Motorola Gp68 Part1 6881086c09 O Manual

March, 19976881086C09-O4-11
GP68 Portable Radios Service ManualRadio Programming Information 
Special Programming Mode (SPM)
A flashing channel number indicates that the channel is
excluded from the scan list. A channel number that lights
continuously indicates the channel is included in the scan
list. For example, a display showing  with flashing dig-
its indicates that channel 18 is excluded from the scan list.
Press the Enter Button to toggle the state of a channel
in the scan list from included to...

4-126881086C09-OMarch, 1997
Radio Programming InformationGP68 Portable Radios Service Manual
Special Programming Mode (SPM)
pause between the digits of the ID by first pressing ,
immediately followed by . However, any pauses entered
at the end of the ID are not stored.
Two medium-pitched “beeps” sound when a
pause is successfully entered, and the display
changes from ‘A’ to ‘–‘ to visually represent the
pause
Use  or  to scroll through the existing ID’s
digits. To change the PTT ID, use  to erase the...

 
March, 1997 6881086C09-O
 
5-1
 
Section 5
Troubleshooting 
Overview 
This section contains five troubleshooting tables for the following components: 
¥ Receiver  
• Transmitter
• Synthesizer
• Microprocessor
• Voltage Controlled Oscillator (VCO)
• LCD
 
Troubleshooting Charts 
Refer to following pages. 
Troubleshooting and Repair Comments 
While troubleshooting, if you determine that the reference oscillator crystal (Y201) is defective, the entire Radio Frequency
(RF) board must be replaced. When the...

 
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6881086C09-OMarch, 1997
 TroubleshootingGP68 Portable Radios Service Manual
Troubleshooting Charts
Troubleshooting Flow Chart
for Receiver
Start
Very low or no 12
 dB SINAD
Noise at spkr
when radio is
unsqu’d?
Is 1st LO at
U41 pin 3 > 2
dBm?
Inject on channel
signal at RF port,
U41 pin 1
Is 12 dB SINAD
-110 dBm?
Inject 45.1
MHz signal at
U41 pin 4
Is 12 dBS -117
dBm?
Inject a 45.1
MHz signal at 
C59
Is 12 dBS -110
dBm?
1Check IFIC
U51 (see
below)
Noise at pin 23
of IFIC U51?
Check
VCO/Synth...

 
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5-3
 GP68 Portable Radios Service ManualTroubleshooting 
Troubleshooting Charts
Troubleshooting Flow Chart
for Transmitter
Start
No
Power
Is
+5vTX and TXB+
OK?
Is
current
OK?
Is
VCTL
High or Low?
Check Pin 
to Q101
Is 
Pin
OK?
Check
U303, Q152
&
U151
Check
Voltages in
Power Control
Circuit
Check
Voltages in
PA Line-upTroubleshoot
VCO
DoneIs
Power
OK?
1. Check Pin Diodes
2. Check Harmonic Filter
Inspect/Repair
TX Output
Network
NO
NO
LOW
HIGH
YES NO NO
YESYESYES
NOTE
When using...

 
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6881086C09-OMarch, 1997
 TroubleshootingGP68 Portable Radios Service Manual
Troubleshooting Charts
Is information
from mP U401
correct?
Is U201 Pin 18
AT4.65 VDC?
Is U201 Pin 32
AT = 13 VDC
Is U201 Pin 1
4.3 VDC in TX?
Troubleshooting Flow Chart
for Synthesizer
Start
Visual 
check of the 
Board OK?Correct
Problem
Check 5V
Regulator
+5V at U201
Pin’s
3,12,19,22
& 23?Is 16.8MHz
Signal at
U201 Pin 14?Check
Y201,C205,C206,C211
R207 and CR203
Are signals
at Pin’s 9 &
10 of U201?
Check C202,...

 
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5-5
 GP68 Portable Radios Service ManualTroubleshooting 
Troubleshooting Charts
 
Troubleshooting Flow Chart
for Microcontroller 
START
APPLY POWER TO RADIO AND
WAS GOOD OR BAD POWER-ON
YES
DONE WAS GOOD POWER-ON BEEP ARE ALERT TONES
ENABLED IN SPM
USE SPM TO ENABLE TONES
INVOKE FACTORY
RESET IN SPM
WAS GOOD POWER
ON BEEP PRESENT
MAIN RADIO BOARDS MUST BE
REPLACED
ARE TONES PRESENT
ON POWER UP AT
U402 PIN 23?
AUDIO PROBLEM, TROUBLE-
SHOOT AUDIO CKT WITH POWER CONNECTED TO...

 
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6881086C09-OMarch, 1997
 TroubleshootingGP68 Portable Radios Service Manual
Troubleshooting Charts
4.3 VDC at
U251 Pin 5?
4.65 VDC at
U251 Pin 13?
=151 mVrms
at “+” Side
of C217?
4.65 VDC
at CR252?
0.01 VDC at
U251 Pin 17?
Are U251 Pin’s
4 at 3.9VDC,
19 at 2.1VDC,
16 at 0.9VDC,
15 at 1.7VDC,
14 at 1.4
VDC?
Is the 
Radio
UHF?
Is +5vRX
at 5V?
Is Q251
Drawing
=4mA
Is 5 VDC at
Collector of
Q251?
Are U251 Pin’s
2 at 4.2VDC,
7 at 2.1VDC,
10 at 0.8VDC,
11 at 1.6VDC,
12 at 1.2
VDC?
0.01 VDC at
U251 Pin...

 
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5-7
 GP68 Portable Radios Service ManualTroubleshooting 
Troubleshooting Charts
Troubleshooting Flow Chart
for Display Boar
d
START
DONE
APPLY POWER TO RADIO AND
TURN ON
KEYPAD
WORKING?
BACK LIGHT
WORKING? CONNECTION
OK?FIX
J801
CONNECTION
CHANGE
LCD BOARD
CONNECTION
OK?
CLOCK
WORKING?
R811, R812, R813,
R816, R817 WORKING?R814, R815,
C801 WORKING? COMPLETE
DISPLAY
CHANGE
BAD
COMPONENTS
CHANGE
BAD
COMPONENTS
LEDS
WORKING?
R801, R802, R803
WORKING?
Q801
WORKING?
CHANGE
U801...

 
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6881086C09-OMarch, 1997
 TroubleshootingGP68 Portable Radios Service Manual