Servicing Mercury SMPS KOB AP4400XA
This SMPS was brought in a dead condition. As usual, opened it and cleaned the inside. The computer SMPS is always a haven for dust and moisturized fine dust and it takes a lot of time and might need a lot of efforts to do a thorough cleaning. Especially, the dirt and fine dust get amalgamated with the SMPS fan, and getting it cleaned is very, very difficult. We may have to use different kinds of brushes, including the bottle cleaner brush small and large.
This was a case of dry solder, yet other common faults in this continuously working unit of a computer. The Electrolytic capacitors were also out of range both in its value as well as ESR. So, replaced all the capacitors and patched up dry solders. Following pictures show you PCB, before dry solder patch up and afterwards, the board after cleaning etc. You can see that the board looks very clean and new! Not only do I clean the wires at its base in the unit, but also look for any wear and tear in it.
The SMPS was working perfectly. I had also opened the cleaned and lubricated the SMPS fan. The grease inside the fan becomes hard and sticky and needs lubrication by WD-40. To open the fan, we need to peel off the sticker from its center and spray a very controlled spray of WD-40. In fact, the used high voltage transformer oil is the best for lubrication. It not only serves as a lubricant, but also cools off. In fact, the best lubricant for carbon potentiometers too! Even the noise due to stubborn dirt and dust particles stuck to the carbon track will get cleaned by using this!
Here is the SMPS checked for its proper function, fit back and tested once again, along with a picture of components replaced.
The satisfaction list bulged further!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 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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