# Power Supply Unit (PSU) Modding Guide



## rakesh_sharma23 (Dec 16, 2014)

Power Supply Unit(PSU) Modding Guide


*i.imgur.com/vczDwtY.jpg


Power Supply Unit (PSU) or more often called SMPS (switching-mode power supply) is the most important component of a Computer system. Reducing high voltage from your wall plug to lower operating voltages for all the pc components inside your PC.


For every PC purchase, a good PSU should be on top priority. But most of the times it is the least considered part. Most of the time PSU is considered as a “free-be” that comes with the PC cabinet.


50% or more running PCs or a new purchased PC is having a cheap PSU in it. And whenever I suggest anyone to change to a decent PSU, always I get the same reply “for last 2 or more years I am using the PC with this cheap SMPS and I didn’t faces any issue at all, so why to upgrade ?” And I am sure many of you also have same answer for me.


So now through this article I am not convincing you to purchase a new PSU. I will just try to clear why your cheat PSU is not good for your PC components and your data. Even after if you still want to stick with your cheat PSU, than following is a guide which can help you mod your cheap PSU to make it little stable and can give a new life to your PC.


*What is a cheap PSU and Why it’s not good for my PC ?*


All cheap PSU are




Over rated. All cheap PSU have a label saying 450W or 500W watts, but really they are within a range of 150-200 Watts. A 150-200 Watts of power is ok for an office or home PC with entry level hardware.
Have high voltage ripples and noise in their output voltages. These high voltage ripples slowly kill motherboard's VRM section and power filters. High voltage ripple is also the main reason of Hard-disk failure.
Poor efficiency. This type of PSU uses old switching-mode technology which results in about 50-60% efficiency.
Low quality components. As the word “Cheap” says by itself that these PSU use all type of low quality components as possible. From noisy fan to thin wire cables and connectors, poor quality electronic components on PCB.
More heat. Lower efficiency means more heat and with a poor fan this heat remains inside the PSU case slowly cooking other components too.
No protection circuitry. These PSU have just a main fuse in the name of protection. Over load, under load, Main Surge, thermal, etc .. you name any protection technology and I am sure you will not find any inside these PSU.
Fake CE, FCC, RU and other certification labels.



So a cheap PSU is like a time-boom inside your PC ready to die without reason, along with killing one or more PC components too.


My suggestion is don’t buy these cheap PSU or if you have one try to get a decent PSU.




*Modding a cheap PSU.*


If you still love your cheap PSU, than this mod will help you in making the PSU and PC more stable and reliable.


*WARNINGS*


Before proceeding


This mod involves Main AC Electricity and you should have experience in handling electronic, tools and high voltage components.
You should not open the PSU case with main power plug in.
Even after unplugging Primary Capacitors store a large amount of power enough to start a fire, give a shock or burn skin.
You should know how to solder and handle high voltage components.



I AM NOT RESPONSABLE FOR ANYTHING YOU DO WITH THE INFORMATION HERE


I am not responsible if you electrocute yourself or anyone else, if you blow something up, or if you burn your house down so be careful.




*First look.*


This PSU cost me only Rs.500. The only reason I chose this PSU is that at least it looks like they have labeled it’s power handling correctly. It can handle 200Watts max.


The overall PSU design is not all that bad. Since there is no PFC and EMI circuit, resulting in only a 150W load handling capability.
*i.imgur.com/TkTOcQn.jpg




Inside of the case.


First impression, many components on the PCB are missing. Mainly the surge protection section is not there.
*i.imgur.com/0SVtVbz.jpg
*i.imgur.com/nzVWLPq.jpg


In the name of protection we are having a main fuse and inrush current limiter (an NTC)
*i.imgur.com/xNfWvC1.jpg


Poor primary capacitors
*i.imgur.com/AjM43aa.jpg
*i.imgur.com/VWq8xxY.jpg


No Fan connector, but at least a thermal sensor for fan speed regulation.
*i.imgur.com/AWwxJcs.jpg


Low capacity and poor quality secondary capacitors
*i.imgur.com/iLBgBSH.jpg


Missing 3.3 voltage filter coil.
*i.imgur.com/9Ls5OHM.jpg


Now I will be adding all the surge protection components, replacing primary and secondary capacitors to reduce voltage ripple. Since secondary is having all labeled 1000uf capacitors (I am sure they are even lower in capacitance), I will be replacing them to at least 2200uf or more according to the space available on the PCB.


*Removing PCB*


Unscrewing and removing the pcb for modding.
*i.imgur.com/uMhMFZ0.jpg


A closer look on primary and secondary capacitors
*i.imgur.com/QmQ20Ns.jpg
*i.imgur.com/KhYM2UQ.jpg


Replacing primary capacitors (CapXop 470uf / 220v) with Nichicon 560uf/250V


Power capacitors must be discharged before de-soldering. I do it by connecting 1K ohms 10W resistance directly to terminals of the capacitors for few minutes.
*i.imgur.com/MPgHZrx.jpg
*i.imgur.com/rzHY6oU.jpg


Now for surge protection circuit. The recommended components for this stage are two ferrite coils, two ceramic capacitors , one metalized polyester capacitor and one MOV (metal oxide varistor) on each main rail.


Adding Hitano CTX 0.47uf capacitors
*i.imgur.com/v4KIMW4.jpg


Now adding two ferrite coils and two MOVs
*i.imgur.com/HM6cNdL.jpg
*i.imgur.com/VpEL7cs.jpg
*i.imgur.com/QOpjSvz.jpg


Replacing secondary capacitors. First standby 5 voltage cap.


1000uf/6.3v replaced with Rubycon 1000uf/10v
*i.imgur.com/Snjbmdy.jpg


Also added a filter coil for 3.3 v supply.
*i.imgur.com/YZzakfV.jpg


Finally all done.
*i.imgur.com/uS6qbCf.jpg


Since this PSU is new so I think there is no need to replace the fan. But if you are modding an old PSU, you should replace the fan also.


*Result*


Now PSU is stable, voltage ripple also reduced and now EMI filter and surge protection is enable.


Now just a Image of a Good PSU from Inside. This is Corsair CX430 PSU
*i.imgur.com/LuENZsp.jpg




Hope this will give you a good idea about modding a PSU.


Thanks


Rakesh Sharma


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## adityak469 (Dec 16, 2014)

man you put real efforts into your posts!


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## rakesh_sharma23 (Dec 17, 2014)

Thanks bro.


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## Nerevarine (Dec 17, 2014)

Mother of god, you are a genius


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## cute.bandar (Dec 17, 2014)

Unless you really know what you are doing.. *DON'T OPEN THE PSU*

Teenager in Shawnee, Oklahoma dies after being electrocuted fixing his computer | Daily Mail Online



> Many people don’t realize that the power supply  - which is made up of capacitors - carry a charge for several days or weeks, even when they are unplugged and broken.
> 
> Read more: Teenager in Shawnee, Oklahoma dies after being electrocuted fixing his computer | Daily Mail Online
> Follow us: @MailOnline on Twitter | DailyMail on Facebook


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## rakesh_sharma23 (Dec 17, 2014)

Yes. Take great care while working with Power electronics. 



cute.bandar said:


> Unless you really know what you are doing.. *DON'T OPEN THE PSU*
> 
> Teenager in Shawnee, Oklahoma dies after being electrocuted fixing his computer | Daily Mail Online


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