Combining PSU rails together

[Pranvi]

Hello friends, I am having an old PSU (power supply unit) that I want to use for testing. But I am having a doubt. If I cut all the wires and together combine all the rails, will the PSU function. I have got a single 5 volt and a single 12 volt rails. I dont think about others. I would like to cap them off and make sure that the power button portion is solderd together. Is it possible to do so. By doing so, Would I be able to get large amount of power in a single rail. Has any one tried it before. If anyone having an idea regarding this, then please let me know.

[Yitzchak909]

Connecting the two rails together is a good idea. You have got a single 5volt rail and a single 12 volt rail. If you really need to power a 12 volt device then you have to connect multiple 12volt leads collectively from different rails. But be cautious while connecting cables and check for correct polarity. You can use this PSU(power supply unit) to test fans and other electrical devices. Multi rail PSU (power supply unit) are more costlier than the single rail PSU(power supply unit).
This is because, the single rail PSU doesn’t need any OCP circuitry.

[pddaugusto]

Its true that the single rail PSU(power supply unit) are less expensive if compared with the multi rail PSU. Connecting multiple +12 rails volt together is very safe. Due to bit of voltage difference between the wires, it may be possible for some current to flow backwards. But there is nothing to worry about. It doesn’t make any difference. You can use one wire per rail. when you pull the board you will fond that the wires are soldered together. Multi rails PSU(power supply unit) actually uses OCP circuitry, and this makes them expensive.

[Howitzer]

I have built a multi rails PSU(power supply unit) with my two old single rail PSU. I just used one wire per rail. I took help of romex wires, that came out of the grill as terminals. I labeled them so that they can be identified easily. It is having +3.3v +5v +12v 0v -5v and -12v voltage combinations for different purpose. I brought few crocodile clips and made few Molex female connectors. I made them built in such that no wires were coming out at all. I can use it for testing fans and other electrical devices ranging from 5 volts to 12 volts. I even use the power to magnetize screw driver.

[samar69]

It is common that single rail PSU (Power supply unit) are cheap. The PSU that I used was defective and it had tendency of browning out. So I would rather prefer to get the cheaper one. Single rail PSU(power supply unit) are cheap but have many disadvantages. They can power the components even with irregular power supply, they are very sensitive to temperatures. If they get overheated then may give bad performance or lose the power. They do not meet the ATX standardizations. Only a soldered fuse cannot provide a real circuit protection.