Power supply unit faulty? or something else?

Addiscomber

I bought an Acer Aspire T180 PC last November. From time to time when I switch off the power at the wall socket, after shutting down the computer, the main trip on our consumer board has activated. As you can imagine this is causing great annoyance to the whole family.

We tried different power cables and a different surge protector, and came to believe that the wall socket was the problem. We rearranged the room so that I used a different wall socket, and all has been well for about 3 months, until last night when it happened again. The computer had been shut down for over an hour before the wall socket was switched off, but I believe that computers still draw some power if they are connected to the ring main, which is why we disconnect them at bedtime.

As the PC is less than 12 months old I am going to get in touch with the supplier about it, but would be grateful for any thoughts as to what could be causing this, as I like to sound as though I know what I am talking about.

squeaky

Try plugging some other item into that first "dodgy" socket and see if turning it on and off trips your breakers. Have the computer completely unplugged while doing this.

It does tend to sound as though you have a problem with either your sockets and their wiring, or your unit.

At least a test with something other than your computer will let you know if it is only the computer causing this, or if anything in those sockets does it.

Stephen_Leak

From the above, I still suspect your domestic wiring, possibly with the earthing.

If you have or can borrow one, plug one of those portable circuit breaker sockets into a socket on each circuit. If it trips, you have a problem.

The reason I specify using a portable circuit breaker is that they are relatively easily available, and can actually detect an earth to neutral reversal, the one thing a professional Martindale electrical tester can't detect.

epninety

Did you try removing the surge protector?

Addiscomber

Thanks.

Squeaky,
We did try different items in the wall socket that I was using originally, but nothing else seemed to cause a problem, but then with the computer it is intermittent, which of course makes something very hard to diagnose. My husband also opened up the socket to see if he could see anything obvious that was wrong, such as a loose wire, but our knowledge doesn't go beyond that, and we know not to go beyond our limitations.

Stephen,
We do have a portable circuit breaker for use with the lawn mower. Should I be trying it with something simple like a table lamp plugged into it, or by itself?


If we have a problem with our domestic wiring why would it only show up when one particular item is used?

Addiscomber

epninety

Sorry, you must have posted whilst I was composing my reply.

I have not tried using the computer without a surge protector as I thought that one should always use one with computers. We do have several, so have tried different ones. Please could you explain why you think I should try without one?

Markee

Text deleted due to double posting

Markee

The first thing you need to do is remove the surge protector from the equation - just to eliminate it, as suggested by epninety.

I realise you have already tried plugging in another one, but knowing the way some surge protectors work and the way RCDs (trip) work, they don't always live well together!

In addition to other suggestions, can you try turning the PC socket off with JUST the pc plugged in?

Most houses have their ring circuits split between upstairs and downstairs. So if your PC is upstairs, unplug everything upstairs except the PC. If you need to check this, just switch off the circuit breaker MCB (not the trip, the individual circuit MCB) and have a look around the house for anything that is dead that was working before. If you find anything dead, unplug it before turning the MCB back on. You should now have nothing else but your PC plugged into that ring circuit.

Also, you say you turn the socket off at the wall and the PC is plugged into a surge protector. Presumably there are other things also plugged into the surge protector such as monitor, printer, speakers etc? Assuming the surge protector is a multisocket type unit, maybe it's something else that is casuing the problem, so to elimate them, just plug the PC into the wall socket.

Good luck, and please come back with your findings.

Markee

The reason you need to remove the surge protector is that the way they work can sometimes trip off RCD trips.

If there is a surge in the mains, the surge protector (depending on type) will filter off the extra through to your earth wire safely without damaging your equipment.

The way an RCD or ELCB (your trip) works is by sensing inbalances in your phase/neutral conductors. It's a bit complicated, but basically the trip picks up on current flowing to earth.

See the pattern here?

Surge protectors work by trapping surges and sending them safely to earth.

RCD trips work by sensing unusual current flows to earth.

It may not be the surge protector, but we need to eliminate it.

Addiscomber

OK. Lots of things to try. I shall have to wait until my husband is here to help as I am disabled. It also sounds as though it would be best when our sons are out, so he might need to take a day off work.

What is bothering me is that it happens infrequently enough to be hard to pinpoint, but often enough that it needs sorting. At least we do know that it is definitely to do with my computer set up, and we are not faced with having to work out which appliance is doing it.

I shall certainly come back with our findings eventually, as there is nothing more infuriating than searching for a topic and finding an inconclusive thread.

Markee

Good luck - and if you need any help with the suggestions we have made, please don't hesitate to ask!