QM-790 Professional Mobile Radio Service Manual (V03 PDF)

Description

QM-790 Professional Mobile Radio Service Manual (V03 PDF) DOWNLOAD

Description

The QM-790 Professional Mobile Radio Service Manual (V03) is the complete factory engineering document used by certified radio technicians for maintenance, calibration, programming, circuit-level diagnosis, and component-level repair of QM-790 mobile radios.
This extensive manual covers radio operation, software specifications, tuning modes, component descriptions, and full electronic schematics — essential for professional bench technicians.

Table of Contents

1. Revision History

• Version changes & PCB details

2. General

• Manual Scope

• Safety Standards

• Installation Guidelines

• Operation Safety Notes

3. Radio Overview

• Front Panel Layout

• Rear Panel Connections

• LCD Display Icons

• Programmable Function Keys

• LED Indicator behavior

4. Software Specifications

• Radio Modes

• User Mode

• Model Set Mode

• Panel Tuning Mode

• Clone Mode (Dealer / Factory)

• Firmware Version Display Mode

• PC Programming Mode

5. Circuit Description

• Frequency Configuration

• Receiver Circuit (Superheterodyne, IF stages)

• Transmitter Circuit

• VCO & PLL Control

• Audio/Squelch circuitry

• Power Supply

• Control Circuit

• Display Circuit

6. MCU Pin Function

• Complete CPU pin-level mapping (100 pins)

• Interface Signals

• GPIO functions

7. Terminal Functions

• Display Unit Pin Map

• Tx/Rx Unit Pin Map

• External PTT, Mic, GPS, AUX inputs

• Speaker, power & data interfaces

8. Tuning Description

• Panel Tuning Mode

• Complete step-by-step tuning operations

• Tx High/Low power tuning

• Wide/Medium/Narrow deviation tables

• CTCSS / CDCSS deviation tuning

• DTMF / MSK deviation

• Squelch tuning (Open/Close Level 3/9)

• Sensitivity alignment

• Tuning flow charts

9. Troubleshooting Flow Chart

• Power-On Failure

• No Transmit Output

• No Receive

• VCO lock issues

• Audio failures

• PA failures

10. Disassembly & Assembly

• Removing chassis

• Front panel removal

• PCB separation

• PA module removal

• Reassembly sequence

11. Exploded View & Mechanical Parts List

• Full mechanical drawing

• Part numbers (knobs, chassis, LCD, keys, PA module, screws, etc.)

12. PCB Views

• QM-790-U Main PCB (Top/Bottom)

• QM-790-V Main PCB (Top/Bottom)

• VCO PCB (Top/Bottom)

• Display PCB (Top/Bottom)

13. Electronic Parts List

• All capacitors, ICs, transistors, resistors

• RF components

• VCO components

• Audio & control parts

• Power circuitry parts

• Fully indexed by reference number

14. Block Diagram

• Radio system architecture

15. Schematic Diagrams

• Complete circuit schematics for entire radio system

16. Specifications

• RF performance

• Audio characteristics

• Power consumption

• Electrical ranges

📑 File Details