PC Power Supply Swap?

Why not take the chance? Go for it

I've noticed that printer cables used to have a couple of pins reversed, so that you had to buy the proprietary version, and don't want to take chances with power, not data. Also, the old supply has the on/off switch on it, while the "new" one has a remote switch.

Thanks for all replies.

As long as there are all the same connectors, then yes it may work.

Proviso being that nothing on the mother board was fragged as a result of the previous supply failing.

The other proviso being that the previous supply wasn't operating at or near its limits in providing power to the computer.

You would usually replace the failed supply with one of equal or greater capacity. That would be my choice, however as you have the smaller supply already, then I'd start by stripping the computer out, leaving the bare essentials and then adding the extras in.

I.E. Just have the mother board and video card power up with the "new" supply. If the mother board "posts" and you get a display on the monitor your good for the next step. Turn off the computer allow a minute for the supply to discharge, and fit the hard drive. Turn the computer on and see if it "boots".

If that's all good, I'd continue to add bits selectively but be careful, in puter terms 250watts is not very big, I'd be looking for a 400watt supply if I've got a fancy graphics card and a couple of hard drives.

Better go and get yourself a surge protector power board too, might save you in the next storm.

hello,

why should you not try?????and tell us what is happen whether it is working or not.

i think nothing will happens if you say the connectors are same but before connecting you should also confirm about the power rating, voltage rating, current rating and if it has large difference then not going to try because it is dangerous

Gee, you have shared a lot in your post.

I would suspect the odds of success will vary inversely with the price of the PC.

That is to say, if your computer was inexpensive, it will probably be fine. If the PC was thousands of dollars, the smoke released when hooked up to the incorrect power supply must be captured and reinstalled.

What testing have you done to confirm the correct power supply is inoperative?

I have not done any testing on the dead computer. It belongs to a friend, who never expected to have it on during a storm. It has booted up once since that day. I'm interested in trying it with my own old power supply because the nearest recommended service tech is 2 hours away, and several people have said that the power supply is the most likely problem. Only the replacement power supply lists the output according to wire color. Everything is at least seven years old.

If you have access to a working computer try an internet search for the manuals or pin layouts for the two power supplies to ensure compatibility.

Generally they are all of a standardised design and have the same pin configurations, however your old power supply may not have the right (newer standard) connector plugs or sockets (or too few of them), if that is the case it will be obvious that it is incompatible.

Have a look at the plugs and see if they look the same and there are enough of them.

Generally the power switch style doesn't matter, however it is unlikely that an older style power supply with a big clunky fixed switch will physically fit in a modern computer case (this may in fact be your biggest problem).

before replacing the power supply , put a multimeter / voltmeter on the old one and see if it has output

also check if there is a fuse on , or inside the old power supply , if you can replace a fuse then use the bigger 300 watt PS is better.

if you have power coming out of the power supply but computer wont boot , then the board could be fried , i am vegetarian , so i cant suggest what to have with the fried motherboard, maybe steamed veges ;)

i saw a PC that was lightning struck , and everything was fried , motherboard , memory and HDD , if you have a phone line connected to it , they can be killed by that route too , not just from the mains power connection

the poster above who recommended surge protection is right , its a good investment , for $ 140 - 200 you can plug in printer , modem , PC , LCD TV , and most of them have facility to protect the phone cable end as well

dont buy the cheap ones !

That probably won't work to check either the old or the new power supply. The switch-mode supplies used in PCs need some level of load on them before you can get a valid, proper output level. So putting a meter on the outputs probably won't tell you anything about them.

As for replacing the 300W with a 250W, the brands he mentioned are standard, generic brands (rather than a specific PC manufacturer's brand such as Dell), so you can be 99.9% sure if the cable connectors are the same (and wire colors probably too), they are interchangeable there. As for the wattage, unless you have loaded the PC up with lots of extra peripheral cards, the difference in the PS's capacity shouldn't matter, at least to see if it works after the storm. Still, I'd go with a permanent replacement the same or greater wattage.

For this reason cooling fan is hard-wired to give some load to PC supplies.

You can test it [all the connectors [20+4]. Shorting pin #14 [Green] to any black nearby, [13 or 15] will start the supply and running of fan indicates that +12V is ok.

Yup, worst case scenario you won't have the right connections to power everything up and/or you wont have enough juice to run everything. In which you won't have enough juice to hurt anything either!

Insufficient power and/or voltage is just as bad for electronics as it is for motors. It could burn out the electronics. Low voltage causes components to build up more heat, thus cooking the chips. I would not, under any circumstances, try to use a power supply that could not provide the same amount of power as the original. It is very doubtful that a computer manufacturer would spend the money to put in an oversized power supply. They usually cut those as close as possible.

I have heard it said: "computer chips run on 'smoke', and if it ever gets out, then they won't work anymore".

Let's just hope, that you don't see any smoke.

Hmm. There IS a strong, smoky smell inside the case. I had put it down to the wood-heated cabin where it lived and languished, since it does smell just like wood smoke, not the magic smoke formula used by Lucas or Zenith. Does silicon, etc, fry with a distinctive odor?

Sure does. Bakelite (phenolic) and epoxy both give off a very distinctive smell that is nothing like wood smoke.

Being an ex computer tech plugging in lower rated power supplies (PS) doesn't (really sort of -hedging the bet ) matter - it just might not drive thing as well as it could. As Tobugrynbak says try with just the video card and M/board and go on... --As a side not-- a number of years ago you could bulk buy from the asian market computer PS's at any wattage you wanted, they would give you the stickers to match your request.

First thing to do is determine if PS is working. Further to that if you know a little about electrickery, check the outputs on the ps with a multimeter, don't forget to load the PS ie plug in the power to the drives - This will also tell you if you PS is working -If no power rip the lid of the PS and check the fuse, that is after you unplugged the litter bugger from the mains power. IF the fuse is gone replace - if not then you're best bet is to bin it.

With some computers I've had the 'pleasure' to work on fritzed mother boards have 'pulled' the PS down and it will act as dead even though it is operational under normal conditions

In trying to swap one PS for another you may have the problem of mismatched connectors. There has been a number of changes in the connectors from PS's over such a short time. So as long as the connectors are same/similar you should be alright. Some manufactures of PS have been known to use two or three connectors whilst the majority use one.

sorry realised I've wandered around abit -upshot give it ago - especially if you ks away from help.

Good Answer

I would have phrased the last sentence the other way round:-

You can check to see if either of the power supplies is working by shorting pin 14 to ground (pin 13 or 15).

Wow, I almost hate to throw in my two cents worth but I picked up on one thing and that was it booted once since the thunderstorm. That leads me to suggest that you look at the capacitors. They are the little things that look like miniature pop cans with a stripe down the side. (usually)

The tops of them are plain aluminum usually with a "X" stamped into them. The tops should be flat. Look to see if they are swelled up in which case the tops will be rounded up and possibly leaking a brownish fluid. If you find that's the case a new motherboard is usually cheaper than replacing the bad capacitors or tell your friend he's really gotten his moneys worth and it's time to buy a new machine.

Good luck,

Randy

Thanks, that sounds like a handy tip, although all these look healthy. A friend of mine used to be a whiz at diagnosing mainframes. His edge was a cheap transistor radio, and knowing what kind of interference it usually picked up around each area of a healthy machine. Looping components, of course, were quite obvious.

LOL! I used to do that too! You can hear the machine functioning at those frequencies and by the regular pattern of sounds the components produce.

My hearing aid has a "telephone" mode that uses a pickup coil and serves the same purpose. I can "hear" the electronics of a harddrive or a CPU or memory etc. depending on which one I get my ear close too.

By pure coincidence: I just came across this:-

http://en.wikipedia.org/wiki/Capacitor_plague

Athough power supplies are rated in watts, that can be a little foggy at best. Check and see how many amps they are rated for 5 and 12 volts. I would bet they are pretty similar. The Antec claims 300 watt rating, but it's spec sheet shows only 220 watts. http://www.antec.com/ I can't find info on the Karpo, but it should be on the power supply itself. I've never known power supplies with identical connectors to be wired differently, so if the connector fits you'll be fine.

I did go down the lists of amperages at each voltage, and they are all reduced, somewhat unevenly but never radically.

It was some 20/25 years back in 486 time. I have experienced the connections and color codes variety, but cannot be expected in 2011.

Rating compatibilly is a must.

Swapping the power unit out will not be a problem, the wattage difference means it has less power but you have enough to run a normal PC - 2 HDs, DVD, etc.

If you had a power failure, have you checked the fuses?

There isn't a video accelerator card in the PSU, I'm not sure what you mean by this, the video card is in the PC

The supplies and plugs are designed to be correct if they plug in ok. You will have a 20 pin or a 24 pin connector to the motherboard. That's the main cable. The 24 pin connector is identical to the 20 with four extra connections on one end for extra current.

There may be a four pin connector that plugs in next to the CPU. That too is for extra current. So if you had a 300w supply, and the replacement is a 250, and the connectors are the same, then it will work.

The draw back is the current loading. If the machine uses more than 250w, like when running a game/graphics/GPU, then you may fry the replacement. But most machines will draw only 150-200w in normal operation.

The switch on the back of one supply is for total power off. Not all supplies have this, but it is no different than pulling the plug. Makes no difference.

Go ahead and hook it up. 250w is enough for any single CPU and single harddrive machine. Use it if it works and order up a 400 for it while you do.

I've seen Dell's & HP's that had the pins arranged in a slightly different configurations

I simply spliced the connector that goes with the mother board on to the PSU I wanted to use

the 4 wire yellow & black should also be checked for arrangement

some motherboards have a 2wire connection for a temp probe inside the PSU, which can usually be jumped, do a search to make sure

He's probably not got one of those. Those PSs are shaped and sized differently from from the standard clone type supplies.

So if he has a 250 that fits and has the same connectors as his 300, he's probably good to go.

You're probably right

my point is hold the connectors up side by side & do a quick pin by pin comparison

watch out for any small odd 2 wire connectors coming out of the psu

I posted the additional info, after looking at the title, which is general enough to come up in searches...

I have had both small form factor & full sized HP's with unique atx PSU 20 pin connectors pin layouts. The full sized HP PSU looks like any other clone PSU

I went ahead and swapped the power supply, and had to wait for my friend to plug in to the fancy video card. The only change now is that it loops. When you turn it on, it boots up until it is ready for the 1st mouse click, with the pointer moving, etc, and then it re-boots again. Formerly, it only did that once per toggle switch. Anyone recognize the symptoms? Thanks,

Yes, it's an HP 1000 series printer, right? Unplug the printer from the USB and see if the looping stops.

Uninstall the drivers/crapware in safe mode if you can, and re-install later when the system is stable and updated.

No, there's no printer involved. The machine is running in Windows "safe" mode, and still looping the whole boot-up.

If you have the windows CD, boot that in recovery mode, and run "fixmbr" and "fixboot". Then try safe mode again with command prompt only. see if you can get it to run "msconfig" and if so, choose diagnostic startup.

If that then gets it to the desktop, run the updates on your anti virus and run a full scan. Open msconfig again and look for startup items that don't look right or have "unknown" as the vendor and remove them from the startup using "selective startup" mode instead of "diagnostic startup" mode.

Basically, what you have is a bum driver or more likely a bum system tray app that is failing and rebooting the system. Otherwise, you have a damaged device that is failing when the driver loads.

ooh good stuff

advanced tricks, for start up

what would you do without the CD?

Without the CD, You can boot a Linux Live CD and scan using Avast or ClamAV. There are also tools like UBCD that contain linux based registry editor so you can manually disable startups and drivers.

I usually install Linux in dual boot mode on Windows machines so that I can manipulate the Windows filesystem without Windows and it's infection(s) booting up. I delete all temp directory contents in all the temp directories, dump the pagefile.sys file, and run a full virus scan from the Linux Desktop, and then reboot into Windows and run a full scan again. I can also download utilities that are blocked by active infections in Windows and then I have them on the disk to install and run when Windows is restarted.

If the network is connected when running Linux, I will disconnect it when rebooting to Windows, so that the infection cannot download and replace any of it's parts that are missing after I dump the Temp directories contents. Now the infection is probably in limbo, partially running, but unable to update the rest of its code.

I run Linux day to day

I have a few different distros on USB flash drives as self contained operating systems, which are nice

fully updated with what ever apps I like to use

Me too. SUSE on my servers and Ubuntu on everything else pretty much. I like Maverick better than Natty. Unity is a bit much right now, and so I stick to Gnome2 and KDE3.

I setup an Acer Aspire One with ChromeOS and it's very nice!

I've been playing around with

the mandriva fork

http://www.mageia.org/en/

the fork happened because mandriva decided to concentrate on the server market & let most of the developers go

the situation reminds me of the open office, libre office

I went distro shopping because of Unity

I'm staying with 10.10 at least until the next LTS comes out

Is it blue screening before it reboots? If so possibly corrupted OS.

If it has a modem (dial-up) remove and try again. We loved thunder storms...sold modems by the gazillions in early-mid 2000's

Did you check capacitors? See #13.

Check memory.

Carefully look for any burned components.

clean dust balls from behind motherboard.