Some Confusion About Transformers In ATX SMPS
When we refer circuit diagram of any SMPS, we found transformer diagram indicates Primary winding & Auxiliary winding on Left side and secondary windings on right side. Like indicated in this diagram
In ATX (COMPUTER) Power Supply we found transformers on actual PCB is like this….
It is always confusing to determine exact transformer internal winding connected to which pin on the PCB.
When we trace the transformer windings on the circuit as per the circuit diagram & while testing continuity of winding we get some doubtful readings. Because actual windings on transformer is differently connected.
Best way to understand the circuit while repairing any power supply always remove the Transformer & check the winding connections across pins. This will give you clear picture of Transformer connections on actual PCB.
So here I am sharing quick reference how ATX SMPS Transformers internal windings connected.
(Transformer Pin solder side view on the PCB)
Hope this will help to understand the circuit while troubleshooting the ATX SMPS.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles on Repaired Mosquito Racket With Battery Charging Problem
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Albert van Bemmelen
April 6, 2024 at 5:15 pm
Thanks for this detailed report about the in ATX power supplies used transformers Yogesh!
We never can have enough insight knowledge of these important technical facts.
Imoudu.O
April 7, 2024 at 4:49 am
Good explanations of this transformer,I'm yet to repair one though. Thanks for sharing sir
Yogesh Panchal
April 7, 2024 at 11:18 pm
your Welcome! Imoudu.O
A D Rana
April 6, 2024 at 5:19 pm
Sir,
I am facing some problem SMPS, in which IRFP460 MOSFET switches the Power supply. Heat sink of it got very hot within some times & Heavy cheaterring sound coming from main power switching transformer.
After some seconds internal Rectifier Diodes at input of the AC Section gets burnt.
Please guide me for testing of transformer of SMPS?
Yogesh Panchal
April 6, 2024 at 6:06 pm
A D Rana,
Check out put of the circuit is not fluctuating or over Voltage.
Replace all bridge diode, Test main filter capacitor.
You can't figure out Transformers for same winding shorted internally,First trace the circuit make a small diagram of transformer, Remove the Transformer from the circuit & Check if it shows any shorting with other winding as per the circuit diagram you made.you can check visually for any burn marks on the winding you can find out burning smell also.Check PWM Section & Surrounding Components by cold & Hot testing.
ARBALASUBRAMANIAN
April 6, 2024 at 9:23 pm
Okay very good information
Kindly let me know permissible winding resistance values for ascertaining its healthiness
Yogesh Panchal
April 7, 2024 at 11:24 pm
Thank You! ARBALASUBRAMANIAN,
There is no fix value for Windings of these type of Transformers it varies as per Manufacturers Circuit Design Requirement.
Parasuraman S
April 6, 2024 at 10:30 pm
Vow! That's a lot of valuable information! Many thanks!
Yogesh Panchal
April 7, 2024 at 11:25 pm
Thank You! Sir
Tayo
April 7, 2024 at 9:53 am
Thank you for this article Yogesh. Im ashamed to admit that i have never truly mastered the art of checking/testing transformer. Very hard for me to tell a short versus normal winding reading. Even my Blue meter gives subjective readings on transformers (i believe the literature says its not useful for testing some types of transformers)
Yogesh Panchal
April 7, 2024 at 11:26 pm
Thank you ! Tayo
Waleed Rishmawi
April 10, 2024 at 10:26 pm
Thanks for sharing this technical information.. it is good to know but unfortunately power supplies that that in my home town are not repaired any more because they are very cheap to buy and replace. Have a blessed day
Yogesh Panchal
April 11, 2024 at 2:54 pm
You are right! Waleed
Peoples are not wasting there time to repair because material is easily available with cheaper cost in all Metro cities,But still these type of repairing work is happens in rural area where logistic or Traveling time & Expense is involved.