Introduction; Notes For All Schematics And Circuit Boards - Motorola HT1250-LS+ Service Manual

Chapter 5
Schematic Diagrams, Overlays, and Parts Lists
5.1

Introduction

This chapter provides schematic diagrams, overlays, and parts lists for the radio circuit boards and
interface connections.
5.1.1

Notes For All Schematics and Circuit Boards

* Component is frequency sensitive. Refer to the Electrical Parts 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 point indicated to chassis ground using a Motorola DC multime-
ter or equivalent. Transmitter measurements should be made with a 1.2 µH choke in series with
the voltage probe to prevent circuit loading.
3. Reference Designators are assigned in the following manner:
Circuit Block
Receiver Front End
Receiver I-F
Frequency Sysnthesizer
VCO's
Transmitter and Power Control
Microprocessor
Memory
RX Audio Opamp Gain Stage
ASFIC
Audio Power Amplifier
Controls and Indicators
Keypad/PassPort Board Interface
Keypoad/PassPort Option Board
4. Interconnect Tie Point Legend:
CLK = Clock
CSX = Chip Select Line
MECH_SWB+ or SWB+ = Switched Battery Voltage (7.5V)
R5 = Receive Mode 5 V
SYN = Synthesizer
T5 = Transmit Mode 5V
UNSWB+ = Unswitched Battery Voltage (7.5V)
Vdda = Regulated 3.3 Volts (for analog)
Vddd = Regulated 3.3 Volts (for digital)
VSF = Super Filtered (4.5 V)
Series (200 MHz)
3300
3100-3200
3700
3800
3500
400
400
600, 2000
400
400
500
400, 4000
600
Series (700 MHz)
300
350
200
600
100
400
400
850
400
400
500
400, 500
600
5-1