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Fire-Flare
April 21st, 2011, 01:58 PM
Greetings, I'm retrofitting a dead IBM 5150 to use modern hardware and I want it to appear stock from the outside.

With that in mind, the biggest complication is the power switch. Will splicing the green and black wire onto the original 'switch' damage a modern PSU or attached components since they expect a momentary button press?

Also, do modern operating systems support manual shut-down?

Ole Juul
April 21st, 2011, 02:29 PM
I don't have a PS in front of me to check the colours, but ... with common AC the green is ground and the black is power.

modem7
April 21st, 2011, 02:57 PM
In a modern PC, the chassis power switch is momentary-action and is connected to the motherboard.
The motherboard grounds the green wire of the ATX PSU when it wants the ATX PSU to suppy power.

OPTION 1 - MANUAL

You would connect the green/black wires of the ATX PSU to the old red switch on the old PSU.
So instead of the motherboard controlling ATX power, it's the red switch.
The shutdown sequence would be to shut down the modern OS then turn off the red switch.

OPTION 2 - LIKE MODERN PC

Alternatively, you could let the motherboard control ATX power, and use the red switch on the old PSU as a substitute for the momentary-action chassis power switch.
The startup sequence would be to quickly flip up/down the red switch.
The shutdown sequence would be to either:
1. Shut down via the modern OS, or
2. Quickly flip up/down the red switch.

You would have to remember not to leave the red switch in the up position.

lutiana
April 21st, 2011, 04:02 PM
Greetings, I'm retrofitting a dead IBM 5150 to use modern hardware and I want it to appear stock from the outside.

With that in mind, the biggest complication is the power switch. Will splicing the green and black wire onto the original 'switch' damage a modern PSU or attached components since they expect a momentary button press?

Also, do modern operating systems support manual shut-down?

In ATX machines (modern machines) the PSU is turned on by the motherboard. The board simply grounds the green wire coming from the PSU to turn it on and ungrounds it to turn it off. In old machines (Pre-ATX) the power was controlled directly (hence the thick wires that come from the PSU to the switch).

You could cut the green wire from the ATX connectlor and wire it into the power switch on the side of the case and I don't think you will have any issues other than the fact that the computer could not turn the PSU off, it would need to be done manually. I am not sure what would happen if you shut down an ACPI compliant OS in this situation, it may halt the system for you to kill the power, but it may also simply reboot after the shutdown procedure. There really is only one way to find out and that is to try it, it certainly won't damage anything.

jetmike747
April 21st, 2011, 05:26 PM
I used to have an old ATX motherboard that was a pentium 2. You would turn it on like a modern ATX machine, but when you turn it off, it would go into the normal XP shutdown procedure, and when the time came where the PSU would normally shutoff it would say "It is now safe to turn off your computer". Then you just touch the power button and it'd shut off. Maybe the same will happen with a newer motherboard? I guess the old motherboard wasn't capable of shutting the PSU off.

lutiana
April 21st, 2011, 05:51 PM
I used to have an old ATX motherboard that was a pentium 2. You would turn it on like a modern ATX machine, but when you turn it off, it would go into the normal XP shutdown procedure, and when the time came where the PSU would normally shutoff it would say "It is now safe to turn off your computer". Then you just touch the power button and it'd shut off. Maybe the same will happen with a newer motherboard? I guess the old motherboard wasn't capable of shutting the PSU off.


That was because you had the wrong HAL installed for XP, probably the standard PC HAL (versus the ACPI PC HAL), I am guessing no other power features worked (sleep mode for eg). It also could have been from some BIOS settings to do with power. In any event I would not recommend disabeling the power features in a modern machine as it will effect cooling and power consumption (and your electric bill).

jetmike747
April 21st, 2011, 05:56 PM
That was because you had the wrong HAL installed for XP, probably the standard PC HAL (versus the ACPI PC HAL), I am guessing no other power features worked (sleep mode for eg). It also could have been from some BIOS settings to do with power. In any event I would not recommend disabeling the power features in a modern machine as it will effect cooling and power consumption (and your electric bill).

I learn something new almost everyday from this site lol.

lutiana
April 21st, 2011, 06:53 PM
I learn something new almost everyday from this site lol.

As do I!

MikeS
April 22nd, 2011, 09:50 AM
You could cut the green wire from the ATX connectlor and wire it into the power switch on the side of the case and I don't think you will have any issues other than the fact that the computer could not turn the PSU off, it would need to be done manually. I am not sure what would happen if you shut down an ACPI compliant OS in this situation, it may halt the system for you to kill the power, but it may also simply reboot after the shutdown procedure. There really is only one way to find out and that is to try it, it certainly won't damage anything.Why not just ground the green wire permanently and use the Big Red Switch to turn the AC power on/off the way it was originally? Also eliminates the stand-by power drain and helps to avoid inserting memory chips, etc. with standby power still on; in fact, many ATX supplies did have an AC main on/off switch.

At least every version of Windows I've seen had manual shutdown options: the 'Start' button of course ;-)

lutiana
April 22nd, 2011, 10:00 AM
Why not just ground the green wire permanently and use the Big Red Switch to turn the AC power on/off the way it was originally? Also eliminates the stand-by power drain; in fact, many ATX supplies did have an AC main on/off switch.

At least every version of Windows I've seen had manual shutdown options: the 'Start' button of course ;-)

That would work, but it does mean playing with AC wiring. My suggestion is a bit safer ;D

I still wonder what the machine will do when you initiate the shutdown after everything is killed. In most PCs the last thing it does is actually tell the PSU to turn off, but in this case that signal is ignored so the MB will continue to get power and I am not sure what it will do in this case. Ideally it will do nothing and you can kill the power, but I suspect there is a possibility that the MB will simply reset and before you know it you are back at the desktop.

Hopefully the OP will report back and let us know, otherwise I may need to do an experiment at some point.

Chuck(G)
April 22nd, 2011, 11:10 AM
ATX supplies made for industrial use often have a separate AC switch due to safety considerations. That is, there's a requirement for power to be positively "off" lest the equipment be accidentally powered up (anytime that power is controlled by software, you have that issue). I have such a supply--looks like a plain-Jane ATX supply, but has a cable coming out for an external AC switch.

Since you're re-housing the ATX PSU "guts" to fit the PC, there's no downside for making the BRS switch the AC line.

Fire-Flare
April 22nd, 2011, 11:16 AM
Why not just ground the green wire permanently and use the Big Red Switch to turn the AC power on/off the way it was originally? Also eliminates the stand-by power drain and helps to avoid inserting memory chips, etc. with standby power still on; in fact, many ATX supplies did have an AC main on/off switch.

At least every version of Windows I've seen had manual shutdown options: the 'Start' button of course ;-)

Because I didn't think of it, thanks!

And the Start button brings up the shutdown menu, but it's not what I meant. The shutdown sequence parks the drive heads, unloads the temp files, and ends all the programs; but the final step is either an automatic kill command to the power supply or displaying the phrase, "IT IS NOW SAFE TO TURN OFF YOUR COMPUTER"

MikeS
April 22nd, 2011, 12:57 PM
Because I didn't think of it, thanks!

And the Start button brings up the shutdown menu, but it's not what I meant. The shutdown sequence parks the drive heads, unloads the temp files, and ends all the programs; but the final step is either an automatic kill command to the power supply or displaying the phrase, "IT IS NOW SAFE TO TURN OFF YOUR COMPUTER"Well, that's what the Big Red Switch is for! You are shooting for retro, right?

MikeS
April 22nd, 2011, 02:05 PM
That would work, but it does mean playing with AC wiring. My suggestion is a bit safer ;DTrue enough, but depending on how the OP installs the supply leaving TBRS in place he may have to deal with the AC side anyway.


I still wonder what the machine will do when you initiate the shutdown after everything is killed. In most PCs the last thing it does is actually tell the PSU to turn off, but in this case that signal is ignored so the MB will continue to get power and I am not sure what it will do in this case. Ideally it will do nothing and you can kill the power, but I suspect there is a possibility that the MB will simply reset and before you know it you are back at the desktop.Yeah, I was wondering about that; I suspect that it won't, but definitely worth investigating.
Hopefully the OP will report back and let us know, otherwise I may need to do an experiment at some point.By all means, do it and let us know. ;-)

But one other thing to consider: many BIOSes have an option to select an unattended restart after a power shutdown/failure, and I think at least some of the supplies that have a main switch also start up automatically when power is applied; I just fired up a couple of IBM boards and they started right up without pressing any button.

My preference would still be to switch the main power, unless you need standby power for anything.

Chuck(G)
April 22nd, 2011, 02:35 PM
Except for those units with a real AC power switch, an ATX PSU never turns off--there's always 5v present on the motherboard connector on at least one of the pins. It's sort of like your LCD display--you don't think that little button on the front switches the AC line do you?

MikeS
April 22nd, 2011, 05:42 PM
Except for those units with a real AC power switch, an ATX PSU never turns off--there's always 5v present on the motherboard connector on at least one of the pins. It's sort of like your LCD display--you don't think that little button on the front switches the AC line do you?Yeah, apparently standby or 'Vampire' power accounts for 5-10% or more of the average household consumption and 'they' want us all to use power bars to turn off our wasteful equipment; they don't offer to come around and reset all our clocks and timers every time though... ;-)

Chuck(G)
April 22nd, 2011, 06:11 PM
Yeah, apparently standby or 'Vampire' power accounts for 5-10% or more of the average household consumption and 'they' want us all to use power bars to turn off our wasteful equipment; they don't offer to come around and reset all our clocks and timers every time though... ;-)

Yeah, but the funny thing is that few pieces of the aforementioned equipment have any sort of "real off" switch. So it's up to you to spend money on power strips and the like (and then figure somewhere to put them that they won't get in the way.

And of course, no "wall wart" has an AC power switch--and those bloody things are all over the place, sipping power even when they're "off".

Are there any adapters to fit over a wall outlet that provide "full off" functionality without the bother of the cord of a power strip?

It's really bizarre--the US is hot on the trend to discontinue sales of incandescent lamps, yet regulators do nothing about the issue of vampire power.

Jorg
April 22nd, 2011, 09:33 PM
I'm using one of there, two connectors going to an on/off switch

http://media.technik-ass.de/IE-26641S.jpg