LBI-38865A
Maintenance Manual
Monogram
UHF MOBILE RADIO
MODEL MGM 450
Series
ericssonz
LBI-38865
NOTICE!
This manual covers Ericsson and General Electric products manufactured and sold by Ericsson Inc.
NOTE
Repairs to this equipment should be m ade only by an authorized service technician or facility designated by the supplier.
Any repairs, alterations or substitution of recommended parts made by the user to th is equipment not approved by the
manufacturer could void the user’s authority to operate the equipment in addition to the manufacturer’s warranty.
NOTICE!
The software co nta ine d in this devi c e is co py right e d by E ric sson Inc . Unpu bli she d right s a re re ser ve d und er the copy rig ht
laws of the United States.
This manual is published by Ericsson Inc., without any warranty. Improvements and changes to this manual necessitated
by typographical e rror s, inacc uraci es of cu rr en t infor ma tion, o r im prov em en ts to prog ra ms and/or equ ipm ent, ma y be made
by Ericsson Inc., at any time and without notice. Such changes will be incorporated into new editions of this manual. No
part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including
photocopying and recording, for any purpos e, without the express written permissi on of Ericsson Inc.
Copyright © Nove mber 1994, Ericsso n, I nc.
ii
MONOGRAM SERIES LBI-38865
TABLE OF CONTENTS
TABLE OF CONTENTS
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
RECEIVER (PER EIA RS-204-C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
TRANSMITTER (PER EIA RS-152-C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
OPTIONS AND ACCESSORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
UNPACKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
DESCRIPTION OF CONTROLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-13
RECEIVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
TRANSMITTER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
PREVENTIVE MAINTENA NCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-16
TOP AND BOTTOM COVERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
FRONT PANEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
RF BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
DIGITAL BOARD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
PROGRAMMING INSTRUCTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
TEST EQUIPMENT SETUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
ALIGNMEN T PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-2 2
SUGGESTED TEST EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
PROGRAMMING FOR ALIGNMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
PLL ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
TRANSMITTER ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
RECEIVER ALIG NMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
RF BOARD ALIGNMENT AND TEST POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DIGITAL BOARD ALIGNMENT AND TEST POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
PERFORMANCE TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26-27
TRANSMITTER PERFORMANCE TEST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
RECEIVER PERFORMANCE TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
COMPONENT REPLACEMEN T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-30
Page -iii-
Nov. 94
MONOGRAM SERIES LBI-38865
TABLE OF CONTENTS
ELECTRICAL PARTS LIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
PRINTED CIRCUIT BOARDS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
TOP VIEW 406136-F ISSUE: H / RF BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.1
BOTTOM VIEW 406136-F ISSUE: H / RF BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2
TOP VIEW 406137-E ISSUE: H / DIGITAL BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3
BOTTOM VIEW 406137-E ISSUE: H / DIGITAL BOARD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4
MISC. PRINTED CIRCUIT BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.5
MISC. PRINTED CIRCUIT BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.6
EXPLODED VIEW AND PARTS LIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
SCHEMATICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Page -iv-
Nov. 94
MONOGRAM SERIES LBI-38865
SPECIFICATIONS
SPECIFICAT IONS
GENERAL
Frequency Range
A Band 400-440 MHz
C Band 450-470 MHz
E Band 470-512 MHz
Channels 16 maximum
Channel Spacing 25 kHz Programmable
(In 6.25 kHz Steps)
Input Voltage 13.8 VDC Negative Ground
Current Drain
Standby 0.15 Amp
Receive 0.5 Amp
Transmit 8 Amp
Temperatur e Range -30° to + 60° C
Dimensions 2 x 6 x 8.25 inches
(51 x 152 x 210 mm)
Weight 4 lbs., 3 oz. (1.9kg )
With Mic.
FCC Compliance Parts 15, 22, 74, 90, 95
FCC ID Designation
400-440 MHz F3JSM445A
450-470 MHz F3JSM445C
470-512 MHz F3JSM445E
DOC (Canada) Type Approval
400-440 MHz N /A
450-470 MHz 287194100I
470-512 MHz N / A
Page-1Nov. 94
MONOGRAM SERIES LBI-38865
SPECIFICATIONS
RECEIVER (PER EIA RS-204-C)
RF Input Impedance 50 Ohms Nominal
Sensitivity:
(EIA 12 dB SINAD) 0.35 uV
20 dB Quieting 0.50 uV
Squelch Sensitivity 0.20 uV Threshold
Selectivity -80 dB
Intermodulation -70 dB
Modulation Acceptance Bandwidth
Spurious and Image -70 dB
Audio Power Output 5 W (@10% Dist. into 40 W Load)
Frequency Stability
Operational Bandwidth 10 mHz
±7.5 kHz
± 0.0005%
( 3dB degradation at band limits)
UHF PROGRAMMING CHART RECEIVE
Frequency Spread Band Width Factory Programmed Freq. Spreads
400-440 MHz 10 MHz 405-415 MHz
(3 dB Degradation at limits)
450-470 MHz 10 MHz 460-470 MHz
(3 dB Degradation at limits)
470-512 MHz 10 Mhz 500-510 MHz
Page-2Nov. 94
(3 dB Degradation at limits)
MONOGRAM SERIES LBI-38865
TRANSMITTER (PER EIA RS-152-C)
RF Power Output 40 Watts (adjustable)
RF Output Impedance 50 Ohms
Spurious and Harmonics -70 dBc
Modulation 16KOF 3E
FM Hum and Noise -45 dB Nominal
Audio Distortion < 3 % @ 1000Hz
Frequency Stability 0.0005%
Operational Bandwidth 20 mHz
( 3dB degradation at band limits)
SPECIFICATIONS
UHF PROGRAMMING CHART TRANSMIT
Frequency Spread Band Width Factory Programmed Freq. Spreads
400-440 MHz 20 MHz 405-420 MHz
450-470 MHz 20 MHz 450-470 MHz
470-512 MHz 20 Mhz 490-510 MHz
Page-3Nov. 94
(3 dB Degradation at limits)
(3 dB Degradation at limits)
(3 dB Degradation at limits)
MONOGRAM SERIES LBI-38865
SPECIFICATIONS
OPTIONS AND ACCESSORIES
CONTROL STATION OPTIONS:
Desk Microphone MGMC5H
Power Supply MGPS5V
NOT SHOWN:
Antenna - MGAN1A
Relay Kit - MGSU1C
Noise Suppression Kit - MGPD1A
External Speaker MGZM7C
Page-4Nov. 94
MONOGRAM SERIES LBI-38865
UNPACKING
Check the carton and packing material carefully for the following items:
1. Transceiver Unit
2. Microphone
3. DC power cord
4. Mobile Mounting Bracket
5. Assembly Hardware
6. Operating Guide
Styrofoam not us ed
Inner Packing is now ca rdboard tray box.
UNPACKING
Figure 1 - Unpacking Diagram
Page-5Nov. 94
MONOGRAM SERIES LBI-38865
INTRODUCTION
INTRODUCTION
The Conventional Monogram Series Radio is a rugged two-way FM mobile radio which operated in the 400-440
MHz, 450-470 MHz or the 470-512 MHz band split. The Monogram is a synthesized radio utilizing microcomputer
technology to provide reliable high quality simplex two-way mobile communications. Its transmitter output power
level is 40 watts over the wide bandwidth, with an allowable 10 MHz maximum receive channel separation. The
basic radio package includes the following features:
Microprocessor Control
∗
Synthesized RF Channel selection (frequency control)
∗
Vacuum Fluorescent Channel Selection Display
∗
Channel Guard (CTCSS) Encode/Decode
∗
Digital channel Guard (DCG) Encode/Decode
∗
Priority Scan
∗
±
5 PPM frequency stability
∗
Field Programmable with PC
∗
Variable Squelch
∗
Internal 5-watt Speaker, with volume control
∗
Side Mounted Microphone Connector
∗
Rear Mounted Antenna Connector (SO-239)
∗
Rear power connections
∗
The small size of the Monogram radio makes it ideal for front mounting in conventional vehicles. The radio is
operated with a simple hand held microphone in combination with the operating controls described in the following
section.
Page-6Nov. 94
MONOGRAM SERIES LBI-38865
DESCRIPTION OF CONTROLS
DESCRIPTION OF CONTROLS
FRONT PANEL CONTROLS
1. Squelch Control: The squelch control will silence the receiver when no signal is being received.
2. ON/OF/VOLUME Control: This is the main power switch and volume control.
3. Monitor Button (2): This button performs three functions:
a. Disables tone or digital squelch options when in receive mode.
b. Returns to normal radio operation from the programming mode.
c. Controls display intensity.
4. Auxiliary Speaker Button (1): This button silences the internal speaker and connects the auxiliary speaker
(requires the auxiliary option printed circuit board to be installed). It also deletes channels from the scan list
while in the programming mode.
5. SCAN Push Button (S): This button turns the scan function "ON" (indicated by a red backlight) and "OFF".
It also serves as the ENTER function during SCAN programming.
6. PRIORITY SCAN Push Button (P): This button turns the PRIORITY SCAN function "ON" (indicated by a red
backlight) and "OFF". It also provides access to the programming mode when the radio is turned on.
7. Channel Change buttons (CH): The channel change buttons allow the operator to scroll either up or down
through the programmed channels.
8. Call Light Indicator (CALL): This green Light Emitting Diode (LED) indicator illuminates to indicate
activity on the channel during receive when coded squelch or digital signaling options are used.
9. Busy Channel Indicator (BUSY): This yellow Light Emitting Diode (LED) indicator illuminates to indicate
activity on the channel during receive.
10. Transmit LED Indicator (TX): This red Light Emitting Diode (LED) indicator illuminates during transmit
mode. It also will flash to indicate that the synthesizer is out of lock.
11. Channel Display: The front panel display indicated channel number, priority scan numbers, programming
mode and error messages.
FIGURE 2 - Front Panel Controls
Page-7Nov. 94
MONOGRAM SERIES LBI-38865
DESCRIPTION OF CONTROLS
BACK PANEL CONNECTORS
1. External Speake r Co nnector: This 3.5mm di a meter jack is provide d fo r a 4 oh m external speaker. The
internal speaker is silenced when the external speaker is connected.
2. Auxiliary Speaker Connector: This 3.5mm diameter jack is provided for an auxiliary speaker (Option
MGSU1C Relay Kit is required).
3. Antenna Connector: An SO-239 type connector. The output load must be 50 ohms.
4. DC 13.8V Connector: Polarized plug for 13.8 VDC power input - FOR NEGATIVE GROUND SYSTEMS
ONLY.
FIGURE 3 - Back Panel Controls
Page-8Nov. 94
MONOGRAM SERIES LBI-38865
OPERATION
OPERATION
• NOTE: The following description briefly outlines the operation of your UHF synthesized mobile radio. Consult
the operators manual for a complete description of all the modes of operation for which the radio is capable.
RADIO ON/OFF, POWER UP
1. Turn the radio on by turning the VOLUME control one-half turn clockwise. After 4000 appears in the
display and the power up alert tone is generated, the display will change to the #1 priority channel. If no
priority channel has been programmed, the display will change to channel 1.
2. Turn the radio off by rotating the VOLUME control fully counter-clockwise.
RECEIVING A CALL
1. Turn the radio on and select the desired channel.
2. Depress the monitor button (2) if necessary to illuminate it’s backlight. Adjust the volume control to a
comfortable listening level.
3. Rotate the SQUELCH control clockwise until the squelch noise (rushing sound) is no longer present.
4. Depress the MONITOR button (2) to extinguish the blacklight.
• NOTE: If the radio is equipped with coded squelch options, depress the MONITOR button (2) to enable the
option; the CALL indicator will no longer be illuminated.
TRANSMITTING
1. Turn the radio on and select the desired channel.
2. Pick up the microphone and listen briefly to insure the channel is clear. Alternatively, leave the microphone
on-hook and depress the MONITOR button (2).
3. Depress the PTT switch on the side of the microphone. Hold the microphone one to two inches from the
mouth and speak in a normal tone of voice. The TX indicator should be illuminated.
4. Release the PTT switch when the message is completed.
Page-9Nov. 94
MONOGRAM SERIES LBI-38865
OPERATION
DIGIT AL CHANNEL GUARD
Channel Guard provides a means of restricting calls to specific radios through the use of a continuous tone coded
squelch system (CTCSS), or a multi-code digital squelch system (DCG). tone frequencies range from 67Hz to
250.3Hz. There are 83 standard programmable digital codes .
The Channel Guard tone fr eq uencies and codes are software programmable. Both tone frequencies and digital co des
may be mixed on eac h ch an nel. The frequenci es an d co des are shown in Tables 1 an d 2. A Channel Number displa y
that does not flash, indicates that Channel Guard is enabled, or that Channel Guard is not programmed. A flashing
Channel Number indicates that Channel Guard is programmed and disabled.
Table 1 - Channel Guard tone Frequencies
Standard Tone Frequencies in Hertz
67.0 71.9 74.4 77.0 79.7 82.5 85.4 88.5
91.5 94.8 97.4 100.0 103.5 107.2 110.9 114.8
118.8 123.0 127.3 131.8 136.5 141.3 146.2 151.4
156.7 162.2 167.9 173.8 179.9 186.2 192.8 203.5
210.7 218.1 225.7 233. 6 241. 8 250.3
Table 2 - Primary DCS Codes
DIGITAL SQUELCH CODES
023 114 174 266 411 506 703
025 115 205 271 412 516 712
026 116 212 274 413 523 723
031 122 223 306 423 526 731
032 125 225 311 431 532 732
036 131 226 315 432 546 734
043 132 243 325 445 565 743
047 134 244 331 446 606 754
051 143 245 332 452 612
053 145 246 343 454 624
054 152 251 346 455 627
065 155 252 351 462 631
071 156 255 356 464 632
072 162 261 364 465 654
073 165 263 365 466 662
074 172 265 371 503 664
Page-10-
Nov. 94
MONOGRAM SERIES LBI-38865
CIRCUIT ANALYSIS
CIRCUIT ANAL YSIS
RECEIVER
RF Amplifier
Incoming signals from the antenna jack are routed backwards through the transmitter lowpass filter in PIN diode
switch D16. In receive mode, D16 conducts allowing a low impedance path through the diode to the receiver front
end circuitry. The receiver RF amplifier section is comprised of two bandpass filter sections separated by an
amplifier based around Q1. These two filters allow signals at or near the operating frequency to pass but provide
strong rejection of the mixer’s spurious response frequencies. The first filter section is a two pole design formed
around RF helical resonator T1 and the associated circuitry. This filter is followed by the RF amplifier transistor Q1.
This device with its low noise figure, yields good receiver sensitivity while showing strong resistance to overload
from strong signals. The output of Q1 drives a pole filter section formed around T2 and T3. The output of the RF
amplifier stage is routed to the first mixer.
First Mixer and First IF Amplifie r
The action of the first mixer transistor Q2 is to convert incoming signals at the operating frequency to the frequency
of the first IF which is 21.4 MHz. the output of the mixer is at a frequency which is equal to the difference between
the frequency of the incoming signal and the local oscillator. In this radio, the local oscillator signal is chosen to be
21.4 MHz below the operating frequency. The device chosen to perform the mixing operation is Q2, a high
performance JFET. The incoming signal is applied to the gate of Q2 while the local oscillator is applied to the drain.
The local oscillator signal is filtered by Helical Resonator T6 and associated circuitry before being supplied to the
drain of Q2. The difference frequency signal at 21.4 MHz exits the mixer at the source of Q2 and is tuned for 21.4
MHz by T8, which drives the first IF filter XF1 and XF2. XF1 and XF2 form a 4-pole monolithic crystal filter pair
which in part determines the selectivity of the radio. The output of the crystal filter is routed to the first IF amplifier
formed around Q3. RF transformer T9 provides proper matching of the crystal filters to insure good bandpass
response and selectivity.
Second Mixer, Second IF, and FM Detector
The output of Q3 is applied to the input (pin 16) of IC2. IC2 is a single conversion FM receiver on one integrated
circuit chip. The signal at the input is routed straight to a mixer which converts the incoming signal to the second IF
frequency of 455 kHz. The second local oscillator is formed with crystal X1 and circuitry within IC2. The output of
the second mixer is at pin 3 which is connected to a ceramic bandpass filter CF1 and centered at 455 kHz. This filter,
along with XF1 and XF2, determine the adjacent channel selectivity of the radio. The output of CF1 drives a high
gain IF amplifier chain internal to IC2 which in turn drives the quadrature detector. The output of the detector is
amplified and exits IC2 at pin 9.
Audio
Detected audio from IC2 passes through a lowpass filter formed around L16, C64 and C65 which removes IF
frequency components at 455 kHz. the audio signal then passes through buffer amplifier transistor Q7 before being
filtered by a two section, 4-pole high pass filter (IC3). This filter removes DCS and CTCSS low frequency tones
from the recovered audio. Transistors Q6 and Q108 act as switches around volume control VR2 to mute the audio
during squelched receive operation. The audio signal is finally routed to audio power amplifier IC103 and then to the
speaker.
Page-11-
Nov. 94
MONOGRAM SERIES LBI-38865
CIRCUIT ANALYSIS
Squelch
The presence of an RF carrier is determined by noting the level of ultrasonic noise at the detector output (pin9) of
IC2. When a carrier is present, the noise level drops. The audio at pin 9 of IC2 is filtered by a two-pole bandpass
filter formed around L17, L18, C68 and C69. This filter passes audio at and near an audio frequency of 50 kHz. This
frequency is high enough that voice audio and its harmonics will not cause improper squelch operation. The output
of the filter is routed to an amplifier internal to IC2. The output of the amplifier drives Q4. The DC voltage at the
detector output is amplified and filtered by Q4. The output of Q4 send its squelch signal to the microprocessor.
When the microprocessor determines that a valid carrier exists, it sends an unmute signal to the audio switch
transistors Q6 and Q108.
TRANSMITTER
Audio
The microphone audio is amplified, pre-emphasized and peak limited by circuits within IC113. The output of the
limiter is routed through RV4, the microphone deviation control. Input CTCSS and DCS signals are routed through
RV5, the CTCSS/DCS deviation control. Both signals are summed through a lowpass filter formed around IC114 to
remove high frequency components from the limiter which could cause channel splatter. When the microprocessor
enables the TX 8 volt supply, analog gate IC115 delivers the modulation signal to the VCO transistor Q115 by
changing the capacitance of D123 and D110.
RF Driver and Power Amplifie r
Diode D11 acts as a switch allowing the RF signal from the phase locked loop frequency synthesizer to pass through
the RF driver and power amplifier during transmit, but not during receive. Buffer amplifier Q10 amplifies the carrier
to the level needed by the driver amplifier stages. The driver amplifiers, of which the last 2 stages are gain controlled
by the automatic power control, drive the final amplifier stage formed around Q14. The final amplifier boosts the
carrier level to the power level set by the automatic power control. The carrier signal passes through the automatic
power control directional coupler, the RF output lowpass filter, and then is routed to the antenna connector.
Automatic Power Control
The automatic power control directional coupler samples a portion of the forward RF power output to determine the
RF level. Diode D15 rectifies this RF sample and produces a DC voltage which is proportional to the RF output
level. This DC signal is summed with the voltage set from the power output control RV3. This voltage is compared
with a voltage derived from the TX 8 volt supply and the difference is amplified by IC5. The output of the RF driver
is proportional to its supply voltage. This controls the DC output of Q9, which supplies Q12 and Q13 controlling the
output of Q14 over the range from 10 to 40 watts. This completes a negative feedback loop which results in constant
output power over supp ly vo l ta g e and temperature va riations.
FREQUENCY SYNTHESIZER
The phase locked loop (PLL) fr equency synthesizer sec tion is re spo nsibl e fo r generating the RF signal at the carrier
frequency during transmit and at the local oscillator frequency for the receiver during receive. A PLL functions by
comparing the output frequency of a voltage controlled oscillator (VCO) with a fixed frequency reference. An error
signal is generated which drives the control input of the voltage controlled oscillator to force its frequency to match
the reference. The PLL based frequency synthesizer has a digital fr equency divider inserted between the output of
the VCO and the frequency comparison circuitry. As this divider number is varied, the output frequency of the VCO
varies as well with a frequency step size equal to the reference frequency (6.25 kHz in this radio). This allows a large
range of frequencies to be generated with one well controlled oscillator signal, the reference.
PLL Integrated Circuit
IC118 contains most of the digital circuitry to form a PLL frequency synthesizer. This includes a reference
oscillator, programmable reference frequency divide r, a programmable variable frequency divider, a modulus con trol
Page-12-
Nov. 94
MONOGRAM SERIES LBI-38865
CIRCUIT ANALYSIS
counter, a phase/ fr equency comparato r an d a frequency lock dete c t or. The operation of this int egrated circuit is
controlled by the radio’s microprocessor through a serial data line.
Reference Oscillator
Crystal X2, varactor D122, a thermistor/resistor network and the oscillator stage of IC118 form a temperature
compensated 12.8 MHz oscillator. This frequency is divided by 2048 to generate the 6.25 kHz frequency for the PLL
frequency synthesizer. This reference determines the frequency stability of the overall radio.
Voltage Controlled Oscillator
Transistor Q115 and its associated circuitry form a voltage controlled oscillator which is voltage tuned and band
switched by varactor diodes D12 3 and D110. the VCO output is buffer ed and isolated by Q117, Q118 and Q119.
Audio modulation is applied to the cathodes of D123 and D110 to produce frequency modulation during transmit.
Dual Modulus Prescaler
The internal dividers within IC118 are not able to operate at the VCO output frequency. To alleviate this problem,
part of the overall frequency division necessary between the VCO and the phase/frequency comparator is placed
external to, and controlled by, IC118. IC117 divides the VCO frequency by 128 or 129, determined by the state of
IC118 pin 6. This produces a lowe r frequency which can be further divided by IC108. By strategic timing when to
divide by 128 or 129, the overall division will be that necessary to put the VCO on the correct frequency.
Loop Filter
Resistors R317 through R322 and capacitors C291, C294 and C295 form the loop filter. The purpose of the loop
filter is to filter out the 6.25 kHz reference frequency products from the output of phase/frequency comparator IC118
and to determine the dynamic operation of the overall loop.
R316, C289, Q113 and Q114 act to speed up operation of the synthesizer loop during channel changes and during
frequency transition (receive to transmit and transmit to receive).
Out-of-Lock Detector
IC118 contains a cir cu i t whi ch c om pa res the timing difference of the 6.25 kHz reference frequency and the divided
down VCO frequency. The output is a 6.25 kHz pulse whose duration is equal to the timing difference. R306 and
C274 filter this pulse and average it producing a DC voltage which is proportional to the pulse width. When the loop
is in lock, this voltage is zero, but when the loop is out of lock, it rises to a level which will forward bias Q112. The
output of Q112 drives the microprocessor. The microprocessor will not allow the radio to transmit unless the
synthesizer is in lock. This is to prevent out of band signals from being transmitted.
Page-13-
Nov. 94
MONOGRAM SERIES LBI-38865
PREVENTIVE MAINTENANCE
PREVENTIVE MAINTENANCE
To ensure high operating efficiency and to prevent mechanical and electrical failures from interrupting system
operations, routing checks should be made of all mechanical and electrical parts at regular intervals. Preventive
maintenance should include the following checks:
CONNECTIONS
Ground connections to the voltage source should be peri odically checked for tightness. Loose or poor connections to
the power source will cause excessive voltage drops and faulty operation. When ground connections are not made
directly to the batter, the connection from the battery to vehicle chassis must be checked for low impedance. A high
impedance may cause excessive voltage drops and alternat or noise problems.
ELECTRICAL SYSTEM
Check the voltage regulator and alternator or generator periodically to keep the electrical system within safe and
economical operation limits. Over voltage is indicated when the battery loses water rapidly. Usage of 1 or 2 ounces
of water per cell per week is acceptable for batteries in continuous operation. A weak battery will often cause
excessive noise or faulty operation.
MECHANICAL INSPECTION
Since mobile units are subject to constant shock and vibration, check for loose plugs, nuts, screws and other parts to
make sure that nothing is working loose.
ANTENNA
The antenna, antenna base and all contacts should be kept clean and free from corrosion. If the antenna or its base
should become coated or poorly grounded, loss of radiation and a weak signal will result.
ALIGNMENT
The transmitter and receiver meter readings should be checked periodically, and the alignment "touched up" when
necessary. Refer to the Alignment Procedure in this Service Manual.
FREQUENCY CHECK
Check the transmitter frequency and deviation. Normally, these checks are made when the unit is first put into
operation, after the first six months, and once a year thereafter.
Page-14-
Nov. 94
MONOGRAM SERIES LBI-38865
DISASSEMBLY
DISASSEMBLY
TOP AND BOTTOM COVERS
There are no screws used to secure the top and bottom covers. Both top and bottom covers are removed with a flat
blade screwdriver or similar tool. On each side of the radio there are t wo small slots (on e at the top and one at the
bottom). Insert the screwdriver into the slot and gently pry the lip of the cover out from the radio. without removing
the screwdriver from the slot and in the same motion, pry the cover up . Both covers can be rem ov ed f ro m eit h er side
of the radio.
FRONT PANEL
1. Remove the (6) M3 x 6 machine screws (3 on top and 3 on bottom) that secure the front panel to the chassis.
2. Two cables connect the volume board to the RF board (at PL1) and to the digital board at (PL2). These
cables may be unplugged at the RF boa rd and at the digital board. A ribbon cable from the di splay board to
the digital board must be unplugged to remove front panel.
RF BOAR D
1. Remove the (13) M3 x 24 machines screws securing the RF shield to the chassis.
2. Remove the M3 x 8 machine screw that secures the DC cord bracket to the chassis. Slide the bracket and
cord out of the chassis.
3. Remove the (6) M3 x 6 machine screws (3 on top and 3 on bottom) that secure the front panel to the chassis.
4. Remove the RF shield by pushing the front panel forward so the shield will clear and then sliding the DC
cord, bracket and connector through the rectangular hole in the shield.
5. De-solder the antenna connector from the RF board.
6. Remove the remaining (10) machine screws securing RF board, IC1, and Q14 and Q9.
7. Q13 is mounted to the chassis with a spanner nut which is only accessible from top of the radio through a
hole in the digital board. Remove the spanner nut.
8. Remove the RF board.
Page-15-
Nov. 94
MONOGRAM SERIES LBI-38865
DISASSEMBLY
DIGITAL BOARD
1. Remove the (6) M3 x 18 machine screws that secure the top panel shield to the chassis.
2. Unplug and remove the Auxiliary Relay PCB at PL5.
3. Remove the (6) machine screws (3 on top and 3 on bottom) that secure the front panel to the chassis.
• The following steps detail the removal of the RF shield which is necessary before continuing with the removal
of the digital board.
4. Remove the (13) M3 x 24 machine screws securing the RF shield to the chassis.
5. Remove the M3 x 8 machine screw that secure the DC cord bracket to the chassis. Slide the bracket and
cord out of the chassis.
6. Remove the RF shield by pushing the front panel forward so the shield will clear and then sliding the DC
cord, bracket and connector through the rectangular hole in the shield.
7. Unplug the VCO cable from the jack.
8. Remove the remaining (10) screws securing the digital board, IC5, IC6 and IC104 to the chassis.
9. The digital board can now be removed from the chassis, however the front panel assembly is still attached b y
two cables (on e fr om th e Cont rol boar d and one from t he displ ay b oard ). T he cable from the Control board at PL2
may be unplugged. The ribbon cable from digital board may be unplugged at FLT.
Page-16-
Nov. 94
MONOGRAM SERIES LBI-38865
PROGRAMMING INSTRUCTION
PROGRAMMING INSTRUCTION
The UHF synthesized mobile radio is equipped with a personality EEPROM. All customer information such as the
customer frequencies, custome r tones and customer options are stored in the EEPROM. The EEPROM cont ains all
information to tailor the operation of the radio to the user’s requirements. The EEPROM is programmed by using an
IBM compatible pers on al co mp ut er with MSDOS, Programming Cable TQ-3376 and Pro gr amming software
TQ-3375.
PROGRAMMING THE RADIO
The Programming Ca ble TQ-3376 is a Y-cable . The base of the "Y" has a standard 25 pin connector whic h pl u gs
into the computer, the remaining end has a 6 pin connector which fits into the connector PL1 on the digital board
inside the radio. To use this cable, remove the top cover of the radio as described in the DISASSEMBLY section.
Plug the six pin connector into the socket inside the radio (PL1), which is located near the EEPROM IC107. Plug the
base of the "Y" into the computer that will program the radio. See the diagram in TQ-3375 Software Manual. In
order to program the radio with the programming cable, it is necessary to put the radio into the programming mode.
To do this, press the P "PRIORITY" button/LED on the radio and turn the radio ON. The radio will sound a prompt
tone and show the words "PROG" on the display. Please refer to the Software Manu al fo r fu rther instructions on the
operation of the Programming Software. After completing the programming instructions in the Manual, remove the
cable from PL1 and replace the cover on your UHF synthesized mobile radio.
Page-17-
Nov. 94
MONOGRAM SERIES LBI-38865
TEST EQUIPMENT SETUP
TEST EQUIPMENT SETUP
*
Page-18-
Nov. 94
*
* = OPTIONAL TEST EQ.
MONOGRAM SERIES LBI-38865
ALIGNMENT PROCEDURE
ALIGNMENT PROCEDURE
SUGGESTED TEST EQUIPMENT
• WARNING: Any repairs or adjustments should be made under the supervision of a certified technician.
The following equipment, or its equivalent, is required for proper alignment of the UHF synthesized mobile radio:
1. Termaline watt meter or Through-line watt meter with termination into 50 ohm dummy load.
2. AC/DC VOM with a minimum of 1 Megohm input impedance.
3. SINAD Meter.
4. FM Communications Monitor.
5. Regulated power supply capable of 9 to 16 volts adjustable; at least 10 ampere capability.
6. Oscilloscope.
7. Audio Distortion Meter (desirable but not necessary).
8. Frequency Counter.
PROGRAMMING FOR ALIGNMENT
For the alignment procedures the EEPROM should be programmed as follows:
1. An EEPROM should be programmed with 3 transmit and 3 receive frequencies.
2. The lowest and hig h est frequencies shou ld enclose the user’s frequencies and be 10 MHz apart. The lowest
and highest frequencies mu st be within the appropriate frequency band.
3. In addition to programming frequencies, CTCSS and DCS codes must also be programmed to insure that
the modulation deviation for these potential options is correct, even if they are not to be used for the
customer’s operation. The following format should be used:
Lowest RX/TX frequency 67.0Hz CTCSS Tone
Middle RX/TX frequency DCS Code 072
Highest RX/TX freque ncy 250.3Hz CTCSS Tone
Highest RX/TX frequency No Tone Options
Page-19-
Nov. 94
MONOGRAM SERIES LBI-38865
ALIGNMENT PROCEDURE
4. The middle RX/TX frequencies should be halfway between the lowest and the highest frequencies.
• NOTE: There should be 4 channels programmed with a total of 3 different frequencies.
5. The highest transmit frequency can typically be only 10 MHz above the lowest receiver frequency.
PLL ALIGNMENT
1. Connect an RF dummy load or power attenuator (50 watt minimum rating) to the antenna receptacle.
2. Connect a VOM or DVM to TP1, accessed through a hole in the VCO cover.
3. Set the CHANNEL selector to the lowest receive frequency.
4.
Adjust TC13 setting the voltage measured at TP1 to 1.5 volts (±.05).
5. Change the CHANNEL selector to the highest transm it fre quen cy .
6. Press the PTT switch. The VOM should read less than 7.5 volts.
7. Release the PTT switch.
TP1 VOLTAGE
CHANNEL
TRANSMIT RECEIVE
Lowest Frequency 1.5 VDC 2.0 VDC
Highest Frequency 7.5 VDC 7.0 VDC
TRANSMITTER ALIGNMENT
1. Connect a 50 ohm RF dummy load or a power attenuator (50 watt minimum rating) through a watt meter
(50 watt scale) to the antenna receptacle.
2. Turn RV2 (Automatic power adjustment) fully clockwise.
3. Connect variable DC power supply (10 Ampere capability) to the DC power cable on the radio. Set the
voltage to 13.8 VDC measured at the radio during transmit. (Voltage drops in the power cable during
transmit will lower the voltage at the radio).
4. Set the CHANNEL selector to a mid-frequency transmit channel.
5. Press the PTT switch.
• NOTE: The power ou tput may exceed 50 w atts.
6. Adjust RV2 for 40 watts, or the desired power output. (10 - 40 watts). Release the PTT switch.
Page-20-
Nov. 94
MONOGRAM SERIES LBI-38865
ALIGNMENT PROCEDURE
• WARNING: To prevent damage to the radio, avoid keying the radio for pe riods long er than 1 m inute. Allo w a
5 minute cool down pe ri od aft er keying the radio for 1 min u te.
7. Check the power output at the lowest, middle and highest transmit channels and adjust RV2 if necessary, to
maintain 40 watts at all frequencies.
8. Press PTT and adjust TC11 for the correct frequency.
DCS Modulation Balance Adjustment
1. Connect test equipment to the radio as shown in the Test Equipment Setup.
2. Set the CHANNEL selector to a transmit channel which has a DCS code pre-programmed (should be
mid-frequency ch annel).
• WARNING: The power attenuator must have enough attenuation to prevent damage to the deviation meter.
3. Press the PTT switch.
4. Observe the waveform on the oscilloscope and compare with that shown in Figure 6.
5. Adjust RV5 and TC12 to achieve the proper wave form. Release the PTT switch.
DCS Modulation Wave Form
6. Replace the de vi ation meter with a freq uency counter.
7. Set the CHANNEL selector to the highest transmit channel. Ensure that this channel has no DCS or CTCSS
tones pre-programmed.
8. Press PTT switch. Adjust TC11 for the correct transmit frequency. Release the PTT.
• NOTE: TC12 should not be allowed to be placed at the maximum capacitance position, if TC12 should be found
to be at the maximum capacitance position, place TC12 at the typical position and adjust RV5 for the proper
wave form.
30°
TC12 Maximum capacitance position and typical position
Page-21-
Nov. 94
MONOGRAM SERIES LBI-38865
ALIGNMENT PROCEDURE
Modulation Deviation Adjustment
1. Connect an RF deviation meter to the radio through a power attenuator.
2. Set the CHANNEL selector to a transmit channel which has a DCS code pre-programmed (should be a
mid-frequency ch annel).
3. Press the PTT switch.
4. Adjust RV3 for proper deviation, typically 750Hz. Release the PTT switch.
5. Set the CHANNEL selector to a transmit channel which has a low-frequency CTCSS tone (67.0Hz)
pre-programmed.
6. Press the PTT switch and verify that the deviation is between 500Hz and 1000Hz. Release the PTT switch.
7. Set the CHANNEL selector to a transmit channel which has a high-frequency CTCSS tone (250.3Hz)
pre-programmed.
8. Press the PTT switch and verify that the deviation is between 500Hz and 1000Hz. Release the PTT switch.
a. If deviation level is not that obtained in Step 6 adjust RV 401 to same level.
9. Connect an audio frequency generator to the MIC input (connected to the white wire in the microphone
cable) of the radio. Set the audio output level for 30 mV. the audio frequency should be 1 kHz.
10. Press the PTT switch.
11. Adjust RV4 (maximum deviation adjustment) for the 4.2 kHz deviation if no CTCSS tones are present, and
4.9 kHz deviation i f CTCSS tones are pres ent.
RECEIVER ALIGNMENT
1. Connect an RF signal generator or communications service monitor to the antenna receptacle.
2. Connect a SINAD meter and an audio distortion an aly ze r ac ro ss the speaker terminals. If an audio
distortion analyzer is not available, connect an oscilloscope across the speaker terminals.
3. Turn the SQUELCH control fully counter-clockwise.
4. Adjust the VOLUME control to the proper level for the SINAD meter and audio distortion analyzer.
5. Set the CHANNEL selector to a mid-frequency receive channel.
6. Tune the RF signal generator to the channel frequency. the RF output level should be set for -47 dBm. The
modulation should be set for ±3 kHz FM deviation of a 1 kHz tone.
7. Adjust T10 for maximum audio output. Readjust the VOLUME control if necessary to avoid clipping on
the output audio wave form. (This adjustment is typically not required.)
8. Decrease the RF generator output and adjust T1 through T9 for maximum sensitivity.
9. Check the sensitivity at the lowest and highest receive frequencies. If necessary, repeat steps (8) and (9)
above at the lowest middle and highest frequencies for the best overall sensitivity.
Page-22-
Nov. 94
MONOGRAM SERIES LBI-38865
ALIGNMENT PROCEDURE
Receiver Squelch Adjustment
1. Set the channel selector for the mid frequency receive channel.
2. Connect an RF signal generator or communications service monitor to the antenna receptacle. The
modulation should be set fot ±3 kHz FM modulation of a 1kHz tone. The RF output level should be at a
minimum.
3. Adjust the SQUELCH control to the threshold point (the point where the speaker audio disappears).
4. Increase the RF signal generator output level until speaker audio output reappears. Note the generator level.
5. Turn the SQUELCH control fully clockwise.
6. Increase the RF signal generator level by 16 dB.
• NOTE: This squelch adjustment procedure is very important for the correct operation of the microprocessor
aided squelch system.
Page-23-
Nov. 94
MONOGRAM SERIES LBI-38865
RF BOARD ALIGNMENT AND TEST POINTS
RF BOARD ALIGNMENT AND TEST POINTS
Page-24-
Nov. 94
MONOGRAM SERIES LBI-38865
DIGITAL BOARD ALIGNMENT AND TEST POINTS
DIGITAL BOARD ALIGNMENT AND TEST POINTS
Page-25-
Nov. 94
MONOGRAM SERIES LBI-38865
PERFORMANCE TEST
PERFORMANCE TEST
TRANSMITTER PERFORMANCE TEST
Power Output
1. Set the power supply voltage to 13.8 VDC (measured at the radio during transmit).
2. Connect an RF watt meter and dummy load to the antenna receptacle.
3. Press the PTT switch.
4. Verify that the output is at least 40 watts.
5. Reduce the power supply voltage to 11 volts.
6. Verify that the output is at least 15 watts.
7. Release the PTT switch.
Audio Response
1. Connect an audio generator to the microphone jack on the radio. Set the generator for a frequency of 1 kHz.
2. Connect a communication service monitor to the RF output of the radio through a power attenuator. Set the
monitor to read average peak FM deviation.
3. Press the PTT switch.
4. Adjust the audio generator level to produce 1 kHz deviation.
5. Set the audio generator frequency to 2 kHz. The transmitter deviation should be approximately 2 kHz.
6. As the audio generator frequency is varied from 300Hz to 10 kHz, the deviation should increase until it
reaches a maximu m at an a ud io frequency of 2.5 kHz to 2. 9 kHz. At higher frequenci es, the deviation
should decrease. the deviation at an audio frequency of 6 kHz should be less than 1 kHz.
7. Release the PTT switch.
Limiting Test
1. Set the audio generator frequenc y to 1 kH z.
2. Press the PTT switch and adjust the generator level to produce 1 kHz deviation. Note the generator level.
3. Increase the audio generator level by 20 dB (factor of 10 times).
4. Sweep the audio generator over a freque ncy range of 300Hz to 3 kHz. the deviation should not ex ce ed
±1kHz within this range.
5. Release the PTT switch.
Page-26-
Nov. 94
MONOGRAM SERIES LBI-38865
PERFORMANCE TEST
Spectrum Test
1. Connect a spectrum analyzer to a sampled RF output of the radio.
2. Press the PTT switch. Observe the output spectrum on the spectrum analyzer.
3. All spurious and harmonics should be at least 60 dB below the carrier level.
4. Release the PTT switch.
RECEIVER PERFORMANCE TESTS
SINAD Sensitivity
1. Connect the FM signal generator of communication service monitor to the antenna jack.
2. Connect a SINAD meter across the speaker leads.
3. Turn the SQUELCH control fully counterclockwise for maximum noise.
4. Adjust the VOLUME control to approximately mid-range.
5. Set the FM signal generator or service monitor to the receive frequency. The modulation should be set for 3
kHz deviation of a 1 kHz tone.
6. Adjust the generator RF level so that the SINAD meter reads 12 dB. The signal generator RF level should
be .35 uV or less.
Noise Quieting Sensitivity
1. Connect a VOM to the speaker leads.
2. Turn the SQUELCH control fully counterclockwise for maximum noise.
3. With no RF signal generator or communication service monitor connected to the radio, adjust the
VOLUME control to obtain a noise reading of 1 volt RMS on the VOM.
4. Connect the RF signal generator or service monitor to the radio. Set the RF frequency to the receiver
frequency of radio and remove any modulation.
5. Adjust the signal generator RF level for a noise reading on the VOM of 0.1 volt RMS. This is the 20 dB
noise quieting point. the RF level should be 0.5 uV or less.
Squelch Sensitivity
1. Set the RF signal generator or service monitor to the receive frequency. Set the modulation to 3 kHz
deviation of a 1 kHz aud i o t on e .
2. Reduce the signal generator RF output to ze ro .
3. Rotate the SQUELCH control clockwise to the point where the speaker noise just goes away.
4. Increase the signal generator or service monitor RF level until the speaker noise returns. This is the
threshold squelch setting. The generator output level should not exceed 0.20 uV.
5. Turn the SQUELCH control to maximum clockwise rotation.
6. Increase the generator output level until the squelch opens (busy LED is on). The output level should be
between 10 and 20 dB (3 to 10 times) above the threshold setting.
Page-27-
Nov. 94
MONOGRAM SERIES LBI-38865
PERFORMANCE TEST
Audio Output
1. Increase the RF signal generator or service monitor RF level to 1000 uV.
2. Connect a 4 ohm audio dummy load to the AUXILIARY speaker jack.
3. Connect a true RMS audio voltmeter (the audio distortion analyzer may include this function) to the
speaker leads.
4. With a 3 kHz deviation of a 1 kHz tone modulation applied to the signal generator, rotate the VOLUME
control clockwise until the audio distortion is 10% or until the VOLUME controls reaches stop, whichever
comes first.
5. The audio voltmeter s ho uld r ead 4.0 volts or greater.
Page-28-
Nov. 94
MONOGRAM SERIES LBI-38865
COMPONENT REPLACEMENT
COMPONENT REPLACEMENT
SURF ACE MOUNT COMPONENTS
Surface mount components should always be replaced using a temperature controlled soldering system. The
soldering tools may be either a temperature controlled soldering iron or a temperature controlled hot-air soldering
station. A hot-air system is recommended for the removal of components on the multi-layered boards used in the
UHF synthesized mobile radio. With either soldering system, a temperature of 700°F (371°C) should be maintained.
The following procedures outline the removal and replacement of surface mount components. If a hot-air soldering
system is employed, see the manufacture’s operating instructions for detailed information on the use of your system.
• CAUTION: Avoid applying heat to the body of any surface mount component using standard soldering methods.
Heat should be applied only to the metallized terminals of the components. Hot-air systems do not damage the
components since the heat is quickly and evenly distributed to the external surface of the component.
• CAUTION: The CMOS Integrated Circuit devices used in this equipment can be destroyed by static discharges.
Before handling one of these devices, service technicians should discharge themselve s by touching the c ase of a
bench test instrument that has a 3-prong power cord connecte d to an outlet with an known good earth ground.
When soldering or desoldering a CMOS device, the soldering equipment should have a known good earth ground.
SURF ACE MOUNT REMOVAL
1. Grip the component with tweezers or small needle nose pliers.
2. Alternately heat the metallized terminal ends of the surface mount component with the soldering iron. If a
hot-air system is used, direct the heat to the terminals of the component. Use extreme care with the
soldering equipment to prevent damage to the printed circuit board (PCB) and the surrounding components.
3. When the solder on all terminals is liquefied, gently remove the component. Excessive force may cause the
PCB pads to separate from the board if all solder is not completely liquefied.
4. It may be necessary to remove excess solder using a vacuum de-soldering tool or Solder wick. Again, use
great care when de-soldering on the printed circuit boards. it may also be necessary to remove the epoxy
adhesive that was un de r t he surface mount compo ne nt an d an y fl u x on th e pr i nted circuit board.
SURF ACE MOUNT COMPONENT REPLACEMENT
1. "Tin" one terminal end of the new component and the corresponding pad of the PCB. Use as little solder as
possible.
2. Place the component on the PCB pads, observing proper orientation for capacitors, diodes, transistors, etc.
3. Simultaneously touch the "tinned" terminal end and the "tinned" pad with the soldering iron. Slightly press
the component down on the board as the solder liquefies. Solder all terminals, allowing the component time
to cool between each app l i cation of heat. Do not apply he a t for a n ex cessive length of tim e an d do not us e
excessive solder. With a hot-air system, apply hot air until all "tinned" areas are melted and the component
is seated in place. It may be necessary to slightly press the component down on the board. Touch-up the
soldered connections with a standard soldering iron if needed. do not use excessive solder.
4. Allow the component and the board to cool and then remove all flux from the area using alcohol or another
approved flux remover.
Page-29-
Nov. 94
MONOGRAM SERIES LBI-38865
COMPONENT REPLACEMENT
SURF ACE MOUNTED INTEGRATED CIRCUIT REPLACEMENT
• CAUTION: Some chemicals may damage the internal and external plastic parts of the radio.
Soldering and de-soldering techniques of the surface mounted IC’s are similar to the above outlined procedures for
the surface mounted chip components. Use extreme care and ob serve static precauti o ns when removing or replacing
the defective (or suspect) IC’s. this will prevent any damage to the printed circuit board or the surrounding circuitry.
The hot-air soldering system is the best method of replacing surface mount IC’s can easily be removed and installed
using the hot-air system. See the manufacturers instructions for complete details on tip selection and other operating
instructions unique to your system.
If a hot-air system is not available, the service technician may wish to clip the pins near the body of the defective IC
and remove it. the pins can then be removed from the PCB with a standard soldering iron and tweezers, and the new
IC installed following the Surface Mount Component Replacement procedures. It may not be necessary to "tin" all
(or any) of the IC pins before the installation process.
Page-30-
Nov. 94
ELECTRICAL PARTS LIST
NOTE
Only those items indicated by shading will be stocked by After Market
Services. All other items are fo r reference only.
When ordering parts for your Monogram Series radio, precede all part numbers
with the prefix "R29/"
Page-31-
Nov. 94
Page-31.1
Page-31.2
Page-31.3
Page-31.4
Page-31.5
Page-31.6
Page-31.7
Page-31.8
Page-31.9
Page-31.10
Page-31.11
Page-31.12
Page-31.13
Page-31.14
Page-31.15
Page-31.16
Page-31.17
PRINTED CIRCUIT BOARD LAYOUT
Page-32-
Nov. 94
MONOGRAM SERIES LBI-38865
TOP VIEW 406136-E RF BOARD
TOP VIEW 406136-E RF BOARD
Page -32.1-
Nov. 94
MONOGRAM SERIES LBI-38865
BOTTOM VIEW 406136-E RF BOARD
BOTTOM VIEW 406136-E RF BOARD
Page -32.2-
Nov. 94
MONOGRAM SERIES LBI-38865
TOP VIEW 406137-E DIGITAL BOARD
TOP VI EW 406137-E DIGITAL BOARD
Page -32.3-
Nov. 94
MONOGRAM SERIES LBI-38865
BOTTOM VIEW 406137-E DIGITAL BOARD
BOTTOM VIEW 406137-E DIGITAL BOARD
Page -32.4-
Nov. 94
MONOGRAM SERIES LBI-38865
MISC. PRINTED CIRCUIT BOARDS
MISC. PRINTED CIRCUIT BOARDS
DISPLAY BOARD TOP VIEW
DISPLAY BOARD BOTTOM VIEW
VOLUME BOARD BOTTOM VIEWVOLUME BOARD TOP VIEW
Page -32.5-
Nov. 94
MONOGRAM SERIES LBI-38865
MISC. PRINTED CIRCUIT BOARDS
MISC. PRINTED CIRCUIT BOARDS
406-969-F (DIG. PCB) TOP
406-968-C (RF. PCB) TOP 406-968-C (RF. PCB) BOTTOM
406-969-F (DIG. PCB) BOTTOM
406-973-A TOP
406-973-A BOTTOM
Page -32.6-
Nov. 94
MONOGRAM SERIES LBI-38865
VOLTAGE CHARTS
VOLTAGE CHARTS
Page -32.7-
Nov. 94
MONOGRAM SERIES LBI-38865
VOLTAGE CHARTS
VOLTAGE CHARTS
Page -32.8-
Nov. 94
MONOGRAM SERIES LBI-38865
VOLTAGE CHARTS
VOLTAGE CHARTS
Page -32.9-
Nov. 94
MONOGRAM SERIES LBI-38865
VOLTAGE CHARTS
Page -32.10-
Nov. 94
EXPLODED VIEW
AND
EXPLODED VIEW PARTS LIST
NOTE
Only those items indicated by shading will be stocked by After Market
Services. All other items are fo r reference only.
When ordering parts for your Monogram Series radio, precede all part numbers
with the prefix "R29/"
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Nov. 94
MONOGRAM SERIES LBI-38865
Page -33.1-
Nov. 94
MONOGRAM SERIES LBI-38865
Page -33.2-
Nov. 94
MONOGRAM SERIES LBI-38865
Page -33.3-
Nov. 94
SCHEMATICS
Ericsson Inc.
Private Radio Systems
Mountain View Road
Lynchburg,Virginia 24 502
1-800-528-77 11 (Outside USA, 804-528-7711)
Printed in U.S.A.
Page-34-
Nov. 94
LBI-38865
RF BOARD
R29/406136-E
34.1
LBI-38865
DIGITAL BOARD
R29/406137-E
34.2
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