Introduction
By Shahrizal Shariff

A few months ago I've posted a guide on how I successfully mod my icute psu. After that I receive a lot of questions and the most common one is "My psu is xxxx (icute, aopen, cap ayam ...) how to mod? ". At that time I was busy with my industrial training, so many questions are not answered....sorry....

I've finished my study last month so have plenty of time to waste. Have 4 different psu here at home so I decided to write a more complete guide to mod psu without the vsense line.

Here are the psu that I have:

~Digituz model: ATX-400W/P4
~L&C Technology model: LC-250ATX
~Cap Ayam model: 300W psu
~iCute model: ATX-450W/P4

This guide is divide into:

1. 5v & 12v line mod
2. 3.3v line mod
3. applying the mod on iCute psu
4. Tips & Trick


Some Warnings and stuff you should now.

1. Its dangerous to play with electricity..you could shock or even kill yourself ...so be careful ( discharge your psu before opening it up)

2. This mod only increase the voltage output of your psu. It will not increase its wattage nor will it convert your psu into true power .

3. Yes...your psu might be damage by doing this mod and it may also blow up ...so stop posting messages like "I think you gonna blow your psu". I get a lot of this messages in my last post and it is very annoying

4. You will void your psu warranty so keep this in mind.


Enough with this now lets move on with the show...



1. 5v & 12v line mod.

Here are the list of psu and the IC that they use to control the 5v and 12v line. Please also note that both of the line will increase simultaneously together. There is no way of modding only a single line either 5v or 12v.

~Digituz model: ATX-400W/P4=======>IC: TL 494 CN
~L&C Technology model: LC-250ATX===>IC: DBL 494
~Cap Ayam model: 300W psu========>IC: KA 7500 B
~iCute model: ATX-450W/P4=========>IC: TL 494 CN

As can be seen from above, most of this psu are using the same IC which is the 494 16-pin. The alphabet in front or the serial number can be ignored because it differs between different manufactures. The only exception here is the cap ayam model which uses the KA 7500 IC. But this IC can be moded the same way as the 494 does.

List of item needed for the mod:

~50k pot
~ some wire
~soldering stuff

Here's what you got to do:
You have to solder the pot to pin 1 of the IC and the other end of the pot to ground. Look at the diagram below:



Remember to set the pot to full resistance before powering on. Decrease the value of the pot to make the voltage go higher.


2. 3.3v line mod.

The 3.3v was very difficult for me to find. The IC actually looks like a transistor (yes...a 3-pin IC). Luckily I notice the markings on the iCute pcb. Other transistors are mark with Qn (n=1,2,3...) but one transistor is marked with ICn...that's the IC that we're going to mod. Here are the list of psu and their IC.

~Digituz model: ATX-400W/P4==========>IC: TL 431
~L&C Technology model: LC-250ATX======>IC: SD 431
~Cap Ayam model: 300W psu==========>IC: TL 431
~iCute model: ATX-450W/P4===========>IC: TL 431 / CP 431

Again the alphabet in front or the serial number can be ignored because it differs between different manufactures. This mod is a little bit tricky because you have to find resistors connected to the Reference pin of this IC. Look at the diagram below.

List of item needed for the mod:

~10k pot
~ some wire
~soldering stuff



For this mod you have to find the resistor R1. This resistor will be labeled differently on your psu pcb, so keep that in mind so that you will not mod the wrong resistor. To find this resistor, first you must find the IC. Determine the Ref pin and from there determine the resistor that is directly connected to this pin. There will be two resistors connected to this pin, one is connected to ground and the other is connected to a +v source. The one connected to the +v source is R1.

You will have to desolder one of the R1 resistor leg and connect it in series with a 10k pot like in the diagram. That's it, you're done.

Remember to set the pot at the lowest resistance before powering up the psu. Increase the pot resistance for higher voltage.


3. Applying the mod on iCute psu.

Here are some pictures and brief explanation of my modded iCute psu.

5v & 12v line mod



50k pot connected between pin 1 and pin 7 of the TL494CN


3.3v line mod



R1 is labeled as R77 on iCute pcb. Connect in series with 10k pot


Results









4. Tips & Trick

1. Measure the voltages using a multimeter. Don't trust the readings of your bios or any third party apps.

2. You may use a trimmer instead of the large pot that I'm using. A trimmer is much smaller so can fit easily inside your psu.

3. Remember that for the 5v&12v mod lower resistance = higher volt but for the 3.3v mod higher resistance = higher volt.


4. Remember to set the pot to the highest resistance for 5v&12v and lowest resistance for 3.3v before turning on the psu.

5. Adjusting the pot on-the-fly while the pc is running is highly not recommended. You may burn other components of your pc if you accidently turn the pot too much. Adjust the pot outside your rig and measure using multimeter. To turn on the psu outside your rig, short the green wire with any black wire at the 20pin atx connector.

6. If you want to overclock your rig to the max, do yourself a favor and go buy those true power psu like antec and enermax. You wont regret it .(although i'm still stuck with my icute though )


That's it for now...happy modding
p/s: If you need help pm me.

This post has been edited by Shah81: Jan 26 2006, 02:04 AM