Specifications
WARNING
ENSURE THAT THE TRANSMITTER IS TURNED OFF AND ALL
PRIMARY POWER IS TURNED OFF AT THE 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.
2. If the supply is present check R20, on the Driver
Combiner Motherboard, for an open.
3. If R20 checks correct, then check for continuity (low
resistance) from J32-1 to pins 1 through 4 on Buffer
connector J1.
4. If no continuity refer to the paragraphs that follow.
CAUTION
It may be necessary to remove the Efficiency Coil Board to accomplish
this. DO NOT attempt to turn on the transmitter with this board removed,
as AMPLIFIER DAMAGE WILL RESULT.
5. If continuity exists, check for continuity from pins 1
through 4 on the Buffer connector J1 to pins 23 through
26 on Predriver connector J2. (The Buffer Amplifier
should be in its connector).
6. If continuity exists, suspect a bad connector.
7. If this line measures open, check for continuity be-
tween pins 1 through 4 on J1 to pins 23 through 26 on
Buffer connector J1 with Buffer Amplifier in place.
8. If continuity exists, then a trace is open between J1 and
J2.
9. If no continuity then suspect a bad J1 or open F1 on the
Buffer Amplifier.
10.If no continuity exists between J32-1 and Pins 1
through4onJ1thenremovetheBufferandPredriver
modules.
C.5.2.2 Verify Predriver Select Relay Operation, K1 and K2
a. Switch between Predriver A and B on the Driver Encoder
Board and verify that K1 and K2 are operating.
1. If only one relay operates the non-switching relay is
defective or a trace is open.
2. If K1 operates but there is no continuity between J32-1
and Pins 1 through 4 on J1 in the “A” position then
suspect bad contacts of K1 or an open trace.
3. If K1 operates and there is no continuity between J32-1
and Pins 7 through 12 on J1 in the “B” position, suspect
bad contacts of K1 or an open trace.
b. If K1 and K2 do not operate check for +15VDC on J31-
17 when A is selected and for 0 VDC when B is selected.
1. If J31-17 does not change states, check for an open
trace on the board or open cable coming from the
Driver Encoder. Refer to the Driver Encoder Trou-
bleshooting Section to continue.
c. If the signal changes state but the relays do not operate,
an open coil on K1 or K2, or a shorted CR7 may be at
fault.
C.5.2.3 No RF Out of Predriver A or B
a. Verify that it is not an amplifier fault by swapping the
Predriver with another position Driver Amplifier.
b. If still no output, check for turn on signal presence during
step start (Green LED on).
1. If no signal is present, check for an open trace on the
motherboard or an open cable from Driver Encoder.
2. If no problem is found, refer to the Driver Encoder
Troubleshooting Section.
c. Check for Supply Voltage for the Predriver during Step
Start sequence with the PREDRIVER +VDC position on
the Driver Multimeter.
1. If the voltage is present at the meter, then check the
PREDRIVER IDC reading. No current indication
would mean the voltage is not getting to the Predriver
module.
2. If the voltage or current reading is not present, then
refer to “No Predriver A or B Voltage” of this section
to troubleshoot loss of the supply.
d. Remove the Predriver Module and verify that K2 on the
Motherboard operates when the Predrivers are selected on
the Driver Encoder.
1. If K2 does not operate refer to previousparagraph titled
“Verify Predriver Select Relay Operation, K1 and K2".
e. Determine that RF drive is getting to the Predriver during
the Step Start sequence. Refer to Section VI, Trou-
bleshooting, Paragraph Title “Measuring RF Drive
Level”.
1. If no Drive is present at the Predriver, refer to the Buffer
Amplifier Troubleshooting Section and/or inspect the
motherboard for an open trace or bad connector.
C.5.3
Loss of Metering and\or RF Sensing
The metering and RF sensing circuits are all connected to J31
on the motherboard.
To begin:
a. Verify the presence of the signal on the connector.
1. If missing, an open resistor, shorted diode, or open
trace associated with that metering circuit on the moth-
erboard may be at fault.
2. If present refer to the overall wiring diagram to trace
the wiring to the proper board.
C-4 888-2339-002
WARNING: Disconnect primary power prior to servicing.