gillies@p.cs.uiuc.edu (06/06/89)
Here's a question I'm curious about: What can a consistently too low/high-voltage wall socket (100/140 volts instead of 120, for instance) cause a PC power supply to do to the rest of the computer? How can erratic frequency control change the supply, and in turn, affect the computer? Someone in comp.sys.mac has had 10 separate problems with their Mac/SE (5 disk drives, 2 system boards, 2 keyboards, 1 mouse). Many users have no problems at all. I'm curious if the power outlet in their dorm room might be a partial culprit. Don Gillies, Dept. of Computer Science, University of Illinois 1304 W. Springfield, Urbana, Ill 61801 ARPA: gillies@cs.uiuc.edu UUCP: {uunet,harvard}!uiucdcs!gillies
Ploni.Almoni@mailcom.FIDONET.ORG (Ploni Almoni) (06/13/89)
Don - re your problem of "outlet voltage" varying from 100 - 150 V This is a well known, SERIOUS and DANGEROUS problem. It is NOT good for the power supply and will eventually lead to premature and catastrophic failure. To say nothing of what the line surges will do to your data!! It is caused by an ungrounded neutral - a code violation as well as a safety hazard. In a 120/240 V service, the power utility supplies 120 V each side of a grounded neutral. This grounded neutral (the "white wire" in the cable or the "elongated slot" in the outlet) is supposed to be a solid, reliable connection and extended throughout the installation. However, if the neutral in the particular circuit (group of outlets, for instance) becomes isolated from the entrance grounded neutral, the 120 V loads stacked in series between the two "hot" lines will not receive 120 V. What they will receive between the "hot" line and the UNgrounded neutral depends on the balance of the loads between the two "sides" of the 240/120 circuit - in that case the only "given" is the 240 V "line-to-line". If the loads are balanced, the line-to-neutral voltages will be approximately correct. If the loads are unbalanced, one side will get a high voltage while the other will get a low voltage. And as the balance shifts (as stuff is turned on and off, for instance), the voltage will go up and down. 90/150 V is not unusual. This problem has been the cause of an awful lot of "appliance frying" over the years. It also results in improper operation ( = failure to protect) of Ground Fault Interrupters, a specific safety device. And it can cause shock hazards on equipment plugged into those lines. QUICK - get the house electrician to check the breaker panels and entrance equipment to see if a "white wire" has broken or come loose from the neutral bus. Your computer's life - or YOUR life - may depend on it. -=Ploni=- -- Via apple!mailcom, Fido 1:204/444
myers@hpfcdj.HP.COM (Bob Myers) (06/17/89)
>This is a well known, SERIOUS and DANGEROUS problem. It is NOT good >for the power supply and will eventually lead to premature and >catastrophic failure. To say nothing of what the line surges will do >to your data!! >It is caused by an ungrounded neutral - a code violation as well as a >safety hazard. While this is a very likely cause, it is not necessarily the only one. Problems "upstream" from your service entrance can also cause voltage fluctuations. SO - if you check your neutral and safety ground connections and find everything both hunky and dory, DON'T just resign yourself to the problem. Call the utility company, and demand that they get their act together. (It may take some convincing - I had an experience with a P.S. co. in Indiana which flatly denied the problem until shown the charts from a recording voltmeter (chart recorder) - but you do have a right to decent electrical service!) Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers%hpfcla@hplabs.hp.com | sentient life-form on this planet.