Several Bad Capacitors Found In SMPS
This work was once again in the Hospital, where the computer SMPS fails quite often. This was dead when brought. First thing, as usual, is always a thorough cleaning inside, outside, SMPS fan etc., including the power cord to the DC wires and connectors. After this was done, inspected the board for dry solder and burst capacitors.
Also the ESR of all of them, and the capacitance after removing. Here are the findings:
As you can notice, the 330uF was 223 and 226uF!
The 1500uF was just .709!
The 1000uF was showing 1.221uF! And now, look at the ESR of another cap!
So, replaced all the electrolytic capacitors and did a thorough patch-up of dry solder from one end of the board to the other, without leaving any point. Checked and ensured that there were no ‘created’ shorts in the process.
Cleaned the PCB using Cleaning Spirit (which is available in the Hospital aplenty!). Look how clean the PCB looks now, like new one! This is what thrills me always! The SMPS fan was also overhauled.
Applied power, after shorting the green wire to ground, and just see how the fan runs smoothly. You can also see the PCB after the dry solder patch work and cleaning!
Here are the voltage readings: (The voltages would become normal when proper load comes from the CPU)
Another work completed to my utmost satisfaction, and needless to say that the list extended further to its way to infinity! Oh! Forgot, here are the bad ‘guys’ ‘extradited’ to the ‘recycle island!’
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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https://jestineyong.com/substitute-electronic-on-off-switch-provided-in-sony-radio/
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Albert van Bemmelen
January 5, 2019 at 5:35 pm
Another very professional repair after replacing 15 bad e-caps! I hope that having to replace all these e-caps makes it still worth your while fixing this 450W Power supply economically speaking. Although it probably was never so clean before and likely will work for another decade without failing. I noticed it was made in July 2010.
Parasuraman S
January 5, 2019 at 8:43 pm
It's economical as the cost of these capacitors will only be very fractional to a new one. Secondly the Hospital is saving on service charges.
Randy
January 6, 2019 at 12:27 am
The same thing over and over, these cheap Chinese 'lytics are garbage and are responsible for failure after failure in electronic circuits. I NEVER use Chinese caps, only those made in Japan by reputable companies like Nichicon, Chemicon, Panasonic, and others. Just think, if the manufacturers used good 'lytic caps, we would be out of work, and things would last for 20+ years, just like in the olden days!
Robert Calk Jr.
January 6, 2019 at 4:45 pm
Good job, Parasuraman.
Roop Gobind
January 6, 2019 at 11:20 pm
Always a pleasure to read your posts. You are so professional in all that you do.
Keep up the good work. God bless
Henrique J. G. Ulbrich
January 7, 2019 at 12:06 am
Very good work, and apparently quickly done. Greetings and thanks for sharing. China is wishing to dominate the world commerce but makes immature mistakes concerning minimum levels of quality of certain products. El caps are a significant example.
Bufford Moore
January 7, 2019 at 12:14 am
I'm impressed that power supplies that have to (in theory) meet very high regulatory requirements for hospital use are so often built with very low quality components. In particular, I noted the ChongX capacitor that I have found to be so unreliable that when I work on devices, I replace any I find without respect to how they test. Some might consider this wasteful, but I had a number of repairs come back after one of these failed even though they appeared and tested OK at the time of the original, unrelated repair. Since I have started doing this, none of the repairs have come back to me.
Parasuraman S
January 7, 2019 at 1:05 pm
Very valuable input on ChongX Caps.Thanks!
Justice
January 7, 2019 at 8:09 pm
My concern is what caused so many caps (14) to become faulty. is it perhaps the surge current(s) ? Thank you for the wonderful job.
John Shadbolt
January 11, 2019 at 6:48 am
Great job, glad you fixed it! Please note for future reference that 1mF=1000uF, so some caps may have been OK (at least in the short term).
Best wishes!
Parasuraman S
January 16, 2019 at 5:08 pm
Thanks! I am aware of it. ESR also is being considered.
J. P. Purohit
January 19, 2021 at 5:15 pm
Nice to visit your site Mr. Parsuraman ji,
You article is ver useful to all who repairs such smps and other electronic gadgets, Thanks.