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-   -   Cable modem plugged into UPS unit problem (http://www.ehmac.ca/showthread.php?t=60218)

GratuitousApplesauce Jan 14th, 2008 09:04 PM

Cable modem plugged into UPS unit problem
 
Santa gave me a UPS for Xmas, which is great because this time of the year the power usually goes out here in the Gulf Islands a couple of times a month minimum. I've been on my Mac when the power goes off - on - off - on - then finally off and it ain't purty to watch. So far no damage but it feels so much better having this battery between me and the flaky power lines.

Last night I noticed my internet connection going off and on frequently. This is also not unusual here since the cable infrastructure is quite primitive. I assumed they were having some system problems but when it continued this morning I phoned Shaw cable.

It turns out they weren't having problems, but the tech could see that my connection was going out a lot. As an aside I mentioned that I had been using a UPS for the last couple of weeks and he suggested that I try plugging the cable modem directly into the wall instead of the UPS. This didn't make sense to me because I didn't see how it could make a difference, - but it did.

Since I've had the modem plugged into the wall the modem has shown solid green lights. I looked around Google for someone else experiencing this but didn't find anything. Has anyone else seen this? Does anyone have a theory on why this might be happening?

Although I haven't seen any problem with my G5 PowerMac and 2 monitors plugged into the UPS I'm now wondering if there's some reason to be concerned.

Eric0 Jan 14th, 2008 09:10 PM

Strange that your having that problem with your modem. I've never tried plugging the cable modem into my backup system, but was thinking about it the other day when the power went out.

I wouldn't worry too much about your G5. I've had a backup system for 5 years and all my PC's and peripherals are still working.

nowlive Jan 14th, 2008 09:12 PM

Quote:

Originally Posted by GratuitousApplesauce (Post 624442)
Santa gave me a UPS for Xmas, which is great because this time of the year the power usually goes out here in the Gulf Islands a couple of times a month minimum. I've been on my Mac when the power goes off - on - off - on - then finally off and it ain't purty to watch. So far no damage but it feels so much better having this battery between me and the flaky power lines.

Last night I noticed my internet connection going off and on frequently. This is also not unusual here since the cable infrastructure is quite primitive. I assumed they were having some system problems but when it continued this morning I phoned Shaw cable.

It turns out they weren't having problems, but the tech could see that my connection was going out a lot. As an aside I mentioned that I had been using a UPS for the last couple of weeks and he suggested that I try plugging the cable modem directly into the wall instead of the UPS. This didn't make sense to me because I didn't see how it could make a difference, - but it did.

Since I've had the modem plugged into the wall the modem has shown solid green lights. I looked around Google for someone else experiencing this but didn't find anything. Has anyone else seen this? Does anyone have a theory on why this might be happening?

Although I haven't seen any problem with my G5 PowerMac and 2 monitors plugged into the UPS I'm now wondering if there's some reason to be concerned.

Hi!! For me to best answer your question I need to know the manufacturer of your UPS and we can start from there :)

BReligion Jan 14th, 2008 10:14 PM

Quote:

Originally Posted by GratuitousApplesauce (Post 624442)
Although I haven't seen any problem with my G5 PowerMac and 2 monitors plugged into the UPS I'm now wondering if there's some reason to be concerned.

I would check the load on your UPS... Monitors (CRT Monitors at least) are a huge drain, and you might *might* be overloading it. Why that would effect just the Cable Modem and not the G5, i don't have an answer for you.

I have my modem, router, and server box all into the battery on one of my UPS's, but my monitors are in the surge section of the UPS, not covered by battery.


BReligion

Eric0 Jan 14th, 2008 10:17 PM

Quote:

Originally Posted by BReligion (Post 624479)
I have my modem, router, and server box all into the battery on one of my UPS's, but my monitors are in the surge section of the UPS, not covered by battery.


BReligion

Just curious how you shut down your systems in the event of power failure with no monitors?

BReligion Jan 14th, 2008 10:24 PM

Quote:

Originally Posted by Eric0 (Post 624482)
Just curious how you shut down your systems in the event of power failure with no monitors?

I have UPS software installed on the server, and critical services start to shut themselves down after 6 minutes of running on battery, at that point if i am home i go downstairs and move the core monitor into the battery section of the ups, giving me enough time to shut it down....

I think the last time i checked i got about 15-20 minutes with no monitor, about 6-8 with 17" crt on and running

BReligion

8127972 Jan 14th, 2008 10:36 PM

Someone else here said that you should check the load on the UPS. There's a calculator on the APC site that can help you with that:

UPS Selector Sizing Applications

Basically their model numbers correspond how many VA's of runtime the UPS has. So if their number matches the VA's on your UPS, you're likely not overloading the UPS (and therefore perhaps there's another reason why you're having the symptoms that you describe, like a defective UPS).

GratuitousApplesauce Jan 14th, 2008 11:08 PM

Quote:

Originally Posted by nowlive (Post 624444)
Hi!! For me to best answer your question I need to know the manufacturer of your UPS and we can start from there :)

http://images.bestbuy.com:80/BestBuy...8129544_rb.jpg

It's an APC Back-UPS XS 1300VA LCD. Supposed to be able to handle 780 watts.

Hmmm, I may be starting to answer my own question. I'm reading on some forum that a G5 2Ghz DP PowerMac might be using 400 watts if running full blast, but I also have a second HDD and a bigger video card than the stock model. Contrary to what I mentioned above, I don't have the 2nd monitor plugged into the UPS section, just the surge section. The main LCD probably pulls 100 watts. I guess if the power draw is peaking it might have been knocking the modem out. I'll wait for more knowledgeable folks to answer that.

I don't really need the modem plugged into the UPS, because when the power goes out the internet here doesn't work anyway.

nowlive Jan 14th, 2008 11:45 PM

Quote:

Originally Posted by GratuitousApplesauce (Post 624503)
http://images.bestbuy.com:80/BestBuy...8129544_rb.jpg

It's an APC Back-UPS XS 1300VA LCD. Supposed to be able to handle 780 watts.
.

Ok perfect thank you for providing me with that information. There are really only two possible scenarios that come to mind that would logically make sense with regards to your issue. Lets begin with the first one.

1) Assuming that you are taking full advantage of the UPS services such as data-line protection, what may be occurring is the UPS is inflicting disturbances into your cable data line. How does this occur you may ask? Well Some companies for example, have a nasty habit of utilizing Metal Oxide Varistors which have a relatively high capacitance. It would make more sense to use sidactors because they not only have remarkably low capacitance, but its surge suppression capabilities are superior.

2) That APC model produces a Pulse Width Modulated Sinewave. Power disturbances that exceed a predetermined tolerance threshold will cause the relay in the UPS to close and the inverter will immediately (within 2-6ns) begin to supply emergency backup services. When this occurs a Pulse Width Modulated Sinewave is produced. Some electronic equipment is capable of handling this "dirty" power because of the filter networks in their power supplies. If you notice that your internet gateway is exhibiting irregularities check to see if your UPS is running on battery at that moment. If it is then your gateway may not be compatible with the sinewave produced by the UPS.

If you have any questions please don't hesitate to let me know!!

KPenner Jan 15th, 2008 12:17 AM

What is quality of your power on Salt Spring? I ask because I once experienced a problem with a UPS running on a small hydro system (3 Valley Gap). The UPS kept cutting in and out and when I took it off the small hydro grid and ran it on a BC Hydro grid, it worked fine. When it was returned to the small hydro grid the thing blew up, an I mean blew up. A second UPS installed in same location acted the same way but we never tested the blow up theory again. I'm not saying this is your problem as you seem to have only one device acting up, not the UPS itself.


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