# Spark coming from Coax



## blahblahblah65 (May 23, 2008)

Everything with the following setup was working flawlessly until about 2 weeks ago. Internet started going up and down all the time and continues. Comcast tech came out and said everything is fine and then he disconnected the Dish coax coming FROM the VIP722, when he disconnected it, and saw it spark against the diplexer while moving around. He said that's "bad" and could be causing the problem.

Setup is as follows:
1) Comcast & Dish outside coax *--->* 
2) Diplexer (Dish on the Power Pass side) at home entry point *---->* 
3) Coax cabling through the home's walls to a main panel in the laundry room (there is typically a splitter here to distribute coax signal to each room but I have removed it and uses a female-female connector to just have coax in one room) *---->* 
4) Diplexer at room entry point, again power side to dish, non-power side to Cable Internet modem.

Is this spark bad? I thought the whole point of the diplexer is that it passes DC on only one side so it shouldn't be getting back into the Comcast modem? Does Dish normally pass voltage over their coax?

Any thoughts on how to fix/if this is a problem would be appreciated.
thanks


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## P Smith (Jul 25, 2002)

it is bad

get an electrician or buy special H-N-G tester (big plug with three indicators)
test all outlets
be sure ground is OK on each plug


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## blahblahblah65 (May 23, 2008)

P Smith said:


> it is bad
> 
> get an electrician or buy special H-N-G tester (big plug with three indicators)
> test all outlets
> be sure ground is OK on each plug


Thanks. In general, though, is my setup okay in terms of the diplexers to run Comcast internet and Dish over the same line inside the wall? I believe I found that suggestion on this site, but it has been a while...


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## P Smith (Jul 25, 2002)

man
inside the wall you have two phases, one neutral and one ground wires..
get the electrician !


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## blahblahblah65 (May 23, 2008)

P Smith said:


> man
> inside the wall you have two phases, one neutral and one ground wires..
> get the electrician !


Sorry if I was not clear....in a hypothetical perfectly wired home, is the setup I have running with the diplexers okay to do?

I plan on getting the electrician. I am asking, once this electrician fixes whatever this problem is, is it okay to then use the diplexers?

edit - this post says a spark will always be there?? http://www.dbstalk.com/showthread.php?t=21394

edit again --- to clarify...spark is coming *from *the VIP722 BEFORE i plug it into the diplexer


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## P Smith (Jul 25, 2002)

well, connecting sat cox while a receiver is plugged is big NO NO [doodoo]

and yes, it could be the reason, but I assumed you do follow the rules: no mangle with coax while your receiver is powered


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## VDP07 (Feb 22, 2006)

While diplexing your Sat signal and your cable internet signal on 1 cable is not an officially supported method, it is a common method used by many and generally works without issues. It's also common for Cable techs to disconnect any connected satellite hardware or cabling from "Their" cabling. 
Your Satellite receiver sends DC voltage up to the Sat LNB via the coax and the spark you described is a result of the tech shorting the connection when he removed the cable. Very common and normal occurrence when doing so with the receiver powered up.


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## AZ. (Mar 27, 2011)

hard to follow your post...Is your dish grounded? Dishes lnb's do take power so if the recievers are on there sending voltage to the dishes lnb....

with all dish network recivers unpluged do you still have the arking on the coax?


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## Wire Nut (Apr 6, 2012)

There is an 18VDC potential between the center conductor and the shield of a satellite line when the receiver is plugged in. As VDP07 suggested, I believe the Comcast tech shorted out your receiver. If the problem was electrical in nature, he would have been shocked or even electrocuted when disconnecting the coax. 
As for your internet, the short answer is you need a separate coax. I have tried the diplexers in the past, they burn out in 4-6 months every time. If at all possible, run another line or physically relocate your cable modem to another coax jack in the house and use wireless.


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## blahblahblah65 (May 23, 2008)

AZ. said:


> hard to follow your post...Is your dish grounded? Dishes lnb's do take power so if the recievers are on there sending voltage to the dishes lnb....
> 
> with all dish network recivers unpluged do you still have the arking on the coax?


No arcing on the coax when the 722 is unplugged from the wall. Electric company came out today and said 4volts are coming from the coax from the 722 while it's plugged in. He checked their company's grounds and the 3 sockets we're using inside and said all were ground properly.

Any ideas?


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## P Smith (Jul 25, 2002)

That's is too low for DC and too high for AC of normal working 722
it must be 14 VDC/18VDC(legacy) or 19 VDC(DP/DPP) and 0 VAC

did he measure voltage between all boxes(metal part) when no coaxes connected - only power cords ? 722 and cable box and AV and TV etc

was that voltage AC or DC ?


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## blahblahblah65 (May 23, 2008)

P Smith said:


> That's is too low for DC and too high for AC of normal working 722
> it must be 14 VDC/18VDC(legacy) or 19 VDC(DP/DPP) and 0 VAC
> 
> did he measure voltage between all boxes(metal part) when no coaxes connected - only power cords ? 722 and cable box and AV and TV etc
> ...


He only touched one part to the coax coming from the 722 (while it was plugged into the power socket) and another to an empty socket's ground.

He then used one of those little tools with 3 lights that you plug in to see if the ground is working properly, and it was for the 3 he tried.


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## harsh (Jun 15, 2003)

Diplexing cable won't hurt your satellite, but at some point it may interfere with your Internet service. DOCSIS 3.0 frequencies go pretty high. As noted above, the long-term solution is to not diplex the two signals.

The spark comes from voltage on the satellite leg. The second diplexer splits the DC off and sends it to the dish leaving the CATV coax at 0VDC.


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## P Smith (Jul 25, 2002)

blahblahblah65 said:


> He only *touched one part to the coax* coming from the 722 (while it was plugged into the power socket) and another to an empty socket's ground.
> 
> He then used one of those little tools with 3 lights that you plug in to see if the ground is working properly, and it was for the 3 he tried.


Had you seen was it center conductor or F-connector's nut ?


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## blahblahblah65 (May 23, 2008)

P Smith said:


> Had you seen was it center conductor or F-connector's nut ?


It was the wire coming from the middle...not the nut w/ threads

So, I know comcast wont fish wires through the wall. Is it possible to attach a long coax to the one currently in the wall, and pull that back to the central distribution point inside the house without cutting any walls? Or will insulation/bends in the construction make this virtually impossible....sorry i know nothing about construction


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## Grampa67 (Mar 14, 2005)

Do you loose the internet when the 722 is disconnected?


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## blahblahblah65 (May 23, 2008)

Grampa67 said:


> Do you loose the internet when the 722 is disconnected?


yup, it still goes up and down throughout the day


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## Wire Nut (Apr 6, 2012)

I think it will be easier to get a separate line from your dish to your main panel. Do this, then relocate your cable modem to another coax jack in the house. Or, if you have an accessible crawl space or basement, just run a coax underneath to the demarc box outside for cable.


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## blahblahblah65 (May 23, 2008)

Wire Nut said:


> I think it will be easier to get a separate line from your dish to your main panel. Do this, then relocate your cable modem to another coax jack in the house. Or, if you have an accessible crawl space or basement, just run a coax underneath to the demarc box outside for cable.


No crawl space underneath...so it sounds like I need to somehow figure out a way to get a cable from the panel in the laundry room (where each bedroom terminates and comcast comes in) to the outside entry point of comcast's wire on the side of the house.

Not sure how you could do this without tearing open the walls or running a cable out in the open.


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## P Smith (Jul 25, 2002)

get a mouse, tie a light thread to its tail, insert it into hole on back side of the panel ... she will find way out
then you will replace the light thread to something more robust and then pull coax with it


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## nmetro (Jul 11, 2006)

I have DISH for TV, COMCAST for internet. In my set up, Comcast only connected one cable to run to my home office to connect their service. My DISH connection, has two feeds only going to the satellite. Two other feeds are turned off. COMCAST placed a junction box at the point where the cables come from my house to a central point, in back of the garage. In no case, are the two systems are connected to each other. Though, it makes it easy to add more rooms to my satellite service in the future.

So, it sounds like whoever set up the service, described above, decided to merge both systems. Not only is this a bad idea, it could potentially damage the Comcast Internet Modem, equipment connected to the modem (most likely a wireless router) and affect the signal fro DISH, as well. Not to mention, it could damage DISH equipment. Two incompatible system requiring two different electrical requirements.

As others have suggested, either get a eletrician or have both DISH and COMCAST come out, at the same time, if possible, to straighten out this mess. If not, this could prove very expensive for any equipment connected via COAX.


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## harsh (Jun 15, 2003)

There is technically nothing wrong with diplexing and it does NOT necessarily risk equipment on the either side if done right (and it is pretty hard to mess up). There are two real issues:

1. Insertion loss (the more connections, the weaker the signal)

2. At some point, CATV may decide to run their voice or data services at frequencies >900MHz and that may kill your voice/data service.

Unless you're stupid or lazy enough to plug the CATV cable into the SAT port or only use one diplexer, you're safe from injected voltage on both sides of the diplexer pair.


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## bigglebowski (Jul 27, 2010)

"blahblahblah65" said:


> No crawl space underneath...so it sounds like I need to somehow figure out a way to get a cable from the panel in the laundry room (where each bedroom terminates and comcast comes in) to the outside entry point of comcast's wire on the side of the house.
> 
> Not sure how you could do this without tearing open the walls or running a cable out in the open.


At the distribution place is the house phone wiring there? Is it at least cat3 or cat5? Does one of the lines run to the room where you want the modem?

This is what i did, moved my modem to the other side of room (utility shed) from where all coax and phone lines go. Figure out which phone line outside goes to the room where router is and replace rj11 plate with a keystone rj45 jack. From that jack a 25' cat5 jumper ties it into my router.

In my case the phone wiring was cat3 with only 4 wires in it but thats all network wires use.


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## Michael P (Oct 27, 2004)

blahblahblah65 said:


> Everything with the following setup was working flawlessly until about 2 weeks ago. Internet started going up and down all the time and continues. Comcast tech came out and said everything is fine and then he disconnected the Dish coax coming FROM the VIP722, when he disconnected it, and saw it spark against the diplexer while moving around. He said that's "bad" and could be causing the problem.
> 
> Setup is as follows:
> 1) Comcast & Dish outside coax *--->*
> ...


Question: Was the 722 plugged in when the co-ax cable was pulled? If so that is the voltage that controls the LNB's! The LNB cables should never be pulled when the satellite receiver is plugged in. Having the receiver "off" does not cut the LNB control. The receiver is not truly "off" it's in stand-by mode. The receiver gets periodic EPG updates so that voltage is present 24/7.

What is a cable company installer doing messing with the satellite's cables anyway? They are not qualified to work on DBS.

BTW My internet also acted in a similar way as the problem you had. It turned out to be my router dying. I disconnected the router and directly connected the modem (surf board) to my laptop and it works. I lost my broadband to the 622, but once I replace my router that connection should be back up.

Upon rereading your post, it appears you may be using diplexers to combine the LNB and cable for internet. That is the problem! I have a separate co-ax coming inside for the cable broadband. The only connection between the cable broadband and the 622 is via CAT5. ViP receivers can only use special diplexers made for Dish due to the complex signaling - they are not compatible with cable tv.


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## P Smith (Jul 25, 2002)

echo: post#6 ... post#11 ....


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## Wire Nut (Apr 6, 2012)

P Smith said:


> echo: post#6 ... post#11 ....


The spark is normal, the Comcast tech obviously shorted the cable against the receiver port. 
Replacing the diplexers should buy you some time blahblah, but it will only ever be a temporary solution and a poor one at that. nmetro said it best, somebody didn't do their job correctly by combining the two systems on one cable. I'm leaning toward it being the Dish installer as Comcast techs do not generally have diplexers on them. This is a tough thing to get fixed, should have been done correctly upon installation but unfortunately it is a zero accountability industry.


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## Michael P (Oct 27, 2004)

Wire Nut said:


> The spark is normal, the Comcast tech obviously shorted the cable against the receiver port.
> Replacing the diplexers should buy you some time blahblah, but it will only ever be a temporary solution and a poor one at that. nmetro said it best, somebody didn't do their job correctly by combining the two systems on one cable. I'm leaning toward it being the Dish installer as Comcast techs do not generally have diplexers on them. This is a tough thing to get fixed, should have been done correctly upon installation but unfortunately it is a zero accountability industry.


Comcast should never touch the satellite co-ax lines. If the diplexers were from the Dish installer than it's Dish that needs to come out and straighten thing out. If any damage is done to your E* equipment you would be responsible - not the cable guy.


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## bigglebowski (Jul 27, 2010)

Not recommending that you should fool with any type of coax with voltage on them for fear of damaging equipment but most receivers either Dish/Directv all have protection circuits for shorts. Even modern wall warts and such all have protection circuits rather than fuses to protect even against sustained shorts that may occur. 

Again not saying you shouldnt power down your equipment or that a short will never kill a receiver, just saying. Of course modern receivers do seem like they take an eternity to boot when you are standing there waiting


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## P Smith (Jul 25, 2002)

bigglebowski said:


> Not recommending that you should fool with any type of coax with voltage on them for fear of damaging equipment but most receivers either Dish/Directv all have protection circuits for shorts. *Even modern wall warts *and such all have protection circuits rather than fuses to protect even against sustained shorts that may occur.
> 
> Again not saying you shouldnt power down your equipment or that a short will never kill a receiver, just saying. Of course modern receivers do seem like they take an eternity to boot when you are standing there waiting


The rule is: if you don't know for sure, for 100%, is a device has overload protection, *DON'T ASSUME IT HAS* !
100% safe to treat it as *UN-PROTECTED* !


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