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Computers and equipment resetting

By ozi Eagle ·
Hi All,

I have an issue with a recent installation.


A small supermarket, with 2 new computerised tills running POS software and hardware and 2 old back office computers also running this POS software and one also with accounting software, all networked via a gigabit LAN.

The tills both have a combined scanner / scale and a programmable keyboard. Similar computers, though each has a different model motherboard ( due to needing more PCI slots in one ).

Both the tills ( and the back office computers ) have a UPS - a stand by type, which switches to battery if mains fail. They provide 3 battery backed up and 2 surge suppressed outlets. All POS equipment is run off these UPSs, though not all on battery backup.

Both tills run XP SP2, 500 MB RAM, 3GHz P4, MSI motherboards.


One of the new till computers has now reset its BIOS, to factory default, twice in a few weeks. The problem here is that the default turns off the LAN and USB ports, rendering the machine virtually useless. ( I have not tried replacing the CMOS battery, as the computer is brand new, and because of other problems elsewhere, see below )

On the other till, the computer is behaving OK, but the scanner / scale has frozen, the programmable keyboard started producing multiple zeros, when the zero button was hit.
Unplugging both devices and re connecting ( i.e. forcing a reset ) fixed the problem, temporarily.
The scanner / scale at this second till then become very erratic, looking as if it was resetting itself every so often. Swapping the two scanner / scales seems to have fixed this. ( They were swapped because the original till with the problem is the one that is used the most, and I suspected a faulty unit, its working OK in the other location.)

The older back office computers have not had any bad symptoms reported, but then they don't get used as much.

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by ozi Eagle In reply to Computers and equipment r ...


I suspect a mains interference problem, as the shop has one wall of refrigerators, a half tonne of air-conditioning and a railway line (electric) a block away.

I have fitted clip on ferrite suppressors to all the UPS power leads, but this does not seem to have helped. I am looking for other ideas and a possible supplier of inexpensive line conditioning or low frequency filtering equipment, standard surge suppressors with EMI / RFI filtering only filter from about 100kHz and up. I suspect low frequency switching transients. So far the only items I have been able to locate are in the thousand dollar plus price range, and this is a bit too much to trial, especially if it doesn't work.

The UPS log does not show any untoward power problems, but then if it is a transient problem the UPS may not be "triggered" by the transient.

It may also be an earth loop problem.

All suggestions welcome.

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by TheChas In reply to Computers and equipment r ...

One problem, is I don't know what equipment brands are available to you.

Here in the US, I would start with Sola or Topaz for line conditioners.

You might try a less expensive line isolation transformer rather than a full line conditioner.

If the transformer helps noticeably, then you can evaluate the value of a full line conditioner.

Another option, would be to build up a line filter. Corcom used to make filters that went down to the 10 KHz range. I built one into a box with outlets on it and have used it many a time to prove a line noise problem.

Do the network cables run close to any mains?
For that matter, are they as far away from light fixtures as possible?

A noisy ballast transformer can throw off a lot of RF noise.

Yes, I would go ahead and put in a new CMOS battery on the one system.

Another thing I suggest you do, is stand back and observe the operation for a period of time.

I had one PC system that was "acting" up for months on end with no solution in sight.
Turns out the user would set things on top of the keyboard, and the custom software locked up when the keyboard buffer got full. Until I observed the process for a half hour, there was no clue as to the source of the problem.

How environmentally sealed are the scale / scanner and keyboard?

Could the clerks be cleaning things in a manner that gets cleaner inside things, or dripping down the cables?

Are the PCs up off the floor and protected from floor cleaning?

On the power side, you might want to canvas the local electricians and see if any of them has a good power line monitor. Many can record spikes, dips and transients. Renting one for a week would help prove the need for a line conditioner.

Since it has been in the PC news, don't forget to inspect the filter caps on the new motherboards. Look for bulges or leakage on all of them.

When all else fails, drop back and look over the situation from another perspective.

Good luck,


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by ozi Eagle In reply to

Hi Chas

Thanks for your reply.
I'll see if I can put a couple of low pass filters together.
The running of network cables is unknown, done by licensed installer.
The keyboard is spill proof and the scales are built to be self draining. The computers are in an open cabinet in the counter ( no heat problem ).
I will try a new CMOS battery next time I'm there.
Filter caps could be a problem if only the computer(s) were being affected, but unlikely since the scales are also being affected.

I'll post more comments as I work my way through.

Unfortunately I have to rate this answer to be able to submit my comments. I don't reject it, but haven't been able to try any ideas yet.

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by CG IT In reply to Computers and equipment r ...

what's the POS software being used? Is it SAMS 4? often times SAMS 4 POS works great with Windows 98 but stinks with XP. Even with their updates. One thing to check is the polling between registers. XP SP2 is great but SP2 can break stuff like POS software where Windows runs in the background. The BIOS reset thing, follow The Chas's advice. He's the guru of hardware.

If this is IBM POS then I would say the problem might be with the POS server. If you have internet access anywhere on any of the computers [presumably all are networked together, I'd say maybe infection is the culprit.

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by ozi Eagle In reply to


Thanks for your thoughts.
The software is an Australian product called Retail Manager. The problem is unlikely to be related to this software as the scales are being affected as well.

Unfortunately I have to rate this answer to be able to submit my comments. I don't reject it, but haven't been able to try any ideas yet.

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by mjd420nova In reply to Computers and equipment r ...

Check your local phone book and find an instrument rental. A line monitor can be as low as about$30. a week. This will enlighten you
and might even scare you, so I'd say that a broadband filter would give the best coverage.

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by ozi Eagle In reply to

Poster rated this answer.

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by Toivo Talikka In reply to Computers and equipment r ...

Are there any environmental hazards around? I had once a client whose office was next to a police station and one of the PCs was somehow in the line of the transmission beam from some sort of a radio transmitter. Once the PC was moved a couple of meters, the obscure problems sorted themselves out and disappeared...

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by ozi Eagle In reply to

Replacing the network cable, via a different route, solved the problems

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by electricdragon In reply to Computers and equipment r ...

The suggestions I had have already been covered, so I have nothing to add that might help your computer problem, but I thought I might lend you a little board help. :-) (Just to keep in mind in case you have anymore problems in the future.) I see that you did not wish to reject a couple of the answers you received.
You can add more than one comment to your original post, rather than commenting on a reply itself, simply add your comment to your own post and indicate who (which helper) you are replying to, that way you can keep a running commentary with those that are trying to lend a hand and avoid rejecting their answers until the problem is solved, or not solved.
Of course that doesn't apply to the few silly people here that give answers like "Eat some chicken soup first, then start your computer.." LOL

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