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August 16, 2007
6816985H01-B
6.2-16
UHF1 Troubleshooting Charts:
UHF Range 1 Receive RF Troubleshooting Chart
6.2.17UHF Range 1 Receive RF Troubleshooting Chart
NOTE: INJECT MODULATED ON CARRIER
NOTE: The presence or absense of RF signals is generally not enough
FREQUENCY SIGNAL AS REQUIRED.
Bad SINAD
No Recovered
Audio
Spray or Inject 1st IF
VHF2 1st IF:73.35MHz
VHF2 2nd IF:2.25MHz
VHF2 2nd LO:71.1MHz
into XTAL Filter FL51
to diagnose sensitivity degradations. It is best to compare signal levels
at each decision node, to the same circuit in working radio.
If present
at U401,
pin 47?
Is
2nd IF on
U401, pins 4
and 5?
Before replacing U401,
check U401 voltages.
Check for no RX audio
VOCON flowchart
Check tank
L412, C476.
Check for 3Vdc
at pin 48
Check
FL51
No
No
components L411,
Yes
Yes
MAEPF-27342-O
Check
FGU Chart
Check Mixer
(U1) circuit
VCO locked?
16.8MHz
check at pin 35
on U401?
18MHz
at ABACUS
(U401) pin
20?
Before replacing U401, check 2nd
Disconnect R418 and verify that
a 0.5V to 5V control voltage VCO
will sweep about the IF frequency
Remove SH401.
Check 2nd LO
U401, pin 38
Inject RF
into J101
Is it
symmetric
centered?
No
No
Does
the pulse
frequency
vary?
See VOCON
chart, RX
audio problems
No
1st LO
Locked?
Inject -47 dBm into J101 and
toggle signal continuously
TP403 data pulse
RF Signal
at C51?
Check
voltage at C46
RF
Signal postselector
input R37?
RF Signal
at C20?
RF
Signal at preselector
input TP1?
Check harmonic
filter (Components placed
between C192 - C193)
and antenna switch
Program filter to test
freqs. and check
varactor voltages
for both preselector
& postselector
No
No
No
No
No or
No
Check bias
voltages on
Q29
IF Signal
at L54?
Audio
Heard?
from L10 to
U401, pin 47
Check IF
spectrum at
U401, pin 47
No
Check
FGU
Chart
No
Check U401 voltages,
programming, and
10MHz clock VCO
components
No
Check IF filter
FL51. Make sure
LO is locked and
on frequency
VCO Q401. Check VCO O/P level;
Control Voltage at
Yes
Yes
Yes
Yes
Yes
Yes
Yes
O/P OK?
(on/off) while monitoring
postselector
Check preselector filter.
Weak RF
Yes
Yes
Yes
Yes
Yes
Trace IF signal
VHF Band :
0.8 - 4.5V
If voltages are not OK,
check U102, (PCIC)
Содержание ASTRO MT 1500
Страница 4: ...iv Table of Contents August 16 2007 6816985H01 B Notes ...
Страница 30: ...August 16 2007 6816985H01 B 2 1 4 VHF Overall Characteristics Vocoder Circuitry Overview Notes ...
Страница 34: ...August 16 2007 6816985H01 B 2 2 4 UHF1 Overall Characteristics Vocoder Circuitry Overview Notes ...
Страница 38: ...August 16 2007 6816985H01 B 2 3 4 UHF2 Overall Characteristics Vocoder Circuitry Overview Notes ...
Страница 42: ...August 16 2007 6816985H01 B 2 4 4 700 800 MHz Overall Characteristics Vocoder Circuitry Overview Notes ...
Страница 46: ...August 16 2007 6816985H01 B 2 5 4 900MHz Overall Characteristics Vocoder Circuitry Overview Notes ...
Страница 140: ...August 16 2007 6816985H01 B 4 4 20 700 800 MHz Detailed Theories of Operation VOCON Functional Blocks Notes ...
Страница 164: ...August 16 2007 6816985H01 B 5 6 Troubleshooting Procedures Operational Error Codes Notes ...
Страница 188: ...August 16 2007 6816985H01 B 6 1 24 VHF Troubleshooting Charts Secure Hardware Failure Notes ...
Страница 212: ...August 16 2007 6816985H01 B 6 2 24 UHF1 Troubleshooting Charts Secure Hardware Failure Notes ...
Страница 236: ...August 16 2007 6816985H01 B 6 3 24 UHF2 Troubleshooting Charts Secure Hardware Failure Notes ...
Страница 260: ...August 16 2007 6816985H01 B 6 4 24 700 800 MHz Troubleshooting Charts Secure Hardware Failure Notes ...
Страница 284: ...August 16 2007 6816985H01 B 6 5 24 900 MHz Troubleshooting Charts Secure Hardware Failure Notes ...
Страница 296: ...August 16 2007 6816985H01 B 7 1 12 VHF Troubleshooting Waveforms PP7 TX LO 7 1 11PP7 TX LO Probe point TP299 ...
Страница 301: ...6816985H01 B August 16 2007 VHF Troubleshooting Waveforms TP13 Mod In 7 1 17 7 1 16TP13 Mod In Test point TP36 ...
Страница 324: ...August 16 2007 6816985H01 B 7 1 40 VHF Troubleshooting Waveforms PP33 SPI Data 7 1 39PP33 SPI Data Probe Point R802 ...
Страница 325: ...6816985H01 B August 16 2007 VHF Troubleshooting Waveforms PP34 SPI CLK 7 1 41 7 1 40PP34 SPI CLK Probe Point R803 ...
Страница 342: ...August 16 2007 6816985H01 B 7 2 12 UHF1 Troubleshooting Waveforms PP7 TX LO 7 2 11PP7 TX LO Probe point TP299 ...
Страница 347: ...6816985H01 B August 16 2007 UHF1 Troubleshooting Waveforms TP13 Mod In 7 2 17 7 2 16TP13 Mod In Test point TP36 ...
Страница 371: ...6816985H01 B August 16 2007 UHF1 Troubleshooting Waveforms PP33 SPI Data 7 2 41 7 2 39PP33 SPI Data Probe Point R802 ...
Страница 372: ...August 16 2007 6816985H01 B 7 2 42 UHF1 Troubleshooting Waveforms PP34 SPI CLK 7 2 40PP34 SPI CLK Probe Point R803 ...
Страница 378: ...August 16 2007 6816985H01 B 7 2 48 UHF1 Troubleshooting Waveforms TP39 RX SSI Frame Sync Notes ...
Страница 390: ...August 16 2007 6816985H01 B 7 3 12 UHF2 Troubleshooting Waveforms PP7 TX LO 7 3 11PP7 TX LO Probe point TP299 ...
Страница 395: ...6816985H01 B August 16 2007 UHF2 Troubleshooting Waveforms TP13 Mod In 7 3 17 7 3 16TP13 Mod In Test point TP36 ...
Страница 418: ...August 16 2007 6816985H01 B 7 3 40 UHF2 Troubleshooting Waveforms PP33 SPI Data 7 3 39PP33 SPI Data Probe Point R802 ...
Страница 419: ...6816985H01 B August 16 2007 UHF2 Troubleshooting Waveforms PP34 SPI CLK 7 3 41 7 3 40PP34 SPI CLK Probe Point R803 ...
Страница 486: ...August 16 2007 6816985H01 B 7 5 12 Troubleshooting Waveforms PP7 TX LO 7 5 11PP7 TX LO Probe point Shield Tx_INJ ...
Страница 492: ...August 16 2007 6816985H01 B 7 5 18 Troubleshooting Waveforms TP13 Mod In 7 5 17TP13 Mod In Test point TP203 ...
Страница 501: ...6816985H01 B August 16 2007 Troubleshooting Waveforms PP22 Analog 5V 7 5 27 7 5 26PP22 Analog 5V Probe point U500 pin 5 ...
Страница 517: ...6816985H01 B August 16 2007 Troubleshooting Waveforms PP33 SPI Data 7 5 43 7 5 42PP33 SPI Data Probe Point R802 ...
Страница 518: ...August 16 2007 6816985H01 B 7 5 44 Troubleshooting Waveforms PP34 SPI CLK 7 5 43PP34 SPI CLK Probe Point R803 ...
Страница 521: ...6816985H01 B August 16 2007 Troubleshooting Waveforms TP37 RX SSI Data 7 5 47 7 5 46TP37 RX SSI Data Test Point TP403 ...
Страница 522: ...August 16 2007 6816985H01 B 7 5 48 Troubleshooting Waveforms TP38 RX SSI Clock 7 5 47TP38 RX SSI Clock Test Point TP404 ...
Страница 710: ...9 2 40 UHF1 Schematics Board Overlays and Parts Lists August 16 2007 6816985H01 B Notes ...
Страница 806: ...9 5 32 900MHz Schematics Board Overlays and Parts Lists August 16 2007 6816985H01 B Notes ...
Страница 816: ...Index 4 August 16 2007 6816985H01 B Notes ...
Страница 817: ......