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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