Sunday, May 26, 2019

How to modify an ATX Computer Power Supply to 24V

How to modify an ATX Computer Power Supply to 24V

Portuguese Version: Click Here
Many are the cases to want to make a modification in these PC power supplies, because the sources and power ATX are easy to find and every technician has one or two such power supply in their scrap.
With this modification we can easily build a bench power supply, boost electric motors, amplifier circuits, among many other things.
The ATX power supply we are going to use is one of the brand: GMI Power Supply, model: ATX500, 500W of power.
We will take a step by step to facilitate our understanding

The initial observations will be to analyze if it is working, because we can't change something that doesn't even work, isn't it?
To do this, place a wire, or as in my case, a piece of solder by short-circuiting the PSON connector "Green Wire" and the GND "Black Wire"

As in the picture shown.
After everything checked and if everything is OK !!!!

LET'S START

Step 1 - We have to identify the type of controller IC that we have in our source, in my case the IC is the HS8110.

The IC of your PS may be different, what you need to do is look at its datasheet and identify the correct pins.
Step 2 - With the datasheet of the HS8110 shown in the image, we will identify its pinout, as shown in the picture, as we can see, we have the reference pins of the CI, P1, P2 and P3 as inputs:
Pin 1 = 3.3V
Pin 2 = 5V
Pin 3 = 12V.

We'll use to this modification pins 1, 2, and 3, which are the pins that monitor the under-voltages and over-voltages in this IC, in the datasheet is very basic, without much information, being a Chinese PS, it's difficult to find the datasheet of the same with more details, but let's do it anyway.
Step 3 - Identify the output that comes from the 3.3V voltage coil, "in our case" has a load resistor connected in parallel at the output, it will burn if you don't remove that pin from the coil, also it will not be necessary, we'll not use the same.

Replace the output capacitors, they are 16V, if you make the change and do not replace them, they will burst, replace with a 36V to support the voltage after the change.

Step 4 - Let's follow the tracks and identify them in the IC, then we can release the resistors that connect the 3.3v, 5v, and 12v voltage outputs to the IC, and we will simply lift them, thus taking the IC references .

ATTENTION

It is of the utmost importance that you have an anti-short circuit test, in our case, we have the good old SERIES TEST of the incandescent bulb.

CAUTION!!!

DO NOT touch the primary heatsink of the power supply, you may suffer electric shock. "GIVE SHOCK".

Step 5 - Connect the PS with caution in the SERIAL TEST, and test the output voltage, as we can see in the picture, our gave 24.25V without load.

Step 6 - Let's put a small load on a 24V and 1.5A motor, to see the variation.

Remembering that we take all the references of the IC, then it is with its highest oscillation, that is, generating at full steam at its maximum, then it is normal for this voltage to fall when it receives a load.

As we can see, we had a voltage drop from 24.25V to 22.01V

This confirms its operation for several projects.

We have a video on our YouTube channel, we applied several resistors in parallel and reached 200A, for a fraction of less than 1 second, it is obvious, because as the video suggests, it is 200A peak, if it were for normal operation it wouldn't to 50A.

Obviously also that this source already burned, I went to do heavier tests, and she could not stand it.

Conclusion

Satisfied with the project, for its simplicity and that can be used for several other projects, it met the expectations satisfactorily.

Thank very much, any questions, write in the comments.

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For that you want to see the details of the assembly, I leave below the video for you to understand and follow the step by step, this video is with caption just to activate.






Thank you

God Bless You

Shalom




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