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Old 10-03-2006, 12:36 PM   #1
Baron
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Question Monitor goes off briefly.........

My PC etc is downstairs, and plugged into the same ring main as my freezer, kitchen appliances etc...
What appears to happen, is that when the thermostat clicks on the freezer, my monitor goes blank for a second and then comes back on again.........darned annoying when I am playing a game

It is a Sony 17" HS73 LCD model.

The rest of the computer is not affected, only the monitor.
I have installed surge protectors from two different wall sockets, so that the load from all the components are taken from two different wall sockets, so the monitor is on a different surge protector from the computer itself.
The other parts like printer etc are evenly spread over the two sockets to even out the load.

Could it be that the monitor is very sensitive to a sudden fluctuation in the power supply ?

Not life threatening, but damned annoying.............any clues ?
Thanks.

Last edited by Baron; 10-03-2006 at 12:39 PM..
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Old 10-03-2006, 04:10 PM   #2
gonzo0815
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Default Re: Monitor goes off briefly.........

Quote:
Originally Posted by Baron
Could it be that the monitor is very sensitive to a sudden fluctuation in the power supply ?

Not life threatening, but damned annoying.............any clues ?
Thanks.
Yes, TFT`s incorporate a SMPS PSu similar your PC does. The difference is, that PC PSU`S are rated for hold-up time, e.g. the time it can deliver the power without proper input voltage. this is somhow about 12 to 30ms. To archive this, in PC PSU`S usually very large inputcapacitors are used. For monitors and other pheriperals there is no standard, wich makes it mandtory to build in a suitable hold-up time. Thus usually there are very small cpazitors build in, to reduce cost.

To improve this, you can either buy a UPS (USV) (recomende, but expensive), buy an inrush current limiter or soft start circuit for your freezer (recomende and not that expenisive) or increase the capazitance in the TFT surply (not neceseralily recomended, as it void's warranty, and can have bad impact if unreflected changes are made).

In the case, your TFT has an external PSU (e.g. 12 to 19v) you can build a circuit containing several thousand uF capacitors (may be something between 4000 to 20000uF provided by 2 to 10 capazitors)at the rated voltage. this can be done wihtout voiding warranty and without to mutch impact to the TFT (in worst case the PSu won`t start due to exzessive capcitanze load).
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Old 10-03-2006, 04:38 PM   #3
Baron
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Default Re: Monitor goes off briefly.........

Thanks for taking the time to reply, and explain things.
I attended a LAN 24hr party some time ago, and I had no problems with the monitor, so it must be the freezer kicking in that upsets the monitors innards.
It has a built in power supply.
I am not clever enough to modify the monitor, and would probably blow myself and/or the monitor up if I were to meddle with it.....
But, getting something like the 'inrush current limiter' or the like sounds like a good solution.
I will have to ask around to find out where I can buy these things.
Thanks
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Old 10-04-2006, 05:28 AM   #4
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Default Re: Monitor goes off briefly.........

That used to happen before i took the computer upstairs. except in this case it is a 19 inch CRT. When the thermostat hits it would go dim and out of focus for a second or so before returning to normal. EVERY electronic device has inrush current. even lightbulbs.
the current is a tiny bit higher than normal but with a high power fridge (or bad one for that matter) you could see literally kilowats of Inrush current. just get a powerpoint loadmeter and see what it does sometimes spikes of over 7 amps hit that fridge.
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Old 10-04-2006, 01:42 PM   #5
Baron
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Default Re: Monitor goes off briefly.........

Thanks for the reply.
My monitor display just goes black for a second and then the display returns, just as if it is switched off and then on again.
I live with it, but it is annoying in games as you can probably imagine
I will look into all the suggestions........thanks again for taking the time to reply.
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Old 10-04-2006, 01:53 PM   #6
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Default Re: Monitor goes off briefly.........

UPS will probably be your best bet. They're not _that_ expensive, and then you're protected from brief power interruptions as well.
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Old 10-06-2006, 03:15 PM   #7
Baron
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Default Re: Monitor goes off briefly.........

Thanks dood, that is something I had thought of, as an all round solution/protection.
From what I can gather, one with about 1000VA and AVR would be good ?
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Old 10-07-2006, 01:41 PM   #8
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Default Re: Monitor goes off briefly.........

I've seen this sort of thing happen many times, with CRTs as well as LCDs. If something on the same mains circuit causes a power surge or fluctuation, the display will be affected. For example, if I'm playing on my old SNES (connected to an old 4:3 TV), and I power-cycle the monitor on my P3 PC, the picture on the TV will jump for a split second.

I had a similar thing happen at work, where I had a dumb PC terminal adjacent to the e-mail/Internet proxy server. Whenever I had to turn the monitor of the server console on, there would be a short glitch (sometimes with a blackout) on the dumb terminal's monitor.

For this reason, many modern CRT monitors have an automatic 'blackout' circuit that triggers whenever the screen mode changes. If it didn't, the screen mode would change and cause a slight fluctuation on the mains power, which could affect other devices. (I've seen this happen with old CRTs)
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