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PC Not Booting Until a Different Phase is Used?
2by4 asks: "I run at IT Dept for a small firm, our network room houses production &
development servers. Some machines are plugged straight into a strip with
no UPS. Here is the Mystery Problem: When the power glitches, the strip
machines go down, and some of these machine WILL NOT come up again until I switch
them to a new outlet. Once this happens, I can put them back on the original outlet
and they will work. Unplugging & replugging on same outlet is not enough. I have seen this on at least 5 machines so far, with independent confirmation. We can narrow the 'fix' to plugging into an outlet of a different phase (there are 3 separate 120v phases powering the room). The symptoms vary from no powerup, to frozen at the BIOS (depends on motherboard make), etc, but consistently, switching to a new phase fixes them. I tried the 'unplug-wait-&-replug' cycle, to no avail. Using a new outlet w/ a different phase is the only solution. Any theories? I assume the new phase is causing something to 'reset', but what? I can provide more details, but I am wondering if anyone has seen this before? I am completely and absolutely stumped. Our power is healthy, lightly loaded, evenly distributed and the power strips are new. I know I should have at least a simple UPS, but this mystery is causing me to lose sleep."
Unplug the machine, hold the power button for about 10 seconds, plug it back in. You really don't want your machine bouncing on/off during power problems. Either that or go get a cheap UPS.
Well, once the plug was unplugged from its socket, how does the capacitor remember what phase it was plugged in? It's just sitting there holding a DC charge, which of course has no phase to rememeber.
I generally have the same problem with this entire scenario. If the equipment is designed to work on one phase, once it is disconnected from the wall, how does it keep track of exactly where the sine way should peak? The only thing I can imagine is that there is a battery driven oscilllator whose phase is somehow compared to the line phase. In that case you'd want to pop the battery backing up the oscillator (the mobo battery?).
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
We just got a 30 amp circuit installed for a 3kv ups. The UPS once powered up had a "check building wiring" light on the back that came on and stayed on. The cheapy circuit tester indicated that the wiring was fine along with an electrician verifying that all the wiring from the panel to the outlet was correct. One more symptom of this area is that light bulbs blow out much more than normal, although the PCs have not had anything unusual happening.
We had the original electrician who installed the line back out to test. His voltmeter was showing about 20-30V between the neutral and ground. According to code (IANALE), these lines are supposed to be connected at the panel. Apparently without this connection, the two sides coming off the transformer can float in the voltage which may have been responsible for the light bulbs blowing. Once the neutral and ground were connected, the wiring fault light went out on the ups and everthing has since been fine.
SHORT RESPONSE: Have a licensed electrician check out your circuits.
As someone already said, when you have weird electrical problems, suspect the ground. Remember that ALL devices and connections on a computer system need to be connected to the same ground. The exception to this is Ethernet network connections, which are very well isolated.
Printers must be connected to the same ground, for example. Check the integrity of the ground; their should be low resistance, as measured with an ohmmeter after you have turned off the power, of course.
Also suspect that there is some weird voltage riding on the power. Is your power clean? The only way to check this is to look at it with an oscilloscope. Oscilloscopes make an instantaneous on-screen graph of the voltage.
All computers should be connected to battery backup power supplies, too of course.
Boy, talk about the long arm of coincidence. This just happened to me *last night* with my Replay TV. It wasn't showing any life whatsoever, but I checked other devices in the same outlet and they were getting power. So I figured the Replay TV was cooked. I pulled it out, and thinking I might try and fix it (i.e., kick the damn thing a few times) I plugged it into a different outlet and it worked just fine. I took it back to the original outlet, and it works just fine. This hardly answers your question, but another data point never hurts.
"My girlfriend's got sodium laureth sulfate hair."
I've run into this type of issue several times. The issue is'nt so much moving the plug, it's that the MB maintains power for up to a couple of minutes after the power is lost. If the Power glitched, the MB may be in a non-useable state. The way I solve the problem is this:
1) Unplug the Power supply.
2) Hold down the power button (on the front) for 10 seconds.
3) plug in the power supply
4) Turn on the computer.
I solve this issue with most of my systems by connectiong them to a UPS. Some crash on their own so often that they're not worth a UPS.
I worked as an electrician for a time (doesn't pay as much as programming, though :), and sometimes wierd problems can be traced to "loose neutrals". If you could open up a circuit-breaker box, you will see either 3 or 4 main "power" wires, distinct from the ground wire. 2 or 3 of them are actually your power lines, which feed the breakers (you have described a 3-phase system, so you must have 3), while the remaining line is the "neutral". Its purpose in a SINGLE-phase system is to return all the power brought to the load from a single power wire (completing the circuit), but in a two-phase or three-phase system, the neutral only carries the DIFFERENCE of the loads on the other wires. Well, if the neutral wire gets loose (and sometimes this happens in the breaker box, sometimes it happens where power enters the building (the meter), and sometimes it happens at the power company's transformer), all sorts of mysterious voltage swings happen on the main power wires, as different loads are switched on and off the various phases. These can be expected to adversely affect the power supplies in your PCs and servers. I don't know if the consequences include the particular problem described here, but as something to check (loose neutrals), I recommend it.
An electrician can also check the actual screws of the wires in the wall outlets (are they REALLY grounded like they should be?). If you can have "isolated ground" outlets installed, I would recommend that, too. Along with the usual surge suppressor and UPS equipment, of course.
Usually 3 phase outlets are completly different looking plugs. If that is the case. It could be that the a phase is on one side, and b phase is on the other side of a panel. I would go along with what other people have said. Power will get you without out you knowing. If you know what you are doing. Make sure the all the phases are good and tight. Especially the neutral. If you are using 3 pahse, you might read up on it a bit. That would make sense. (If you havent already). IF you have an electrician come in, then you can blame them. Besty 100$ OR so you will spend. If you think that you can do this on a couple of machines. Try different ones in different strips. Use a differnt extension cord to the wall. See if there is still your problem. It oculd be a loose grounhd or neutral in the strips themselves. Make sure that you follow the adivce in balancing the load. Not sure your production numbers. If you have 6 pcs, make sure that there is 2 in each phase. You get the idea. The other piece of useful stuff that you might use is a digital ammeter. This will tell you how much power that you are drawing on each leg. You can make sure that you are balanced. I'm sure that there are some that are digital and soime that even have a little pager-like gadget that goes with you. Then its easy. I work in the entertainment industry and I use phase all the time. The big movie lights are upwards or 12kw of light. Its very critical to balance the load. Especially for generators. The easiest way is to get some big worklights that you can plug in and leave on to balance it out. Im sure that there are others.
I have mod points and I am not afraid to use them.
My machine at work gets wonky after a power blip. It will not power up until I remove the plug from the wall (or flip the main switch on the PS) and hold the power button on the front of the case. I can actually hear a little squeak from the power supply that lets me know it is ready to go.
Actually I believe that it is Gremlins which are typically the cause of machine troubles. I even have a wikipedia link to back it up. http://en.wikipedia.org/wiki/Gremlin
Don't blame me, I voted for Cthulhu.
1) As other have pointed out, bad grounding on one or more phases.
2) Bad neutral on one or more phases.
3) Voltage drop on one or more phases.
For the first three get an electrician out, don't mess around with three-phase power.
4) Electrical noise on one or more phases, this may not be caused within your computer room.
5) Equipment connected on different phases affecting each other, for example a printer on phase A and a server on phase B.
6) Borderline power supply in a machine affected by one or more of the above conditions.
7) Faulty power strip(s).
8) Incorrectly wired plug(s) or socket(s).
Ed Almos
The more corrupt the state, the more numerous the laws. - Tacitus, 56-120 A.D.
Your parents must have very very unusual power. Three phase power is hardly ever found in houses. In the US, we don't even have two phase power - we use a single split phase.
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
If you have 220 in the house (typically for an electric stove or a clothes dryer), you have two phase coming in from the street.
Not really. House 240V power is created by connecting one phase of a three phase feed to a transformer with a center tapped output. The center tap is grounded and voila, you get split phase 240V power. It consists of a ground, plus one leg at +120V and the other at -120V, referenced to ground of course. Take the potential across the two of them and you get 240V. While these legs are separated in phase by Pi radians, this is not what is referred to as two phase power.
"Nature doesn't care how smart you are. You can still be wrong." - Richard Feynman
I'm not an EE (and only have the absolute basic knowledge of electronics), so I can't really meaningfully elaborate further.
I used up all my sick days, so I'm calling in dead.