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DVOR 432
Fault Location
Step
Fault (5 cont.)
A
5.2.1.3
The synthesizer does not os
cillate in the range from 108 to
118 MHz.
Synthesizer output level too
low
5.2.1.4
Power generated by the
MOD-SBB in the ASU too
low. The blending function is
not correctly set.
5.2.1.5
The transmitter generates suf
ficient SB power. All results of
5.2.1.2 are ok. Blending func
tions are correctly set.
Power of blending modulators
is too low.
5.2.2
Side band and carrier phases do not match.
5.2.2.1
Wrong carrier
First check carrier phase.
phase (CSB)
This value is not dependent
from the adjustment.
5.2.2.2
Wrong SB
Sideband phase set cor
phase
rectly?
Sideband phase correct?
Phase control voltage for both
SB modulators ok?
6-6
Operation and Maintenance
B
MON1/2 Measurement:
Upper Sideband Frequency
SB1?
Lower Sideband Frequency
SB2?
TX1/2 BITE Digital:
Level SB1: BFSB1 ok?
Level SB2: BFSB2 ok?
TX1/2 Adjustments ASU:
SBA Sinus Blending (SB1)
SBA Cosinus Blending (SB1)
SBB Sinus Blending (SB2)
SBB Cosinus Blending (SB2)
TX1/2 BITE ASU:
BLEND_SB1_SINUS
faulty?
BLEND_SB1_COSINUSfaulty?
BLEND_SB2_SINUS
faulty?
BLEND_SB2_COSINUSfaulty?
TX-1 Measurement:
CSB RF Phase Measurement.
TX1/2 BITE ADC-1:
BU_MOD_C1?
TX1/2 Miscellaneous:
MOD-CSB-1 Sign Control?
BU_MOD_C1 should lie within
the range from +2V to +8V.
Phase adjustment of carrier is
not possible if BU_MOD_C1
lies between -0.5 and +1.5 V
or between 9 and 27 V.
TX1/2 Adjustments:
SB RF Phase?
SB RF Phase control voltage?
TX1/2 Measurement:
SB RF Phase Measurement
Fault <10° is ok.
TX1/2 BITE ADC-2:
ControlSB2P_ST_3
TX1/2 BITE ADC-1:
BU_PH_SB2, original value?
TX1/2 BITE ADC-2:
ControlSB1P_ST_3
TX1/2 BITE ADC-1:
BU_PH_SB1, original value?
C
If the frequency is wrong,
replace SYN.
Level too low, replace
SYN.
All values set correctly?
At least one signal is set
lower than the original va
lue. Replace in ASU:
- MOD-SBB/1
- MOD-SBB/1
- MOD-SBB/2
- MOD-SBB/2
If all values are ok, conti
nue with 5.2.2 SB Phase
Is the original value of ±5°
reached?
Do both have the original
value?
Replace:
- MOD-110 (CSB)
- CCP-D
- (possibly MSG-C )
A phase deviation results
in a lower Mod. depth of
the 9960 Hz auxiliary car
rier.
Deviation >1V, replace
MSG-S
If no, replace MOD-110
(SB2)
Deviation >1V, refer to
5.2.2.3
If no, replace MOD-110
(SB1)
Ed. 01.04
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