Midland 70-050 User manual

iilDLAND ©VINl^rHOlH]
VHF (LOW BAND)
SERVICE MANUAL
70-050
70-055
1690 North Topping Avenue
Kansas City, Missouri 64120 70-300500
09-050055-SM-3/85-1M

70-050/055
The Midland Models 70-050A, 70-050B, 7 0 - 0 5 ° C ’
7n D55C are solid state VHF Low Band Land Mobile
“ opera e the 29-37 MHz (7O-05OA, 70-055A)
70-053b 5 and 40-54 MHz (70-050C, 70-0550 ranges
70-05 5A, 70-055B, and
transceivers designed
35_44 MHz (70-050B,
and field
programmable/
these S'YN-TECH
Providino up to 80 channel capability
rroviu-Lug f r . 1P n r ies and options,
models^are^esignet/lc/providt^flexible c.Snlc.t* on. .or a vartet,
of applications.
distributed in the following forms.
service
; h e d and
Manual Addition (MA)
Change
Notice (CN)
Provides additional information useful
in unit alignment and service or to
upgrade for increased capability,. rrm
ted on BLUE paper.
rcuitry changes made during
by model and serial number.
YELLOW paper.
Details
production
Printed on
Manual Correction (MC)
Corrects manual errorsnot related to
production changes. Printed on
paper.
— , . . nii t i n (TB)- Provides solutions for field problems
fechmcal Bulletin ( ) ^ Lips for performance improvement.
. n T 11 1/ _ „ ~ ~
Careful use of
installed and
areas of manual
the manual information wilJ
maintained units. Comments
improvement are welcome.
insure properly aligned,
or suggestions conceining

TABLE OF CONTENTS
70-050/055
INTRODUCTION . P a 8 e 2
TABLE OF CONTENTS . p age 3
SPECIFICATIONS
General.P a 8 e 4
Receiver Performance.page 5
Transmitter Performance and CTCSS . page 6
E/PROM PROGRAMMING . p ages 7,8,9
THEORY OF OPERATION . pages 10,11,12,13,14
BLOCK DIAGRAM . P a 8 e 15
SUGGESTED TEST INSTRUMENTS . p age 16
Test Equipment Set-Up Diagrams.page 16
ALIGNMENT INSTRUCTIONS . p ages 17,18
Receiver & PA Board Alignment Points Diagram.page 19
Transmitter Alignment Points Diagram.page 20
Supplemental Alignment Instructions.page 21
PC BOARDS
E/Prom (Top & Bottom), Display CX-03 (Top & Bottom).page 22
Control CX-04, Control Interface CX-05 (Top 6 Bottom).page 23
Display Driver CX-06 (Top & Bottom)...page 23
Display CX-07 (Top & Bottom), Control Cable CX-08.page 24
CONTROL HEAD SCHEMATIC DIAGRAM 70-055A,B,C . p age 25
CONTROL INTERFACE SCHEMATIC DIAGRAM 70-055A.B.C . p age 26
CONTROL PANEL SCHEMATIC DIAGRAM 70-050A,B,C . p age 27
PC BOARD INTER-CONNECT DIAGRAMS
70-050A/B/C.P a S e 28
70-055A/B/C.Page 29
RECEIVER PC BOARD DRAWINGS
70-050/055 (Top View).page 31
70-050/055 (Bottom View).page 32
RECEIVER SCHEMATIC DIAGRAMS
70-050A/B/C.page 33
70-055A/B/C.. 34
TRANSMITTER PC BOARD DRAWINGS
70-050/055 (Top View). P age 35
70-050/055 (Bottom View).page 36
PA PC BOARD DRAWINGS
70-050/055 (Top View).page 37
70-050/055 (Bottom View).page 38
TRANSMITTER SCHEMATIC DIAGRAM . p age 39
VOLTAGE CHARTS
Transistors.page 40
Transistors, F.E.T.'S, Digital IC.page 40
Analog IC 6, IC901 Pin Out.page 41
SIMPLIFIED SQUELCH CIRCUIT SCHEMATIC . p age 42
REPAIR INFORMATION
Chip Component Identification Removal, Replacement.page 43
IC Removal, Replacement.page 44
PC Board Removal.page 45
TROUBLE SHOOTING CHARTS
General .
Receiver.
Transmitter, Modulator.
CPU/PLL . .
MOBILE INSTALLATION DIAGRAMS
70-050..
70-055.
INSTALLATION INSTRUCTIONS .
NOISE SUPPRESSION .
ACCESSORIES .
UNDER DASH DC POWER/ACCESSORY PLUG INSTRUCTIONS .
TRUNK MOUNT DC POWER/ACCESSORY PLUG INSTRUCTIONS .
MICROPHONE HANG-UP BOX & PARTS LIST .
MICROPHONE SCHEMATIC & PARTS LIST .
EXPLODED MECHANICAL VIEW DRAWINGS
70-050.
70-055.
PARTS LIST . p ages
PARTS ORDERING INFORMATION .
APPENDIX - OPTION INFORMATION
CTCSS Board, Model 70-2102A .
2/2.5 PPM Oscillator Kits, Models 70-2124/2125.
12.5 KHz Channel Spacing Kit, Model 70-2132 . .
Scan Kit (UD), Model 70-2141.
Scan Kit (TM), Model 70-2142.
Two Tone Sequential Decoder, Models 70-2151/2152
Noise Blanker Kit, Model 70-2191.
Tone Enabled Transmit/Receive .
Base Station Mic Adaptor Kit, Model 70-K33. . .
Special Busy Channel Lock-Out .
.page 47
.page 48
.page 49
.page 50
.page 51
.page 52
.pages 53,54
.pages 55,56
.page 57
.page 58
.page 59
.page 60
.page 61
.page 63
.page 64
65,66,67,68,69,70,71,72,73,74,75,76
.page 77
. . .pages 79,80,81,82,83,84,85,86
.page 87
.pages 88,89
.page 90
.page 91
.pages 92 thru 102
.pages 103,104
. page 105
. page 106
.pages 107,108
3

GENERAL SPECIFICATIONS 70-050/055
Nominal operating voltage:
Temperature range:
Antenna impedance:
Microphone:
Speaker - internal:(70-050A/050B/050C)
external:
Frequency control:
Frequencies of operation:
Receiver and transmitter performance
bandwidth without adjustment:
Maximum transmit-to-receive
frequency separation:
Frequency tolerance and stability:
Duty cycle:
High humidity:
Vibration stability:
Shock stability:
Channel capability:
Current drain - Standby:
Receive:
Transmit:
Dimensions (HWD):
Main chassis: (70-050/055)
Control head: (70-055)
Speaker: (70-055)
Weight:
Main chassis: (70-050/055)
Control Head: (70-055)
Speaker: (70-055)
13.6V DC (negative ground)
(12.2-16V DC range)
-30°C to +60°C
50 ohms, unbalanced
Dynamic element, with amplifier
8 ohms
4 ohms
Frequency synthesized with
EPROM Programming
29-37 MHz (70-050A/055A)
35-44 MHz (70-050B/055B)
40-54 MHz (70-050C/055C)
1.0 MHz Standard
2.0 MHz (Optional)
2.0 MHz
+5 PPM Tx and Rx (Standard)
+2.5 or 2.0 PPM Tx and Rx (Optional)
Intermittent EIA RS 152-B
(1 minute Tx, 4 minutes Rx)
95% @ 50°C per EIA
RS-152-B, sec. 13
EIA RS-152-B, sec. 14
EIA RS-152-B, sec. 15
Up to 80 channel transmit/receive
0.35 A DC
1.00 A DC
8.00 A DC
65 x 185 x 280mm (2% M x 7V x 11")
50 x 88 x 80mm (2" x 3%" x 3 3/16")
100 x 100 x 77mm (4" x 4" x 3")
3.0 kg (6.6 lb.)
0.8 kg (1.8 lb.)
0.71 kg (1.58 lb.)
4

RECEIVER SPECIFICATIONS
70-050/055
Refer to EIA RS-204-C and
Standard of Performance.
Sensitivity:
Squelch sensitivity:
DOC RSS-119 for Method of
12dB SINAD
Threshold
Tight
Measurement and
0.25uV @50 ohm
0.2uV max or 6dB
SINAD
1.OuV min, 2.OuV max
Squelch blocking:
Receiver attack (squelch release)
time:
Receiver squelch closing time:
Modulation acceptance bandwidth:
lOdB
100ms max
200ms max
+7.0KHz min @ 20/25/30 KHz
+4.5KHz min @ 12.5 KHz
Adjacent channel two signal
selectivity and desensitization:
Spurious response attenuation:
Intermodulation spurious response
attenuation:
(measured at useable sensitivity)
Audio power output:
Audio frequency response:
Hum and noise:
Conducted suprious RF power:
90dB @ +20KHz
90dB
80dB (Noise Blanker off)
75dB (Noise Blanker on)
1W @ 5°6 THD @ 8 ohms (Internal)
5W a 5°o TI1D @ 3.2 ohms (External)
Per EIA and DOC Specifications
Unsquelched 40dB
Squelched 50dB
200uV across 50 ohms (800pW)
from DC to 1000MHz
Intermediate Frequencies: 10.7MHz (1st) and 455KHz (2nd)
SCAN SPECIFICATIONS
Scan speed: 20 channels/second
Channel capacity: 64 (PRI)
64 (SCAN)
Scan detection:
Scan resume delay:
Carrier, tone or vacant channel
0.3, 2.5/5 seconds or infinite
5