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Warning, don't fry your modem.

Warning, don't fry your modem.

  Some years ago, an EMT vehicle backed over and destroyed my Hughes dish. The next morning I called my trusty tech company, and the first thing he asked me was if the coax was damaged, and next if had I cut the power to the modem.

 

  I didn't discover that the coax was broken until the next morning, and I hadn't powered down the modem for all of that time. He said that with all the rain we had that night, that the modem was probably fried, so he would make sure that the tech he sent brought a new modem with him, and for me to unplug the modem at once, even though it was probably too late by now.

 

  He was right, the modem was fried.

 

  I knew that coax was designed to carry extremely weak signals, and I didn't think there was enough power available to cause any damage. Looking back now, I think it was probably the transmit signal to the dish that probably had enough power to do the damage, and the water on the broken end of the coax caused a short on the transmit circuit of the modem. At least, that's my theory.

 

  I suspect that this may be true for the newer generation modems also. I'm going to play it safe from now on, and if anything ever happens to my dish again, I'm going to immediately cut the power to the modem.


PREJUDICE, n. A vagrant opinion without visible means of support.
The Devil's Dictionary

1 ACCEPTED SOLUTION

Accepted Solutions
Assistant Professor

Re: Warning, don't fry your modem.

Yes, there is DC power supplied by the modem going through the coax to power the radio on the dish. Under certain situations the modem can be damaged if the power is shorted out. There are protections built in but they don't always work.

 

Also one reason we say to power down the modem from the wall receptacle, not the plug on the back of the modem.

27 REPLIES 27
Assistant Professor

Re: Warning, don't fry your modem.

Yes, there is DC power supplied by the modem going through the coax to power the radio on the dish. Under certain situations the modem can be damaged if the power is shorted out. There are protections built in but they don't always work.

 

Also one reason we say to power down the modem from the wall receptacle, not the plug on the back of the modem.

Re: Warning, don't fry your modem.


@BirdDog wrote:

Yes, there is DC power supplied by the modem going through the coax to power the radio on the dish. Under certain situations the modem can be damaged if the power is shorted out. There are protections built in but they don't always work.

  Given the behavior of my tech guy I would guess that they seldom work, because he was absolutely sure that I was going to need a new modem.

 

  There's obviously a lot more happening on that one piece of coax than I ever thought there would be.   BTW I hate coax.  The first computer network I worked with,  was coax run overhead on already existing poles.  It was an absolute nightmare to keep working.   After we had done about everything that we could think of to try to fix it.  I told my supervisor the only thing we could to do now was to change all the poles.  Smiley Embarassed)> 

Sophomore

Re: Warning, don't fry your modem.

lets be honest...your modem is supplied power by an AC/DC converter. A cheap one at that. If the modem failed before the converter did...HughesNet needs a new modem manufacturer. Plain, simple, to the point.

Distinguished Professor IV

Re: Warning, don't fry your modem.

@gaines_wright 

 

I remember a post from a year or two ago in which someone's modem was fried due to corrosion in/on one of the connectors and water getting inside the cable and shorting the system out.  If I remember correctly it was on an older legacy installation.  I think they may have had to replace the radio, as well, though I may be conflating that with something else.  It was most likely from an insufficient amount of dielectric grease being applied to the connector or the installation tech just forgetting to do so.  Zap!  


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Sophomore

Re: Warning, don't fry your modem.


@GabeU wrote:

@gaines_wright 

 

  It was most likely from an insufficient amount of dielectric grease being applied to the connector or the installation tech just forgetting to do so.  Zap!  

 

Just a tidbit of information, while typical coax connectors are not IP rated, the application of an additional dielectric will change impedence and negatively impact throughput, as the cable, connectors, transceiver, and receiver are all designed to be impedence-matched. Just an interesting thought to consider. Which is more important? Ingress protection, or maintaining transmit power and throughput without any significant loss or gain (depending on how you look at it)


 

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Sophomore

Re: Warning, don't fry your modem.


@gaines_wright wrote:

  Given the behavior of my tech guy I would guess that they seldom work, because he was absolutely sure that I was going to need a new modem.

People often say that about me when I suggest they buy new stuff...oh...erm...I will just be over here looking at my tractor pics....

                                                                                                                                                 MrB.png

 

Distinguished Professor IV

Re: Warning, don't fry your modem.


@vladams2015 wrote:

Just a tidbit of information, while typical coax connectors are not IP rated, the application of an additional dielectric will change impedence and negatively impact throughput, as the cable, connectors, transceiver, and receiver are all designed to be impedence-matched. Just an interesting thought to consider. Which is more important? Ingress protection, or maintaining transmit power and throughput without any significant loss or gain (depending on how you look at it)


The connector in question was likely not weather sealed properly, as well.


AMD FX-6100 | Samsung 250GB 840 EVO SSD | Western Digital Blue 500GB HDD | 16GB DDR3-1866 | EVGA Geforce GTX 550ti | Windows 10 Pro 64-bit
Sophomore

Re: Warning, don't fry your modem.

obviously so, however the point is that a type F connector (while not IP rated per se) are standard IP64 and applying a dielectric is poor practice...but one is left to consider: do we care more about a cable being submersible, or about ensuring an impedence match. 

Distinguished Professor IV

Re: Warning, don't fry your modem.

I have no idea, but what I, HughesNet, and the installers care about is a proper installation, which requires the proper application of dielectric grease and weathersealing of all outdoor connectors.  


AMD FX-6100 | Samsung 250GB 840 EVO SSD | Western Digital Blue 500GB HDD | 16GB DDR3-1866 | EVGA Geforce GTX 550ti | Windows 10 Pro 64-bit