Power Supply Troubleshooting & Repair

by Lanny Logan

• ISBN13: 9780790611389
• ISBN10: 0790611384
• Edition: 1st
• Format: Paperback
• Copyright: 1998-08-01
• Publisher: Prompt (DPI - 8/01)

Summary

This practical guide to switch-mode power supplies is designed to provide technicians with a better understanding of how power supplies operate. It also provides practical, useful procedures to follow when you are troubleshooting switch-mode power supplies.

Table of Contents

Introduction	1	(7)
Switched-Mode Power Supplies: An Overview	7	(30)
Types of Configuration	9	(1)
Type of Controlling Device	9	(1)
Type of Oscillator	9	(1)
Type of Power Control	10	(1)
Source of Secondary Feedback Voltage	10	(1)
Seven Parts of a Switched-Mode Power Supply	10	(21)
The Bridge Circuit	11	(1)
The Oscillator Circuit	11	(4)
Secondary Voltage Sources	15	(1)
Sensing Circuit	16	(1)
Error Signal Feedback Circuit	17	(2)
Regulating Circuit	19	(1)
Protection and Other Special Circuits	20	(11)
Troubleshooting Tools	31	(1)
Troubleshooting the Switched-Mode Power Supply	32	(5)
Pulse Width-Controlled Discrete Switch Transistor Switched-Mode Power Supply	37	(22)
Protection Circuits	40	(1)
Troubleshooting Using the Block Diagram	41	(8)
More, Special Protection Circuits	49	(3)
75-Volt Overvoltage Protection	51	(1)
Low-Frequency Protection Circuit	52	(1)
More Troubleshooting Tips	52	(7)
Free-Running Pulse-Width Controlled Switched-Mode Power Supply	59	(28)
Types of Protection Circuits	62	(1)
The Troubleshooting Sections	63	(10)
C604 Not Positive	65	(1)
Troubleshooting Full-Power Supply Failures	66	(7)
When the TV is Turned On	73	(1)
Checking the Protection Circuits	73	(4)
Overcurrent and Overvoltage Protection Circuit	77	(1)
Troubleshooting the Circuit	77	(10)
No Voltage Potential on C604	78	(1)
Negative Voltage Potential on C604	78	(1)
Standby (Only VCR On)	79	(1)
Checking the Feedback Circuitry	79	(1)
Checking the Regulating Circuitry	80	(1)
The Potential on C604 is Positive	80	(2)
Failure Occurs in the Full-Power Mode (When the TV is Turned On)	82	(5)
IC-Controlled, Fixed Frequency, Dual Switched-Mode Power Supply	87	(30)
Standby Switched-Mode Power Supply Operation	89	(2)
Standby Protection Circuit	91	(1)
Full-Power Section Operation	91	(2)
Full-Power Section Protection Circuits	92	(1)
Standby Section of Controller IC401	93	(5)
Full-Power Section of The IC Controller	98	(1)
On/Off/Shutdown Controller IC Operation	99	(3)
Standby Switched-Mode Power Supply Operation	102	(4)
Troubleshooting the Standby Switched-Mode Power Supply Section	106	(1)
Operation of the Full-Voltage Switched-Mode Power Supply Section	107	(10)
Turning On the full-Power Section	109	(2)
Checking the Full-Power Section Protection Circuits	111	(1)
A Note on Troubleshooting the Full-Power Section	112	(5)
IC-Controlled, Foixed-Frequency, Dual Switched-Mode Power Supply with Discrete Shutdown Circuit	117	(28)
Operation of the Standby Section	118	(4)
Operation of the Full-Power Supply Section	122	(2)
Troubleshooting the Standby and Full-Power Sections of the IC Controller	124	(12)
Standby Section of the IC Controller	128	(3)
Full-Power Section of the IC Controller	131	(5)
Troubleshooting the Standby Switched-Mode Power Supply	136	(2)
Full-Power Switched-Mode Power Supply Section	138	(7)
Protection Circuits	140	(2)
Troubleshooting the Full-Power Section of IC401	142	(1)
Checking Pin 2 of Optocoupler IC402	142	(3)
IC-Controlled Switched-Mode Power Supply With Built-In Switch	145	(18)
The Protection Circuit	148	(1)
Troubleshooting	148	(2)
The Circuit Schematic	150	(13)
A Look at Linear Regulated Power Supplies	163	(17)
IC410	167	(7)
Protection Circuits	174	(1)
Troubleshooting This Circuit	175	(1)
Troubleshooting Problems	175	(5)
Index	180