage on, check the LED indica-
tors on the Analog Input board:
a. DS1 (+5V)
b. DS2 (-15V)
c. DS3 (+15V)
Each of these LED indicators should be Lit, if the individual
supplies are operating normally.
J.7.1.1 DS4 Illuminated
DS4 will light under 2 basic conditions,
a. If any of the Low voltage supplies or regulators fail, or
b. If one of the regulated outputs is less than 80% of normal.
This means that DS1, DS2, or DS3 could be lit and a supply
fault still be detected, turning on DS4. The input supply
voltages and the regulated supply voltages will have to be
checked closely to determine why DS4 is lit.
J.7.1.2 No +5V (DS1 out)
a. If DS1 is not illuminated, check fuse F2 and replace if
necessary.
b. If F2 is not open, measure TP18 for +8VDC.
c. If TP18 does measure +8VDC, replace U22.
d. If TP18 does not measure +8VDC then refer to the overall
wiring diagram and the Transmitter troubleshooting sec-
tion to troubleshoot a problem with the Low Voltage Sup-
ply.
J.7.1.3 No -15V (DS2 out)
a. If DS2 is not illuminated, check fuse F1 and replace if
necessary.
b. If F1 is not open, measure TP17 for -22VDC.
c. If TP17 does measure -22VDC, replace U23.
d. If TP17 does not measure -22VDC then refer to the overall
wiring diagram and the Transmitter troubleshooting sec-
tion to troubleshoot a problem with the Low Voltage Sup-
ply.
J.7.1.4 No +15V (DS3 out)
a. If DS3 is not illuminated, check fuse F3 and replace if
necessary.
b. If F3 is good, measure TP29 for +22VDC.
c. If TP29 does measure +22VDC, replace U24.
d. If TP29 does not measure +22VDC then refer to the overall
wiring diagram and the Transmitter troubleshooting sec-
tion to troubleshoot a problem with the Low Voltage Sup-
ply.
J.7.1.5 All LED Indicators lit (except DS4)
If all the LED indicators are lit, it is possible the fault sensing
circuitry has failed. Procede as follows,
a. Check TP22 for +5VDC and replace U29 if necessary.
b. If TP22 is okay, measure the voltage on TP42.
c. If this is a logic high, the signal is correct and no fault exists
on this board. Refer to the Controller section of the manual
and to the transmitter overall wiring diagram to continue
troubleshooting this fault.
d. If the TP42 is low, and TP19, TP20, and TP21 have the
correct voltages, then troubleshoot U15 and associated
circuitry and replace if necessary.
J.7.2
Audio Input
Problems in this circuit would be characterized by:
a. Poor high frequency Response, or
b. No audio with carrier present
J.7.3
Poor High Frequency Response
The circuitry that would effect this problem on the Analog Input
board is the Bessel Filter.
a. Verify that P1 and P2 are in the correct position for the
source impedance of the generator.
b. For more information on this, see the Installation section
on setting Audio Source Impedance.
c. Ifthe proper position is selected, check R39, R49, C20 thru
C23 and L5 through L7.
J.7.4
No Audio but Normal Carrier is Present
a. Verify that audio is connected to the transmitter and P1 and
P2 are in the correct position.
b. Check TP12 for an audio signal.
1. If present, suspect U3.
2. If the signal at TP12 is not symmetrical suspect U1.
3. If it is not present, replace U1.
J.7.5
RF Amp Power Supply Current Fault
Several areas on this board could cause an RF Amplifier Power
Supply Current Fault. These include:
a. Overcurrent Sensing
b. Max Power Adjust
c. Power Supply Correction
J.7.5.1 Overcurrent Sensing
If the Control front panel displays an RF Amp Power Supply
Current fault, apply an RF Mute with S1 on Controller board and
turn on the transmitter.
J.7.5.1.1 RF AMP Supply Fault Does Not Return
a. If the RF Amp supply fault does not return after the RF
Mute is applied, check the voltage on TP23 and TP24 and
compare them against the factory test data.
b. If they are not correct check R113 and R118.
J-6 888-2339-002
WARNING: Disconnect primary power prior to servicing.