pc freezes

[jtd.75]

Can anyone help, over the christmas I was down in Cardiff at my daughters, and she had a problem with her pc (HP Pavillion 730UK) it froze when she tried to use the mouse, so she bought a new one thinking that was the problem but no. I brought it home for a friend to have a look and he put it down to all the gobbledygook she had on it and done a factory restore on, I had it with me for 10 days and it was working fine so I took it back down to Cardiff and when we set it up it froze again when we tried to use the mouse. She had a word with the IT maintenance man at the hospital where she works who thought it might be the graffics card and this he changed he kept it and all the bits and pieces for over a week and all was ok. she brought them home again and it froze again. she has tried setting it up in every room in the house and has the same problem. She tried it in the house next door and its ok there. Has any one got any ideas as to what might be causing the problem. I have asked her to get SWALEC into check out the electrics. Her house is about 28 yrs old. This one might be for you Alex.
Jimmy

[JimK]

Might be the power supply. A very small dip in the supply might be enough to trip the machine up without taking it down.

Might be worth getting a UPS (un-interruptible power supply). That will get over any dips, but will also help by giving a nice stable supply to the computer even while the house supply is on.
They range from fairly cheap units that with run the computer for a couple of minutes (enough to shut down), to units that can run a home office for a few hours.

[chickenjohn]

I would advise getting an Apple Mac, as according to my recent experience these are the only computers tat can fix themselves!

[alex_holden]

It sounds like something in the house might be putting out electromagnetic interference that's affecting it. Try to identify a pattern to when it happens. Does it perhaps do it when the boiler sparks up, or when somebody switches a fluorescent light on elsewhere in the house? Do the lights flicker just before it freezes?

[JimK]

Alex, what about if the case isn't grounded? A grounded case should act like a Faraday cage and protect the PC from EM noise, but if the house has earthing troubles then maybe the PC case isn't shielding because it's not earthed properly?

[jtd.75]

We have tried to eliminate various possibilities and all to no avail, one thing that I forgot to mention was that her laptop does not suffer with the same problem although it is a few years older than her desktop. I tried checking for loose neutrals in the power, from the meter to the consumer unit and all the connections in the sockets and all ok. I have even disconnected the sky cables from the th and the bt line as I know that can cause problems with the telephone line. (thats from experience when I was a bt engineer). She has only started to get this problem since she moved into the house in May. there is no mains earth leakage either.

[alex_holden]

Alex, what about if the case isn't grounded? A grounded case should act like a Faraday cage and protect the PC from EM noise, but if the house has earthing troubles then maybe the PC case isn't shielding because it's not earthed properly?

It's a possibility, though consumer grade PCs tend not to be very well shielded in my limited experience (I used to be a radio amateur). Any apertures in the case will leak RF in and out.

[JimK]

Hmmm. The mere fact of having a battery means that laptops are basically immune to power supply problems.

Looks like you've done a lot of supply checks already, but can I ask how you did them? These problems can be down to transigent events on the supply that don't show up very well on meters that average many readings, like a normal multimeter. Sometimes you need to watch what happens on the supply in real-time, using something like an oscilloscope.

I second your plan to get the power company to go over the household wiring, and they should also check the quality of the incoming supply. We recently had problems caused by failure of the insulation/casing on an underground cable - thankfully not on our land so we didn't have to pay...

[jtd.75]

Hi JK only meter that I was using was a digital one, I hear what you are saying about a os/scope and I also know power can play havoc with modern day electronics. I spent over 35 years on faults but then you could fault down to a component where as now a chip will control many things. Yes never thought about the battery in the laptop like you say the power from the socket to the laptop is backed up by the battery

[jtd.75]

for those that are interested the follow up to my daughters pc that kept freezing was all due to a faulty nuetral in the house under the floor boards. The Gas man was there for over 6 hours yes thats right the gas man (she has a contract 400 care plumbing and electrics with them). The house is only 18 years old and it only has 1 ring main for all the sockets and 2 ring mains for the lights (1 for upstairs & 1 for down stairs). He said that he had not come across that before!!!. Under the floor boards the was junction box's galore I was taking up floor boards for him while he was chasing the dodgy neutral and in the end it was in the airing cupboard under the floor boards. All is now ok and he recommends that we sort out the ring main situation and if she is planning on staying in the house for any lenght of time that she might consider having the consumer unit up graded she has not been living in the house 12 months yet. I supose the lesson here is she should have had a full survey done before she bought it.