Motorola Cdm And Pro Series Detailed 68p81091c63 O Manual

Maintenance3-7
3.7 Receiver Troubleshooting Chart
Bad SINAD
Bad 20dB Quieting
No Recovered AudioSTART
Audio at pin 8 
of U3101?Check Controller (in the case of no audio).
Or else go to “B” Ye s
No
Spray or inject 44.85MHz 
into XTAL Filter FL3101.
Audio heard?BYe s
No
Check 2nd LO 
(44.395MHz) at C3135. 
LO present?BYe s
 Check volt-
ages on 
U3101. OK?
Biasing OK?
No
No
A
Ye sCheck Q3102 bias 
for faults.
Replace Q3102.
Go to B
Ye s
No
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
Check cir-...

3-8Maintenance
IF Signal at 
C3101?
No
RF Signal at 
T4051?
RF Signal at 
C4015?
No
RF Signal at 
C4009?
No
RF Signal at 
C4025?
No or 
Check harmonic filters L4491-L4493, C4492 
and ant.switch D4471,D4472,L4472.
Check filter between 
C4025 & C4009. Check 
tuning voltage at R4060.
Inject RF into J4401
Is tuning volt-
age OK?
No
Ye s
Check RF amp (Q4003) 
Stage.
Check filter between 
C4015 & T4051.
Ye s
Check T4051, T4052, 
D4051, R4052, L4008.
Ye s
1st LO level 
OK?
Locked?Ye s
Check FGU
Ye s
Trace IF...

Maintenance3-9
3.8 Synthesizer Troubleshooting Chart
5V
 at pin 6 of 
D4201
Is information
from 
mP U0101
correct?
Is U4201 Pin 47
at = 13VDC
Is U4301 Pin 19
4.5 VDC in TX?  
(at VCO section)
Start
Visual 
check of the 
Board OK?Correct
Problem
Check 5V
Regulator
U4211
+5V at U4201
Pin’s
13 & 30?
Is 16.8MHz
Signal at
U4201 Pin 19?
Check Y4261, C4261, 
C4262, C4263, D4261 
& R4261
Are signals
at Pin’s 14 &
15 of U4201?
Check 
R4201
Check C4381
Is U4201 pin 2  
>4. 5 VD C i n Rx  &  

3-10Maintenance
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Maintenance
3-11
3.9 VCO Troubleshooting Chart
l
LOW OR NO RF SIGNAL
           AT TP4003VISUAL CHECK
OF BOARD
OK?4.5V DC AT
U4301 PIN 14&1835mV DC AT
U4301 PIN 19ARE Q4301
BASE AT 2.4V
EMITTER AT 1.7V COLLECTOR AT 4.5V
CORRECT
PROBLEM  NO
YES
MAKE SURE SYNTHESIZER IS
WORKING CORRECTLY AND
RUNNER BETWEEN U4201 PIN 
28 AND U4301 PIN 14&18 IS OK.
CHECK RUNNER
BETWEEN U4201 PIN 2
AND U4301 PIN 19REPLACE Q4301
IS RF AVAILABLE 
AT BASE OF Q4332
IF ALL PARTS FROM U4301
PIN 8 TO BASE OF Q4332 ARE 
OK, REPLACE...

3-12Maintenance
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4-1
Chapter 4
Schematic Diagrams, Overlays, and Parts Lists
4.1 Introduction
This chapter provides schematic diagrams, overlays, and par ts lists for the radio circuit boards and 
interface connections.
4.1.1 Notes For All Schematics and Circuit Boards
* Component is frequency sensitive. Refer to the Electrical Par ts List for value and usage.
1.
Unless otherwise stated, resistances are in Ohms (k = 1000), and capacitances are in picofarads 
(pF) or microfarads (µF).
2.
DC voltages are measured from...

4-2Introduction
LAYER 1 (L1)
LAYER 2 (L2)
LAYER 3 (L3)
LAYER 4 (L4)
LAYER 5 (L5)
LAYER 6 (L6)
INNER LAYERS SIDE 1
SIDE 2
6-LAYER CIRCUIT 
COPPER STEPS IN PROPER 
LAYER SEQUENCE BOARD DETAIL VIEWING 

4-3
D0871 D0872
D0873
D0874
D0875
D0876 D0877D0878D0879
D0881 D0884
D0885 D0886
D0887
D0888 2 3 5 7 9
864 10
J0811JU0852 JU0853
JU0854 4
1
235 R0823
S0861
S0862 S0863 S0864S0865 S0866
ZWG0130114 1
Figure 4-1.  PRO3100/CDM750 Control Head Top Overlay   

4-4
0
C0802
C0803
C0804
C0805
C0806
C0808
C0809
C0810C0811
C0813
C0815
C0816C0817
C0818
C0819 C0821
C0822 C0823C0824
C0831 C0832 C0833
C0843 D0821
D0822
D0831
12J0801
1
2 P0801Q0821Q0822 Q0823
Q0841
Q0843Q0871 Q0872
Q0873
Q0874
Q0875 Q0876Q0877
Q0878
Q0879
Q0881
Q0885R0810
R0811
R0812
R0813
R0814
R0815 R0816
R0821
R0822
R0824 R0825
R0831
R0832
R0833
R0834 R0835
R0836 R0837
R0838
R0839R0841
R0842R0843
R0844
R0845R0847
R0849 R0852 R0853R0854
R0861R0862R0864
R0866R0867R0871 R0872
R0873
R0874
R0875...