Spark coming from Coax

10702 Views 28 Replies 10 Participants Last post by P Smith, May 8, 2012

blahblahblah65

Discussion Starter · May 2, 2012

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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1 - 20 of 29 Posts

P Smith

· #2 · May 2, 2012

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

blahblahblah65

Discussion Starter · #3 · May 2, 2012

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...

P Smith

· #4 · May 2, 2012

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

blahblahblah65

Discussion Starter · #5 · May 2, 2012

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

P Smith

· #6 · May 2, 2012

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

VDP07

· #7 · May 2, 2012

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.

AZ.

· #8 · May 2, 2012

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?

Wire Nut

· #9 · May 2, 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.

blahblahblah65

Discussion Starter · #10 · May 2, 2012

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?

P Smith

· #11 · May 2, 2012

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 ?

blahblahblah65

Discussion Starter · #12 · May 2, 2012

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

was that voltage AC or DC ?

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.

harsh

· #13 · May 2, 2012

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.

P Smith

· #14 · May 2, 2012

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 ?

blahblahblah65

Discussion Starter · #15 · May 2, 2012

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

Grampa67

· #16 · May 2, 2012

Do you loose the internet when the 722 is disconnected?

blahblahblah65

Discussion Starter · #17 · May 2, 2012

Grampa67 said:
Do you loose the internet when the 722 is disconnected?

yup, it still goes up and down throughout the day

Wire Nut

· #18 · May 2, 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.

blahblahblah65

Discussion Starter · #19 · May 2, 2012

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.

P Smith

· #20 · May 2, 2012

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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