Troubleshooting & Repairing Consumer Electronics Without a Schematic

481 Pages·2004·14.483 MB·English

by  Davidson, Homer L

Troubleshooting
and Repairing
Consumer
Electronics
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Troubleshooting
and Repairing
Consumer
Electronics
Third Edition
Homer L. Davidson
McGraw-Hill
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Contents
Introduction xv
Acknowledgments xvii
1 Servicing methods without a schematic 1
Locating critical components 2
Just listen, man 3
Hands on 3
Too, too bright 4
Audio pops and cracks 5
Smoke and fire 7
Under those eyes 8
Keep at it 9
Same chassis, different model 9
The same train tracks 10
Lines down the road 11
Identify part numbers 11
Resistor color codes 13
Flat capacitor color codes 14
Foreign capacitors 14
Dogs of all kinds 14
Cool nights and hot days 16
Double trouble 18
Lightning damage 19
Down below 19
Outside the chassis 20
Do it today, not tomorrow 20
Intermittent problems 21
Time is precious 22
Test points 23
v
vi Contents
Say it isn’t so 23
Ten points of servicing 25
Safety measures 28
2 How to locate, test, and repair 31
With only a DMM 31
Correct electronic test equipment 32
Who’s on first? 35
Case histories 36
Isolation 38
Location, location 38
Out of bounds 41
Lightning damage in a TV chassis 43
Burned and damaged 43
Ac input hot grounds 44
TV SMPS hot grounds 44
Running warm 45
Red hot—do not touch 45
Same circuits, another chassis 46
Resistance in-circuit test measurements 47
Continuity tests 48
Leaky or shorted transistor resistance tests 49
IC resistance tests 50
Sams Photofacts 51
Electronic Servicing and Technologyschematics 52
The various waveforms 52
Signal injection 53
Troubleshooting with an external amp 55
Transistor in-circuit tests 55
Digital transistor tests 57
NPN or PNP 57
DMM diode tests 58
Safety transistor replacement 59
Signal in and out tests of IC components 59
Voltage injection 60
Removing and replacing a defective IC 61
Here today and gone tomorrow 62
Component replacement 64
Low and behold 65
SMD components 65
Flat or round 66
Removing SMD parts 67
SMD replacement 68
ESD FCC ID numbers 68
Cleanup 69
Contents vii
3 Troubleshooting and repairing audio amps,
large and small 71
List of audio test equipment 71
Required test equipment 72
Listen, listen 75
The dead chassis 75
Only a whisper 75
Repairing the audio amp 76
Stereo IC amp repairs 78
Repairing the cassette amp 79
Auto radio amp problems 85
Large stereo amp repairs 88
Troubleshooting CD player audio circuits 90
Servicing the TV audio amp 93
Extremely high-powered amps 96
4 Servicing auto receivers 103
Required test instruments 103
The power supply 104
The front-end radio section 104
The rear section 106
Variable-capacitor tuning 107
Inductance tuning 107
Varactor tuning 108
Keeps blowing the fuse 108
Common auto radio failures 109
New FM circuits 113
SMD components 114
Silent listening 115
Early car radio audio output circuits 116
Auto radio hookup 120
High-powered amps 120
Dismantling high-powered amps 122
Locating the correct components 123
Transistor high-powered amps 124
IC high-powered amps 124
Troubleshooting high-powered power supplies 126
Servicing high-powered amps 127
Bridged amp outputs 128
Two-channel amp hookup 128
Matching impedance 129
High-powered speaker hookup 130
Auto radio speakers 130
Speaker problems 133
viii Contents
5 Servicing cassette players 135
Required test equipment 135
Pocket cassette player layout 136
The portable cassette player 136
Auto radio/cassette player 136
Check out that cassette 138
Slow speeds 138
Will not eject 139
Dead, no sound 140
Poor tape motion 140
No fast-forward or rewind 141
Tape everywhere 142
Jammed tape 142
Squealing noises 143
Too much oil 143
Poor erase 144
Poorly soldered connections 145
Dead left channel 145
Intermittent operation 146
Under that magnifying glass 146
Locating and replacing bad transistors 146
Locating and replacing a bad IC 148
Recording problems 149
The boom-box cassette player 154
The auto cassette player 158
6 Troubleshooting CD players 167
Laser diode circuits 168
Digital-to-analog (D/A) converter 173
CD power supplies 173
Check those electrolytics with an ESR meter 175
Focus amp problems 176
Battery focus coil check 178
Tracking amp problems 178
Loading motor problems 178
Disc and SLED motors 180
Intermittent skipping 181
No play, dead operation 182
Noisy sounds 183
The portable CD player 183
Boom-box CD circuits 185
Similar diagrams 186
The defective CD motor 187
Motor drive circuits 189
SMD components 189
Troubleshooting D/A circuits 190
Contents ix
Defective mute system 190
The CD changer 191
Servicing headphone circuits 194
Troubleshooting servo circuits 195
Loading problems 196
Actual CD case histories 196
Critical waveforms 197
7 Troubleshooting the TV chassis 201
TV chassis components 201
The most troubled sections 202
Locating TV components 203
Relay problems 203
Horizontal circuits 204
Horizontal circuit problems 205
What keeps destroying the horizontal output? 207
Old faithful replacement 209
Horizontal output problems 209
Horizontal voltage injection 209
Safety first 210
Pulled in on the sides 211
Flyback problems 211
Red-hot output transistor 213
Yoke problems 214
Intermittent shutdown 216
High-voltage shutdown 217
TV chassis shutdown 218
High-voltage problems 219
The bow and arrow 219
Critical horizontal waveforms 220
Vertical problems 220
System control 230
Tuner on the side 232
No raster or a bright raster 234
Color symptoms 235
Green with envy 236
Surface-mounted components 237
The “tough dog” 237
On-screen display 237
EEPROM problems 238
Audio problems 239
8 Servicing power supplies 241
Half full 241
The damaged bridge 242
Transistor regulators 243