It depends on you what you want to do, but I love messing around with computers and would find this as a chance to work on something that if it all goes pearshape you have lost nothing but you may gain some knowledge .
I would go out and buy a CHEAP GENERIC power supply and put it in, if it works thats terrific you have your computer back.
If it doesn't you have only lost a few dollars (you can save the power supply as a spare test one.
One minute with that meter would teach that answer. What is always required to have an informed answer? The 'why'. Very little changes in a computer over ten years. Mostly it only becomes faster. What you learn from this old computer applies to your every new computer and to computers even five years from now. Much of what was in the original IBM PC is still in your computers – simply upgraded.
To answer your question without learning why: disconnect the power cord from a wall receptacle if you swap or disconnect anything. Nothing in there will harm you. But not disconnecting AC may mean more hardware damage.
Learning technology would also expose that UPS recommendation as completely bogus. An example of what so many know only because they believe what they were ordered to believe. Never learned the underlying technology - the reasons 'why'. A typical UPS is no buffer. It connects a computer directly to AC mains when not in battery backup mode. It does not even claim effective protection in its numeric specs. Examples of why so many only know popular myths due to not learning facts - especially the numbers. Where is the number for that UPS that claims hardware protection? Will never be provided because that recommendation is based in hearsay. Wild speculation popular because so many never learn the underlying facts – the reasons why.
You can learn far more with a meter than if buying anything else - even a cheap power supply. The number one reason for fixing something was never to save money. #1 reason - to learn.
Well, I have to disagree with you there. A UPS is one of the best AC surge/ripple filters there is, in most cases. "Why?" you ask? Without getting into a long discussion on electrical theory and circuitry, it's because with most of the good ones, the AC is basically "strapped" across the battery. Normally, the incoming AC is converted (rectified) into DC, where it charges the battery. That voltage is then converted back to AC to run the computer and anything else plugged into it. Manufacturers do this to reduce the complexity of the UPS. Why have two filter systems, and two separate voltage paths? Using the already existing circuitry gives the added bonus of surge and ripple protection. Batteries are great levelers of ripple and surge current. Hardly "bogus", if you ask me.
And, btw, nothing relatively affordable can protect you from a close lightning strike. Particularly if it hits nearby power lines, or the AC wiring in the house. Even with a really good UPS or surge protector, you can probably kiss your electronic items goodbye. These things are not designed to protect against lightning. They are made to protect against occasional surges and spikes on the power grid.
Handing someone who has no practical electrical knowledge a meter is like handing the keys to a car to someone who has never driven one. No offense meant to the OP here, but he has already expressed concerns about getting a shock from his machine if he opens it. That suggests to me that he doesn't know a lot about electricity, and is nervous about it. There's nothing wrong with that, at all. I wish more people were more cautious with electricity. What is the OP really going to get from measuring his dead PSU? What if the lightning shorted something in the PSU, and put AC on the 12V rail? Someone untrained, or inexperienced could find themselves with a nasty shock, and your instructions earlier in the thread are incorrect. You forgot to tell him to ground the meter, rendering any measurements that are taken completely worthless.You can learn far more with a meter than if buying anything else - even a cheap power supply. The number one reason for fixing something was never to save money. #1 reason - to learn.
Better advice has already been given by others, and myself. Try a different PSU, and if it still doesn't work, oh well. Maybe the data on the drives can be saved. If the OP wants to probe around inside his PC, then sure, but if he isn't comfortable, then asking a knowledgeable friend for some guidance and help would be better than the advice you've given him.
MellonHead,
I'm with you.
I also have a Bachelor of Science degree in Electrical Engineering.
I have worked for a company that made a primitive UPS, but still it did perform a filtering function although that was not the reason for building the product.
Last edited by karlsnooks; 24 May 2010 at 17:31. Reason: left out the "not"
First and foremost,, I agree about the whole multimeter bit with an inexperienced user. Just don't do it, if you don't feel comfortable.
The PSU is most likely bad as has been stated.
With the PC unplugged, You will want to pull components and check them for char marks. Trust me, electricity can do very strange things. I had a bad Video card that worked for about a year after a lightening strike that blew out my PSU, but then the system started Blue Screening,, when I checked the Video card, it had been hit also. I also lost my NIC on my laptop in that hit among other things.
It is a very good chance that the Hard Drives and data are fine. But again, electricity does strange things.
Replace PSU, and test, check other components with PC unplugged. You will be fine. You can do it,, just take your time and be observant of how things are put together. You may have to replace more or less than you think. Do not be surprised however, if you start having other issues down the road.
Mellon Head,
They can be worth their weight in gold if you're in an area (or a building) with electrical spikes/surges.
Do you mind me asking for your recommendation when one is only faced with protecting a personal computer system?
Last edited by karlsnooks; 24 May 2010 at 17:50. Reason: add name
Id seriously consider taking this to a repair shop where they have the tools to see whats still working and repair or replace components as needed.
Nothing is good enough protection when a direct hit from lightning is concerned save having the electrical device disconnected from the power source. Some places simply have the right conditions to attract lightning more than others.
When we installed the 24/7/365 Security Zone Systems for special areas at our facility understanding where, historically, lightning had struck in the past we had to do some site evaluations to setup the triangulating antenna system required to ensure no security zone was left uncovered.
We identified all the bldg's which would be of benefit to the triangulation and blanket of coverage and one bldg in particular got struck 2-3 times during the summer months each year. We had to use this bldg for a series of the antennae due to its location and the fact it was the tallest bldg.
We used a sacrificial series of masts which were quite a bit longer than our antenna array and grounded, the system worked quite well and gave us a buffer of protection.
We also used UPS systems to protect our computer based systems but as I already stated nothing is as well protected from a direct hit unless it is physically disconnected from the power source taking the hit. With that in mind our circuits were protected with MOV banks. An MOV is a Metal Oxide Varistor, see schematic.
Essentially an MOV needs very little excitation to employ and this removes the devices downstream from the working electrical circuit. MOV's are available for home circuit use and a reasonably good one costs around $20. I use MOV's where anything electronic is that I wish to give some buffer of protection to understanding nothing is as safe as not being connected but the MOV is a close second. Some very good surge protectors have an MOV built in as do high end UPS's.
Thanks all for this interesting thread.
To the OP - your call and hope things work out
“Give a man a fish; you have fed him for today. Teach a man to fish; and you have fed him for a lifetime”—Author unknown
