Specifications

Firing Order Diagram to determine which set of eight RF
Amplifiers is connected to that interlock.
For example:
If DS3 is illuminated RED on the A27 Modulation En-
coder then RF Amplifiers RF101 through RF108 or the
encoder cable is not connected or open. This example will
be used for the rest of the troubleshooting procedures, and
applies to any other interlock that is illuminated RED.
To find a Module/Cable interlock fault, based on the above
example, use the following procedures:
b. Use an ohmmeter to measure for continuity from Cathode
of CR39 to R122 (J3-9 to J3-19). If the resistance meas-
ures open, then disconnect the J3 plug and measure for
continuity from J3-9 to J3-10 and the continuity from
J3-19 to J3- 20.
1. If the resistance from 9 to 10 is open, the cable that
connects to J18 on RF Combiner Motherboard, A13,
is open or RF Amplifiers RF101 through RF104 are
not properly making connection to the RF Combiner
Motherboard edge connectors.
2. If the resistance from 19 to 20 is open, the cable that
connects to J19 on RF Combiner Motherboard, A13,
is open or RF Amplifiers RF105 through RF108 are
not properly making connection to the RF Combiner
Motherboard edge connectors.
3. Try pulling out each RF Amplifier and pushing it back
into the connector, verify that the cables are properly
inserted into the connectors on theRF Combiner Moth-
erboard, and if needed ohmmeter check the encoder
cable wires.
c. If the ohmmeter resistance from J3-9 to J3-19 measures 0
Ohms, disconnect the J3 plug and check the resistance
across CR39. A normal diode reading should be obtained.
If not then troubleshoot the Modulation Encoder by refer-
ring to the Troubleshooting portion of Section L, Modu-
lation Encoder.
6.4.16.2 Driver Encoder Module/Cable Interlock
If DS8 is illuminated RED on the Driver Encoder, then one of
the Driver amplifiers or the encoder cables is not connected or
open.
a. Using an ohmmeter, measure for continuity from J2-20 to
J2-9. If continuity exists, then disconnect J2 and repeat
the measurement. The resistance should rise. If not, trou-
bleshoot the Cable Interlock circuitry by referring to the
Troubleshooting section for the Driver Encoder.
b. If there is no continuity between J2-20 and J2-9 then
disconnect J2 from the Driver Encoder and measure for
continuity between P2-20 and P2-19 and between P2-9
and P2-10.
1. If the resistance from 19 to 20 is open, the cable that
connects to the Driver Combiner Motherboard is open
or one of 4 Driver Amplifiers is not properly making
connection.
2. If the resistance from 9 to 10 is open, the cable that
connects to the Driver Combiner Motherboard is open
or one of 4 Driver Amplifiers is not properly making
connection.
c. Using an ohmmeter, measure for continuity from J1-20 to
J1-9. If continuity exists, then disconnect J1 and repeat
the measurement. The resistance should rise. If not, trou-
bleshoot the Cable Interlock circuitry by referring to the
Troubleshooting section for the Driver Encoder.
d. If there is no continuity between J1-20 and J1-9 then
disconnect J1 from the Driver Encoder and measure for
continuity between P1-20 and P1-19 and between P1-9
and P1-10.
1. If the resistance from 19 to 20 is open, the cable that
connects to the Driver Combiner Motherboard is open
or one of 4 Driver Amplifiers is not properly making
connection.
2. If the resistance from 9 to 10 is open, the cable that
connects to the Driver Combiner Motherboard is open
or one of 4 Driver Amplifiers is not properly making
connection.
WARNING
ENSURE THAT THE TRANSMITTER IS TURNED OFF AND ALL
PRIMARY POWER IS TURNED OFF ATTHE WALL DISCONNECT
SWITCH BEFORE OPENING ANY DOOR OR PANEL. BEFORE
REMOVING PANELS OR OPENING DOORS, VERIFY THAT THE
RF AMP POWER SUPPLY IS DISCHARGED BY CHECKING
“PA+VDC” ON THE FRONT PANEL MULTIMETER. USE A VOLT-
METER TO VERIFY THE POWER SUPPLIES HAVE BEEN DIS-
CHARGED PRIOR TO TOUCHING ANY COMPONENTS.
e. Try pulling out each Driver Amplifier and pushing it back
into the connector, verify that the cables are properly
inserted into the connectors on the Driver Combiner
Motherboard, and if needed ohmmeter check the Encoder
cable wires.
6.4.17
Encoders Supply Fault
If the transmitter has shut itself off, and the above LED is
illuminated RED, a power supply on one of the Modulation
Encoders, or on the Driver Encoder has failed. The first step is
to determine if it is a Modulation Encoder or Driver Encoder
Fault.
a. Depress S6, and observe DS9 on each Modulation En-
coder and DS7 on the Driver Encoder.
6.4.17.1 Modulation Encoder Supply Fault
a. If DS9 on a Modulation Encoder is illuminated RED,
depress S6 on that encoder and hold for a few seconds
while observing DS8, B+ and DS11, B-.
b. DO NOT DEPRESS S6 FOR LONGER THAN 1 M-
INUTE.
1. If either of the LEDs do not illuminate GREEN, check
for -10VDC at TP22 and +10VDC at TP10. If either of
these voltages are not present, troubleshoot the low
voltage supplies.
888-2339-002 6-9
WARNING: Disconnect primary power prior to servicing.