Beware Of These Fake PWM ICS
In this article you can learn (1) When to conclude a replacement PWM is fake (1) What to do when a replacement is not available (3) How to check SMPS using a module (4) How to connect a five wire Module
This computer Monitor belonged to the Hospital where I work and was brought to me with the complaint that they heard a loud noise and it went dead. I opened it and cleaned the inside assisted by my colleague and carried the display with boards to my home.
On check-up, I found that the TOP Series PWM IC was burst. I replaced the electrolytic capacitors and the PWM with TOP256EN, as I got this number from another technician friend, since the last number of burst IC could not be read. I also did a thorough retouch of solder points on the board.
But, no output came. I replaced the opto-coupler and TL431 and two electrolytic caps in the primary. Looked for any defective components in the primary and secondary and could not find any. So removed the IC and connected a three wire SMPS module, by connecting its red to B+ return from SMPS transformer primary and black wire to ground.
I left the Green without connecting as it is not required for testing. I got the desired outputs indicating that there was nothing wrong with the primary and secondary section.
This indicated that the primary switching section and secondary sections were ok. There could be something wrong with the feedback circuit, either in the primary or secondary or the new IC was fake. In order to make sure, I connected the following 5 wire Module:
Yellow to the source pin of Mosfet (B+return path from SMPS), Black to Hot ground, Red to Run DC diode, White to Opto pin 4, and Green to B+. I cut the track of Opto pin 3 and grounded it (Emitter of the photo transistor inside). When I switched on, the outputs were present and voltages ok.
So, connected the PS to Mother Board, which was already connected to the Panel and found it to be working. So it was a case of fake IC! (Experts to comment on this, please!)
Brought it back to Hospital and fit it inside the case. Here is a picture of the components replaced:
Mission successfully completed paving way for substantial satisfaction jumping into its bag!
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous article on Dry Solder And Defective Capacitors Found In Philips AZ380/94
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Tayo
February 17, 2022 at 8:18 pm
Parasuraman: the Sherlock Holmes of the repair world! Well done Sir. Very concerning about fake components. Unless you buy them from reputable sources or pull them from other components yourself you can never really know unless you have ruled out all other possibilities by testing, trial and error. But this may take a lot of time and head-scratching. Thanks for detailing the work around for verifying the SMPS was indeed good. I'll research this further.
Parasuraman S
February 18, 2022 at 12:47 am
Many thanks for your detailed comments!
António Carvalho
February 18, 2022 at 3:57 pm
Hello
Can you please give more details about this 5 wire module?
Thanks
António
Parasuraman S
February 18, 2022 at 10:34 pm
Best help will be from the web. I think even Jestine Yong had written a book or article on this. The datasheet of the IC also provides the information. Many thanks!
David
February 17, 2022 at 8:20 pm
It was a nice repair.
Can you please explain more the external connection you did.
I did not understand it.
Thanks
Parasuraman S
February 18, 2022 at 12:53 am
Yellow to the source pin of Mosfet (B+return patch from SMPS), Black to Hot ground, Red to Run DC diode, White to Opto pin 4, and Green to B+. I cut the track of Opto pin 3 and grounded it (Emitter of the photo transistor inside). When I switched on, the outputs were present and voltages ok.
Read the word patch as path. Kindly let me know which one out of the above, you are not able to follow.
Waleed Rishmawi
February 17, 2022 at 8:45 pm
i ordered about 20 pieces of this part number and 7 of them were not working so I threw them in the trash. there is a lot of bad parts out there not just this part only but other part numbers. the problem is the cheap made for less price and that is the main issue here. have a blessed day
Imoudu Onwumah
February 18, 2022 at 12:34 am
Whenever I want to buy ic in my local market I make sure ic given to me carries the same logo of original one, however buying on-line this is impossible.what can we do!!.Thanks for sharing.
Parasuraman Subramanian
February 18, 2022 at 3:33 pm
Yes. True! We are forced to take this risk, sometimes burning our fingers!
Parasuraman S
February 18, 2022 at 12:54 am
Many thanks, dear, for your comments and sharing experience.
ANIL KUMAR V K
February 17, 2022 at 9:18 pm
Excellent work sir, ❤
Parasuraman S
February 18, 2022 at 12:55 am
Many thanks!
Albert van Bemmelen
February 17, 2022 at 11:00 pm
Thank you for again showing how to properly use those special replacement 5 wire DM0565R power modules Parasuraman. I still have try to use them successfully myself because on some small 5V switching power adapters these never seemed to work. Probably due to a failing smd component somewhere in the circuit.
Parasuraman Subramanian
February 18, 2022 at 3:35 pm
I have used this module in adaptors. It worked! Many thanks for your comments and share!
Babu M S
February 17, 2022 at 11:46 pm
Very good repair work sir,more over your given alert for the fake ic. Thak you very much for sharing.
Parasuraman Subramanian
February 18, 2022 at 3:35 pm
Many thanks!
Yogesh Panchal
February 18, 2022 at 2:19 pm
Sir,
In past Technicians store some Common IC Used in TV & Audio system but Now a days storage of this type of IC Is useless, because every different model of the same company uses different parts Specially PWM IC.
anyway these module works well.
Parasuraman S
February 18, 2022 at 10:35 pm
Many thanks for your comments and inputs!
Paul
February 18, 2022 at 2:34 pm
Who is the seller of the bad, fake components?
This is very important to avoid such traps in the future.
A hand drawn schematic of the circuit ( "Dave Cad" ) along with the text will be VERY USEFUL.
I AM STILL WAITING FOR BETTER QUALITY PICTURES. The attached pictures have low resolution.
Parasuraman S
February 18, 2022 at 10:40 pm
Originating from China! I am sorry, the resolution is not as per your liking. These are taken in my mobile camera. Shaking of hands and other problems might affect quality. I cannot afford to buy a costly camera for this purpose. I am not good in drawing sketches. Whenever I have tried, I end up in wasting several sheets of paper. Trying to do it in the computer also cumbersome. But shall give it a try. Many thanks for your comments and very valuable inputs!
Arun Kumar
February 19, 2022 at 1:48 am
Dear sir,
I request you to start an online tution of servesing electronic gadgets methodically,so that we can learn your vast experience/approach to problem solving.
I love the way you present the exercise that is carried in achieving the target.
Yogesh Panchal
February 19, 2022 at 11:06 pm
Sir,
Just use proper light on the object you want to capture; Put your camera on some BOX or on Table & put the object on Ground surface and just arrange to adjust the height by adding some "sweet box size" Box as per coverage object area & just Click the photo as seen on second Photograph of IC number reads Clear that means Your Camera quality is Neat just required little arrangement so that camera should not shake while clicking or use 10Sec.Timer on your mobile phone and just leave the camera for auto clicking after adjusting coverage area.
All the best.
Parasuraman S
February 20, 2022 at 5:23 pm
Many thanks Yogesh bai! When I do my service work, my focus is on the work and many times I even forget to click. Taking such professional photographs in between will cut our flow of thinking and work. Well, to tell you frankly, when I am engrossed in my electronic servicing, I find even the essential interruptions for food, natural call etc a real menace! The flow of thinking and aggression applied to attack the problem and solve over shadows all other such requirements. So, kindly excuse and bear with whatever I am able to eke out from such tight schedule!
Parasuraman S
February 20, 2022 at 5:19 pm
Many thanks for your suggestion. That's something I would love to do. But right now I am very tight to find time. My employment in the hospital, this ever loving electronics hobby and other personal works, which includes taking care of my wife, who is suffering from numbness in the right foot for the last few years, keep me very, very busy. In fact, I had to take a break in posting articles, because of series of treatments given to my wife. I am the only bystander for her. Many thanks again for your comments!
Perhaps Jestine Yong can start an online education on payment basis. Anything given free will not get proper value!