Specifications

E.6.23.1 Regulator Status
In order to be able to have an on-board visual status indication
of regulator operation, it is necessary to have a supply voltage on
the board that does not depend on the regulated supplies. The
+22VDC supply goes to CR9 and CR11 and +8VDC goes
through CR12 to a 5 Volt regulator, U33. This +5 Volts is
designated +5VB and can be measured at TP19.
The +5VB is used as a reference to inputs of comparator U32
through a series voltage divider network. Each supply is con-
nected to a voltage divider and then connected to the other inputs
of the comparator. With the non-inverting inputs more positive
than the inverting inputs the comparator output is a logic high.
This is the NORMAL condition with no faults.
If one of the regulated supplies fails or drops low by more than
20%, the corresponding comparator output will go logic low.
DS7 Supply Fault will be illuminated RED and transistor Q8 will
turn on, pulling the voltage at J3-3 low.
This will cause the transmitter to turn OFF, and the Encoder
Supply Fault LED on the Control front panel will be illuminated
RED.
E.7 Troubleshooting
Circuitry on this board can be classified into these major areas:
a. Power Supply
b. Fault Sensing
c. Driver Control
d. A/D Phasing and
e. Cable Interlock.
Refer to the corresponding section for the area being addressed.
E.7.1
Power Supply
If an Encoder supply fault is displayed on the Control front panel,
and with only the low voltage on, check the LED indicators on
the Driver Encoder:
a. DS1 (+5V)
b. DS2 (-5V)
c. DS3 (+15V)
Each of these LED indicators should be Lit if the individual
supplies are operating normally.
a. If DS7 is illuminated RED:
b. Use the Multimeter to measure the +15VDC, +5VDC, and
-5VDC power supplies.
c. If either supply has been reduced by 20% or more:
1. Check the input fuse and replace if necessary.
2. If fuse is not open, measure input TP for the unregulated
voltage.
3. If the unregulated input is correct, replace the regulator.
d. If all supplies measure correct:
1. Check TP10 for +5VDC and replace U11 if necessary.
2. If TP10 is okay, measure the voltageson the comparator
inputs and outputs to determine if the comparator is
faulty.
E.7.2
Fault Sensing
E.7.2.1 High Drive Sensing
With the transmitter OFF, and only the Low Voltage ON, begin
troubleshooting as follows:
a. Measure the output J3-11 on this board. A logic low
indicates a fault.
1. If this point is low, unplug J7 from the board and
recheck the output.
2. If this point goes to a logic high, a fault may exist in the
wiring, Transmitter Interface, or Controller.
3. If the output remains low, check the voltage on TP5. If
it is more positive than TP7, (TP7 should read 0 Volts
with the transmitter off) replace U17.
b. If the comparator checks okay, then the drive sample could
be the problem.
1. Check the RF Drive Splitter RF Sample level across the
input at J7 during the step-start sequence.
2. If it is higher than normal, inspect the transformer
assembly and associated circuitry on the Driver En-
coder and the sample connection and cables coming to
the Driver Encoder. Refer to the overall wiring diagram
as needed.
E.7.2.2 Low Drive Sensing
With the transmitter OFF, and only the Low Voltage ON, begin
troubleshooting as follows:
a. Measure the output at J3 on this board. A logic low indi-
cates a fault.
1. If this point goes to a logic High, then a fault exists in
the wiring, Transmitter Interface, or Controller.
b. If the output is low, the following can be checked during
the step-start sequence.
1. Compare the voltages at TP7 and TP6. TP7 should be
greater than TP6.
2. If it is, and the output is still logic low, replace U17.
c. If the comparator checks okay, then the drive sample could
be the problem.
1. Check the RF Drive Splitter RF Sample level across the
input at J7 during the step-start sequence.
2. If it is lower than normal, inspect the transformer as-
sembly and associated circuitry on the Driver Encoder
and the sample connection and cables coming to the
Driver Encoder. Refer to the overall wiring diagram as
needed.
E.7.2.3 Power Supply Temperature Fault
Note
Troubleshooting the Temperature indicator will require that the
fault be active at the time of troubleshooting. This procedure as-
sumes that the fault is active and cannot be reset from the Con-
trol front panel display.
888-2339-002 E-7
WARNING: Disconnect primary power prior to servicing.