Specifications

c. If these voltages are correct a true Supply Fault exists.
Refer to the Transmitter Troubleshooting Section to locate
the Supply fault.
J.7.5.1.2 RF Amp Supply Fault Returns
a. If the fault returns and the Supply current meter does not
deflect upward, start troubleshooting by checking the volt-
age on TP30 of the analog input board.
b. If this is a logic high, the Analog Input board is not
generating the fault. Refer to the Controller, Transmitter
Interface Sections and Overall Wiring Diagram to track
down the fault.
c. If TP30 is a logic low, check the voltages on TP23 and
TP24 and compare them against the Factory test data.
d. If the voltage on either test point is different from the test
data check R113, R118, U13 and the +15 Volt supply.
e. If TP23 and TP24 measure correctly, check TP4 for a logic
high when the transmitter is turned on.
f. If TP4 is high, DS5 should also illuminate.
g. If TP4 is a logic high check TP25 for a voltage less than
what was measured on TP23 when the transmitter is turned
on.
h. If TP25 is greater than TP23 then, suspect a failed U11 or
incorrect sample from the Controller.
i. If TP25 is less than TP23, measure the voltage on TP26
when the transmitter is turned on and compare it to the
voltage on TP24.
j. If TP26 is higher than TP24 suspect a failed U11.
k. If TP26 is less than TP24, suspect a failed U13.
J.7.5.2 Max Power Adjust
If the fault is a true power supply current fault, and not a sensing
problem, then there could be a problem with the DC level being
added to the audio. Proceed as follows:
a. First, with the transmitter OFF, check the MAX POWER
ADJUST circuit.
b. Measure TP15 for -1.15VDC (within 0.2VDC) with no
audio. A voltage reading more negative than -1.35VDC
would indicate a malfunction of U3 or a misadjustment of
the MAX POWER ADJUST, R56.
c. If TP15 is too far off,measure TP14.It should measureone
half of the voltage on TP15. If not, replace U3.
d. If TP15 is within range, move on to the Power Supply
Correction circuit.
J.7.5.3 Power Supply Correction
a. IfTP15 measures correctly, check TP11. It should measure
-1.25VDC (within 0.2VDC).
b. If not, measure TP2. It should be approximately 0VDC.
c. IfTP2 measures correctly, and TP11 does not, replace U16.
d. If TP11 and TP2 both measure correctly, then with the RF
Mute ON, turn the transmitter on and measure TP2 again.
e. TP2 should measure approximately 5.6VDC.
f. If not, place jumper J5 in the Bypass position, 2-3, and
again check TP2 for approximately 5.6VDC.
g. If present, refer to the overall wiring diagram to trace the
missing correction voltage.
Note
If the sample is in the Bypass Mode, power level will not track
changes in power line variances, and higher than normal low
frequency THD may be noticed.
J.7.6 Power Control
Power control faults can be classed into four areas: Power Con-
trol, Fine Power Control, Power Step Up and Foldback. These
areas all have an effect on the (Audio + DC) circuitry.
J.7.6.1 Power Control
If the transmitter appears “stuck”in one powermode eventhough
the front panel indicators show a different power level has been
selected:
a. Turn off the transmitter and move P4 to the Bypass posi-
tion.
b. Turn the transmitter back on and adjust Bypass Power
Level (R68) for the power output desired.
1. If R68 has no effect suspect U8 and or a fault on the
A-D Converter board.
2. If the power can be changed by R68, turn off the
transmitter and put P4 back in the normal position.
c. Turn on the transmitter and adjust the potentiometer on the
Analog Input board R65, R67 or R66 for the selected
power level.
d. If this has no effect on the power output, check the input
of U17 for a high (+15V) on pins 9(Low), 10(Med),or
11(High) when a power level is selected.
e. If the high is present change U17.
f. If the high is not present when a power level is selected
suspect U14 or U25.
J.7.6.2 Fine Power Control
a. If the fine power control (Raise, Lower function) does not
operate on any power level suspect U18 or U7.
b. If the fine power control does not work at some power
levels, suspect the PAL for that power level. (U21 for High,
U20 for Medium and U19 for Low power.) These PALS
have the same program and can be interchanged to verify
that a PAL is defective.
J.7.6.3 Foldback
If the transmitter is in Foldback check the inputs to U25 at pins
1, 3, and 5 to verify that a fault with this board exists.
a. If any of these pins are a logic high a fault is being
generated from the Controller. Refer to the Controller and
Transmitter Troubleshooting Section to Continue.
b. If the inputs to U25 are low check TP36, TP35 and TP34
for a high of +15 VDC.
c. If any of these inputs are high suspect U25 or U14.
d. If the testpoints measure a logic low suspect U12.
888-2339-002 J-7
WARNING: Disconnect primary power prior to servicing.