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I've got a Power Supply backplane and 3 comaptible 430 watt powesupplies

P

PaperclipGod

Banned
Weird question, I know, but I hate the thought of throwing out working hardware!

I salvaged some parts from an old IBM 8650 server, produced around 1997. It came with three redundant 430 watt powersupplies, manufactured by Delta. The PS's just slide on rails into a backplane, and the backplane then uses standard AT cables to connect to the motherboard, etc. Two of these powersupplies were never even used, the plugs in the back are still taped up.

If I had all three plugged in and powered on to the backplane, would this be an acceptable power source for a new system? Or would power supplies this old (around 13 years, now) have issues I should be wary of?

Edit: scroll down for pics, like 7th post down.
 
First and foremost, I'd be worried about the quality of the power coming out of the power supplies. Newer hardware is likely to be more sensitive to voltage and output changes. Also, what are you going to plug into a 4-pin P4 system power connector? 24-pin connector for a new motherboard? 8-pin for some heavier boards?

Secondly, get over your minor case of OCD. 🙂 Give them to a computer part recycling center and move on with life!
 
Well, it probably is a bit of OCD... but hey, if these will work, why not use them? Where else am I gonna get a triple-redundant 420 watt powersupply for the low price of FREE? 😀


And yes, RebateMonger, they do have 3.3v rails. The sticker on the back of them reads:

Delta Electronics, Inc.
Model: DPS-420CB A Rev: 0
Input: 100-240V~ /7A,
47-63Hz

+3.3V / 15A / LEVEL3
+5.1V / 32A / LEVEL3
+12V / 16A / LEVEL5

VBIAS(16-20Vdc) / LEVEL3

-5V / 0.25A / LEVEL3
-12V / 1A / LEVEL3
+5STBY / 100mA / LEVEL3

-----
The one thing I'm not sure of is how the backplane handles the PS's - does it only draw 420W from one and uses the other 2 as hot spares? Or dooes it draw 840W from two and use the last one as a hot spare? Or some other config? I know the server works with just one plugged in.
 
They could be connected in parallel, the system will only draw what is needed, But connected this way one PS could take out the others.

Look at the circuit where they are connected in the server case and see if they have any control / monitoring / switching circuit. It probably has something.

It would be easy to install a 4 pin or an 8 pin plug.

pcgeek11
 
Originally posted by: PaperclipGod
Interchangeable how? Physically, or the actual power output is different?
Click to expand...

AT has a power switch, where ATX has a "turn on" circuit you short. I know that much at least.

I suppose a relay could serve the same purpose, though.
 
Originally posted by: pcgeek11
They could be connected in parallel, the system will only draw what is needed, But connected this way one PS could take out the others.

Look at the circuit where they are connected in the server case and see if they have any control / monitoring / switching circuit. It probably has something.

It would be easy to install a 4 pin or an 8 pin plug.

pcgeek11
Click to expand...

Pics!

ps-backplane.jpg
ps-backplane2.jpg
 
There are a few potential issues, several of which have already been mentioned.

Some of the physical cabling will be different; hope you're decent with a soldering iron. You do have all of the voltages required by ATX (and more).

AT has a switch that directly turns the power supply on. ATX has a "soft switch"; the motherboard grounds pin 14 for 20-pin supplies or pin 16 for 24-pin supplies (the green one) on the main ATX connector to instruct the power supply to turn on. I do not know how an ATX motherboard would react to just having the power supply turn on. As mentioned above you could probably use a relay to deal with the difference. Since I am not familiar with the nitty-gritty in how ATX motherboards actually implement PS_ON, my suggestion would be to connect it to an inverter, and use that inverter's output to drive a relay.

The power supply then pulls PWR_OK (pin 8, grey) high when its voltages have stabilized. AT has Power Good (pin 1 on the P8 connector, orange), which appears to function the same way.

Old supplies emphasized the +5 V rail over the +12 V rail, as your supplies' specs indicate. This means that the available +12 V current is not much by modern standards; by way of comparison, this unassuming 350 W supply has a combined +12 V rating of 28 A. This is especially a problem since it means that you very well may have problems with cross-loading, which will cause the output voltages to drift out of spec.

It gets worse, though. 13 year old power supplies have 13 year old capacitors, and capacitors only get worse with age. So your parts may not be able to deliver nearly as much power as they once could.

Oh, and to the best of my understanding most redundant power set-ups only run one power supply at a time, and bring up another one if the first fails.

I can't imagine this being worth the time needed to get it working.
 
Wow, thanks for the detailed reply Aluvus. I guess I'm just gonna strip the fans off these things and take them to the dump. Oh well. :/
 
I agree with Aluvus about the capacitors and the way redundant PSUs work.

Also 16Amps on the 12v rail is way too low. In most modern ATX mobos's manuals it's written it needs AT LEAST 18Amps for normal operation.
And i am 99,999% sure those will run out of specs.
 
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