Flashing computer screen

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Re: Flashing computer screen

Another thought: if the house has knob and tube wiring you will have a high magnetic field from the circuits due to separation of conductors. In that case re-wire or move the computer away from any circuit runs in the wall, floor, etc.

Karl
 
Re: Flashing computer screen

If you are going to install IG receptacle do not use MC cable you need to use HCF cable.
I would not myself install IG receptacle. I would just make sure it's on it's own circuit.
 
Re: Flashing computer screen

All the previous posts that I read here are sound advice, especially the dedicated circuits for both microwave and computer/monitor. It would be helpful to bring a surge suppression power strip w/ a hi-end filter attached (do not cut corners with the price). Isolation of the computer circuit is mandatory, the symptoms you are describing will lead to loss of data on the hard drive. Act fast!
 
Re: Flashing computer screen

Would suggest a small USP for the computer if circuit must be shared but a good ground would be needed first.In Fl a USP is almost a must with our lightning and surges from it.They can be bought for about $125 at sams.
 
Re: Flashing computer screen

Jim, I suspect a UPS in this price catagorie would be a standby type, and offer no vlotage regulation or line conditioning. In other words a stanby-UPS just sits there passively until it senses a complete power outage, then turns on.

You would have to use a line-interactive or dual conversion UPS to offer any type of voltage regulation or line conditioning.
 
Re: Flashing computer screen

Ok I went to the job in person today and this is what I found: Computer screen shakes when the AC runs as well as the micro. There is no gnd on the micro or the computer circ as they are the same circ. Yes there are 3wire plugs in both. The AC unit sits just outside opposite of the computer monitor. It seems to me that the micro being on the same circ. is causing that problem. Now what about the AC will a new dedicated grounded circ. fix that problem, it's probably picking up EMF from it as it is only 5' away on the other side of the wall. Correct? The AC unit is 240v 40a circ.

Now for the seperate part of the problem the panel is FPE stablock breakers type nc. I heard they lost thier UL listing due to not tripping, Is this true? Are they available? Would it be wrong to put a sub panel off it.(there is a 40a spare)
Thanks
 
Re: Flashing computer screen

Originally posted by jes25:
Ok I went to the job in person today and this is what I found: Computer screen shakes when the AC runs as well as the micro. There is no gnd on the micro or the computer circ as they are the same circ. Yes there are 3wire plugs in both. The AC unit sits just outside opposite of the computer monitor. It seems to me that the micro being on the same circ. is causing that problem. Now what about the AC will a new dedicated grounded circ. fix that problem, it's probably picking up EMF from it as it is only 5' away on the other side of the wall. Correct? The AC unit is 240v 40a circ.

Now for the seperate part of the problem the panel is FPE stablock breakers type nc. I heard they lost thier UL listing due to not tripping, Is this true? Are they available? Would it be wrong to put a sub panel off it.(there is a 40a spare)
Thanks
Click to expand...
jes25, I am I understanding the situation correctly. You have a 240V/40A A/C unit connected to the same circuit as the computer?
 
Re: Flashing computer screen

No, I have the micro on the computer circuit. The 240v 40a AC is on its own circuit but the condeser sits only five feet away from the computer because the computer is on the outside wall.
 
Re: Flashing computer screen

Jes25, A dedicated micro and AC circuit will correct the problem. Just for clarification, an EGC has nothing to do with the problem IMO.

You can run a dedicated circuit for the PC, but I do not think it is nesecary. What is important is the AC and micro.
 
Re: Flashing computer screen

It seems to me that the micro being on the same circ. is causing that problem.

How is that? It seems to me that the AC unit is also causing the same problem. Kind of against the laws of probability that such different items would cause the exact same problem. You have to find a common thread. I seriously doubt that this is due to a EMF by the way. Anytime you suspect EMF problems with computer monitors simply pick it up and move it around. If the problem is actually caused by an EMF the symptoms will change, if not look elsewhere. The lack of grounds shouldn't make any difference either.

Keep looking before you start changing things around and costing the customer money. Get an extension cord from your truck and use it to power the computer and monitor from other places in the house. That should tell you if another circuit will take care of the problem. Contrary to popular belief computers do NOT have to be on dedicated circuits these days and certainly not with iso grounds.

Also, one of the most important steps in troubleshooting is also the simplest. Find out when this started happening! THEN ask what, if anything, was also going on at the same time. Repairs in the house, thunder storm, lights dimming, power outage- ANYTHING can give you a big clue as to what to look for and where to look. ASK QUESTIONS!

-Hal
 
Re: Flashing computer screen

Pluging the computer into another circuit fixes the problem. I just dont know why and that bothers me.
 
Re: Flashing computer screen

Already looked at that circuit. Everthing looks fine except for the FPE breakers and lack of EGC. (I think we determined these two problems are irrelevant) MY concern is this I get a new circuit up to the computer and the problem is fixed but without really knowing the cause I feel like I put a band aid on a real problem that could possibly lead to a fire or something.

:confused:

[ June 15, 2004, 08:19 PM: Message edited by: jes25 ]
 
Re: Flashing computer screen

Could be that the new circuit that you plugged the computer into to test it is on a different phase than the original microwave/computer circuit. Could also be that one side of the service is loose or corroded. The load from the microwave or the AC could be causing that side to sag. Like I said, look for a common denominator.

-Hal
 
Re: Flashing computer screen

Originally posted by hbiss:
It seems to me that the micro being on the same circ. is causing that problem.

Contrary to popular belief computers do NOT have to be on dedicated circuits these days and certainly not with iso grounds.

-Hal
Click to expand...
Hal,

I strongly disagree with the part of this statement that pertains to dedication of the computer circuit. The initial surge on start up demand of an AC or motor related item can cause extensive damage to the hard drive of the system when on the same circuit. The momentary voltage drop is devastating to the magnetic field that the hard drive operates on. Your data could be lost in oblivion due to this aspect. Please take my word for this!

Is the problem with flashing on the screen only visible when the condenser is operational as opposed to standby? Try this test, plug an extension cord to the SAME receptacle that the computer/monitor is currently on, and take them to another area away from the condenser. I have seen another monitor in close proximity cause all types of strange behavior to a monitor's display.
 
Re: Flashing computer screen

The momentary voltage drop is devastating...

That's why computers use a regulated power supply. If the voltage drop is so bad that the supply cannot compensate for it then there are other problems that need to be addressed. One solution is a UPS.

True enough, I wouldn't put a 24,000 BTU air conditioner on the same circuit but that doesn't mean that if the circuit is adequate you can't have other equipment sharing it. Most times problems like this are because of poor wiring or overloaded circuits.


-Hal
 
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