Restored A Defective Power Supply And Motherboard In Samsung Monitor 632NW
This monitor belongs to the hospital where I work. It was brought to me with the complaint that it sometimes gets on and sometimes it takes longer time. As the IT administrator helped me clean the set after I opened it there itself, I carried only the panel, power supply board and mother board along with the keyboard strip. When I looked at the power supply, it had such a lot of dry solders on it that I wondered how it was working still! I checked the ESRs of the caps both on the PS board and Mother Board. Most of these were way out of range.
So I replaced all the caps on the PS board and also did a thorough retouch. I have the habit of checking for any man-made short after a retouch of the complete board. I used my microscope for inspection and indeed I found two pins of a transistor were shorted! From my experience I have learnt that after we retouch the board, it is mandatory for checking what we did thoroughly, as any careless mistake done by us can spoil the entire board or even the device. Rectified the mistake and thoroughly cleaned the board, which looked like fresh (Did it breath a fresh life? I felt so when I looked at it!)
Then took the mother board for replacement of caps. As this PCB is multilayered, I used my ever time method of holding the aluminium capacitor by a nose pliers and gently shaking it to both sides, opposite to the soldered legs. By doing it gently and holding the cap close to the board, it will come off by itself. I have explained this method in a few of my previous articles and do not want to repeat it here. (Micro Switch Found Short In Sony Car Stereo | Electronics Repair And Technology News (jestineyong.com)) There was some video also in Youtube, but now I am unable to remember or fetch it.
After cleaning the board thoroughly, I reconnected the PS and mother board to the panel. It was found working very well. Brought these to the Hospital and assembled the Monitor back.
Switched on and found it was working very well there too. Mission accomplished and satisfaction had ample reason to jump into its collection bag.
Special notes: (1) Always make sure that our work is rechecked very well, especially when we do a mass retouch of the board or replacement of components. (2) It is a good idea to make sure that the polarity of the components removed match with what is marked on the board. I have had experiences, where even reputed manufacturers’ made mistakes. They do release service bulletins to their technical service team, but we would never get it or know about it!
(3) Always check the new caps for ESR and value and never take these for granted. Shorted caps, value different caps etc. are often found. (4) Search and do self-learning to sharpen our troubleshooting and rectification techniques. (5) Do your best to give a fresh life to the device you set your hand on, and do what best you can not to allow it to come back soon!
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 Restored A Lovely LED Surface Panel Light