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Overcoming resistances in ATX PSU'S

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Oct 8, 2001
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CANADA!!
I was just converting what i learned in tech class to computers and got not half bad of an idea! The base of my idea is that in a cars ignition circuit there are resistances and if the resistances are significant then the car will not turn over. Then my tech teacher told me that in the trade they would have to give computer connectors acid baths to ensure good connection. He said that even when the connector looked spotless, some times they would still have problems with that vehicles computer if they did not clean the connector. So i was thinking that if the smallest smudge of grime can cause majior errors in a cars computer, what is stopping the resistances in our ATX connector and lines from being a problem? Here is a list of problems I have found with many of todays PSU'S

1. ATX does not make good contact
2. ATX wires are made of aluminum instead of copper!(not 100% sure on this just know that alot are silvery instead of coppery in colour)
3. ATX wires are not thick enough
4. ATX wires lack Large connection with psu
5. ATX wires are crushed into ATX pins in the ATX connector instead of soldered.
6. Too much heat resistance.

I plan to remove all the resistances from my power supply and get back to you on my results.
 
You will find that the "Lions share" of the voltage drop occurs across the ATX connection. Sure the other resistances are there, but they do not contribute a significant voltage drop. The more you plug and unplug an ATX connector, the worse the resistance across it becomes. There are conduction enhancing lubricants like DeOxid that you can put on the ATX connector pins to reduce wear from repeated pluggin/unplugging and they also serve as an anti-oxidant. I treat all my ATX connectors with DeOxid. Manufacturers can purchase their hookup wire either in raw copper or tinned copper. Tinned copper has that silvery look to it. I have never seen a PSU that employed aluminum wire. Yes, the wires are crimped into the ATX connector pins on all PSUs, but the quality of the crimps vary a lot. Not necessarily employing too little crimping pressure, but more often not getting all the strands of the wire inside the crimp, or worse, crimping upon the insulation as well as the wire.

Hoot
 
as an extra - I've been looking into the ATX connector because
I have a Tyan 2460 (the connector is rated to 6 Amp - and all the 5Volt lines are constantly carrying at least 5 Amp)

There are several factors that assist the current carrying capacity of a connector.
1/ the surface area actually in contact (a fixed value in ATX standard)
2/ the clamp or spring force holding the two surfaces together.
( some ATX power supplies seem much better than others)
3/ the contact metal - copper or gold being better
4/ the vibration the connector is submitted to.

The last point is probably what promotes oxidation/corosion/micro-welding in the connector - raising the
temperature and causing higher resistance - causing a failure cycle.
Mr Hoot is right on base about using substances to preclude oxidation.
Another method - (standard for hackers) is to double up
the connectors (two connectors- half the resistance)

Keep us posted on your findings - but a system that is running well withing standards might not show much measurable improvements.


Just remember to Shop Smart "Shop S-Mart"
 
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