Cable Modem and the AC

joevennix · Post by **joevennix** » Sat Jun 02, 2007 6:33 pm

Alright, this is getting so frustrating. Here's the problem: Everytime my AC comes on, from around 8 AM to 6 PM (it comes on randomly with the thermostat between those times), my cable modem craps out. The power is still on, but the internet stops working.

Of course my first thought was, stupid Time Warner electricians, they laid the cable over the AC vent, and it's causing interference. A quick look in the attic shows no such thing, hell I even had a guy come down and check the conductivity of the line with the AC on and then again with it off. No difference.

I'm 100% sure it's the modem and not the wifi router, since even when I directly connect my laptop to the modem, it still doesn't work.

It's a recurring problem now, every few months it will begin happening. I've been thinking about it for a long time, and still've got nothing. Basically the cable company's stance is: Go trade in your modem for a new one (their modems are basically crap). In a few months they break. Now they're giving out a new model, and these don't even work (with the AC on) in the first place.

Any ideas?

tom61 · Post by **tom61** » Sat Jun 02, 2007 9:40 pm

I encountered same thing, but with a router. Other than trying a UPS I can't give you much advice. I ended up replacing the router. Linksys makes cable modems, so I'd give them a shot.

Most likely the power drain when the AC starts up causes just enough of a brown-out that the modem can't get enough power.

Post by **Triton** » Sat Jun 02, 2007 10:23 pm

either that or some sort of interference. try moving the modem to a different outlet or something maybe?

vskid · Post by **vskid** » Sat Jun 02, 2007 10:26 pm

tom61 wrote:Most likely the power drain when the AC starts up causes just enough of a brown-out that the modem can't get enough power.

Would his house really be that maxed out on power usage that it wouldn't let it get enough power? You could try powering the modem with batteries.

I think Triton might be right with the outlet interference.

joevennix · Post by **joevennix** » Sat Jun 02, 2007 11:01 pm

tom61 wrote:Most likely the power drain when the AC starts up causes just enough of a brown-out that the modem can't get enough power.

That's pretty much what the cable guy told me, right before referring me to the warehouse to swap modems. I'm going to Fry's tomorrow, so I might pick up a new modem there.
Triton - I've tried changing it to a different outlet (especially since it's on the 2nd of a chain of 3 surge protectors), no luck. I think there's just too much current draw.

tom61 · Post by **tom61** » Sat Jun 02, 2007 11:05 pm

vskid wrote: Would his house really be that maxed out on power usage that it wouldn't let it get enough power?

Depends on his house, my house was wired in the 1930's most likely, and was never designed to handle AC. The lights dim briefly every time an appliance comes on.

Post by **bicostp** » Sun Jun 03, 2007 7:58 am

joevennix wrote:
tom61 wrote:Most likely the power drain when the AC starts up causes just enough of a brown-out that the modem can't get enough power.
That's pretty much what the cable guy told me, right before referring me to the warehouse to swap modems. I'm going to Fry's tomorrow, so I might pick up a new modem there.
Triton - I've tried changing it to a different outlet (especially since it's on the 2nd of a chain of 3 surge protectors), no luck. I think there's just too much current draw.

A new modem probably won't fix it. Put the modem on an extension cord and plug it in in another room. That might fix it. (It needs to be on a separate circuit.)

We have a similar problem: whenever our window AC comes on the TV mutes for a couple seconds.

vskid · Post by **vskid** » Sun Jun 03, 2007 9:24 am

You guys do know you can add more circuit breakers, I think thats what the people did that installed our AC. Our lights dim for a second when the air compressor comes on, but I think thats just in the family room, which I think is on the same breaker as the garage.

Kenny_McCormic · Post by **Kenny_McCormic** » Sun Jun 03, 2007 9:40 am

methinks the voltage drop from the extreme start up load an ac has makes the router reboot maybe put a big cap in the router so the voltage drop isnt so sudden?

timmeh87 · Post by **timmeh87** » Sun Jun 03, 2007 7:45 pm

indeed, your house wiring dosent even have to be old for you to experience brownouts when large motors come online.

my lights always dim for a second when the fridge comes on, but my computers are usually ok. my house was made in the 80s.

usually houses come with two separate 120v AC lines, 180 degrees out of phase. this is so that you can get 240v across both of them for running large appliances. the standard configuration is that there is one power rail per side of your breaker box with the neutral rail going down the middle.

if you AC is 120v, you could (carefully with adult help or whatever) pop open the breaker box, figure out which side your AC is on, and try putting your electronics on the other side. it seems to me that this might help, but i cant actually verify that.

you could also buy a proper power regulation unit if it comes to that, there are wide range of products to choose from. they usually have a processor inside and some way to actively smooth out your power. maybe giant capacitors or whatever. who knows. they usually advertise nanosecond response times.

also, about what kenny said: the cap would have to be inside the modem obviously, after the power has been stepped down and rectified. dont hook caps up to mains AC. it may help though. something in the high uF range, a few hundred maybe. if its too big the response time becomes too slow to help. you can pair a big one and a small one for immediate response and long lasting effect.

HotDog-Cart · Post by **HotDog-Cart** » Sun Jun 03, 2007 8:26 pm

I get the same problem when my brother uses the microwave. My internet cuts out, when he uses it. Its because my frequency channel on the router shares the same channel with the Microwave. Easy to fix, I'm just lazy.

joevennix · Post by **joevennix** » Sat Jun 09, 2007 6:21 pm

I tried adding two electrolytic capacitors along the power cord, after the AC-DC conversion. One was 220uf - 24V, and the other was 2.2uF - 50V. The power supply says 12VDC along the side, but my multimeter shows 17, it might be wrong though. Anyways, I did all that and plugged it back in. Turned it on while the AC was running and of course it still didn't work. So I turned off the AC, let the caps charge for a second, then turned it back on. I was surprised to find it worked great!... for 2-3 minutes. Then I guess the capacitor discharged again, and it stopped working.

I'm thinking about buying a UPS, this one caught my eye. I'll give it a try and if it doesn't help, I'll return it. What do you think?

Post by **bicostp** » Sat Jun 09, 2007 6:41 pm

It should work. A bigger version helped our TV. (It's one of the big white ones that can run a desktop PC for 15 minutes. Yay work throwaways!)

joevennix · Post by **joevennix** » Sat Jun 09, 2007 8:31 pm

Okay, the capacitor solution actually did work. I guess I just didn't give it enough time to charge or something. Anyways when I got home from dinner later tonight the AC was on, and the internet worked great. So, disaster averted, I spent $0 on the fix, just the way I like it. And finally I can actually stay online during the day, and get my money's worth from RoadRunner.

Thanks everyone who helped, I'm so glad this problem is finally gone.

900th post ftw

-Joe