TV channels go blank when I turn on light switch

[Stevenfyeager]

A customer has this problem: Some of his bedroom TV cable (or dish) channels go blank ("no signal") when he turns on the bathroom vanity lights. Just the weaker channels go blank, not the local ones.
I installed two more TV outlets and power outlets in his house using a splitter in his attic. It is one of these that is acting up. I went back in the attic and made sure the new TV cables were not touching any 12-2 wiring. Still no luck. Any suggestions? Thank you.

 

[K8MHZ]

A customer has this problem: Some of his bedroom TV cable (or dish) channels go blank ("no signal") when he turns on the bathroom vanity lights. Just the weaker channels go blank, not the local ones.
I installed two more TV outlets and power outlets in his house using a splitter in his attic. It is one of these that is acting up. I went back in the attic and made sure the new TV cables were not touching any 12-2 wiring. Still no luck. Any suggestions? Thank you.

You do realize that there is 3 - 7 dB signal loss at each splitter, don't you? You may need some sort of an amplifier.

 

[GoldDigger]

If you have any unused ports on a multiport splitter, it is important that you put a resistive terminator on them. Same with the room end of any "spare" cables that are connected to a splitter.
A very small difference in signal to noise ratio on a digital signal can take you from a perfect picture to no picture at all.
The good picture you see with the light circuit off may be on the edge of maxing out the error correction capacity of the signal.

Sent from my XT1585 using Tapatalk

 

[Smart $]

I concur with both previous replies.

I've not dealt with any antenna since well before digital boradcasts, but previously it was preferable to use a distribution amplifier on the main antenna lead with enough outputs for every outlet... but in most cases, a 1x2 splitter after the amp will still provide a signal as strong as or stronger than the main lead.

 

[JFletcher]

If you spliced into an existing CATV cable to add 2 TV ports, you had to have used a 3 way splitter. There may not be enough signal to accommodate that further loss in signal. Are the terminations correct (compression fittings)?

As written above, cap off (resistive terminator) any unused coax wallplates. Do not cap off unused ports on splitters, replace them with smaller splitters. If that attic one was a 4 way with an unused port, putting a cap on it is *usually* a wash with using a 3 way, tho a 4 way has 4 7dB loss ports; a 3 way has 2 7dB loss ports and a 3.5. Use the 3.5dB port on the cable that is losing signal when the lights come on.

LED lights?

 

[zbang]

In addition to the excellent advice re splitters, does the vanity use incandescent, CFL, or LED lamps? If it's not the first, try different lamps; the cheaper CFLs especially can radiate some tremendous electrical noise.

 

[jjc122161]

I had the same issue with only one channel. It was the LED lights.

Sent from my SM-N910V using Tapatalk

 

[gar]

161210-1037 EST

jjc122161:

Tell us the brand and part number of the offending LEDs.

I have some Feit LEDs from Home Depot that oscillate in the middle of the AM broadcast band, 800 to 1100 kHz. These, a single one, put out enough radiation from the power lines, even from the primary side that I get noise on my car radio after leaving my yard. 120 or 240 from the secondary powers my street lights. From a street light where its power dead ends I can still go 100 to 200 ft and still get AM interference.

Some other LEDs have oscillation around 50 kHz.

I have not looked for noise at higher frequencies.

Driving by a home about two blocks from mine I get a lot of interference on the car radio. Could be LEDs in that area.

.

 

[hbiss]

A customer has this problem: Some of his bedroom TV cable (or dish) channels go blank ("no signal") when he turns on the bathroom vanity lights. Just the weaker channels go blank, not the local ones.

Just the weaker channels?? Not the local ones :? He has cable how do you know that they are "weak"?

I suspect that the cable wiring is a disaster and together with what GAR said you have a problem.

Tell your customer to call the cable or dish company to fix the mess.

-Hal

 

[K8MHZ]

Just the weaker channels?? Not the local ones :? He has cable how do you know that they are "weak"?

I suspect that the cable wiring is a disaster and together with what GAR said you have a problem.

Tell your customer to call the cable or dish company to fix the mess.

-Hal

The channels with higher frequencies have more transmission line loss than the ones with lower frequencies. The cable companies try to even out those losses but can't perfectly compensate for every single drop on the run, due to changing line (coax) resistance.

Even if all the channels are the same coming in, the high UHF channels will be attenuated by the home's coax more than the lower ones or any VHF frequencies used.

 

[hbiss]

The channels with higher frequencies have more transmission line loss than the ones with lower frequencies. The cable companies try to even out those losses but can't perfectly compensate for every single drop on the run, due to changing line (coax) resistance.

Even if all the channels are the same coming in, the high UHF channels will be attenuated by the home's coax more than the lower ones or any VHF frequencies used.

The OP tipped his hand that hasn't got a clue by mentioning weaker channels and local channels. Thirty years ago with an antenna on the roof those would be factors but where channels originate are immaterial with a connection to a cable system or satellite.

Cable systems operate today with a bandwidth of 55 to 1000Mhz. While technically that encompasses low VHF to high UHF frequencies as defined in the "old days", it's really a non-issue with cable since any channel could be assigned a frequency anywhere within that bandwidth and "mapped" to some number you enter on your cable box. So channel 2 as shown on a cable box could be at 800 Mhz and channel 300 could be at 55 Mhz. And while it's true that cable loss increases with frequency, without knowledge of the cable system itself and test equipment there is no way to tell if a problem with a particular channel is due to weak signal. Analog is no longer used and you could always tell a weak signal because of the snow. With digital it either works or it pixelates or it doesn't work.

Another situation that can cause problems is ingress. This is where an outside signal gets into the cable system because of poor connections or poorly shielded cable and disrupts a channel or block of channels. It sounds like this may be what's happening here. No offense to the OP but I suspect that the cable fittings may be improper or improperly installed as well as too many splits.

That said I'm beginning to get a real bad taste in my mouth about LED lighting and the huge number of weird problems it causes. It just might be that there is interference transmitted through the electrical wiring that is disrupting the cable or satellite box.

-Hal

 

[Open Neutral]

...when he turns on the bathroom vanity lights....

LED? With noisy as all get out switcher supply, perhaps?

 

[JFletcher]

Coax is shielded by design and proper installation will not allow ingress. That said, an open splitter port near a source of interference will cause problems. The original poster didnt mention tiling, freezing, pixellation, snow, or any of the other usual problems caused by too much signal loss, so my bet is also either on the terminations or uncapped splitter ports.

The correct tools to strip and terminate RG-6 with compression fittings can be had at big orange for around $40-$60 (Ideal, Klein). Not the best quality, and the compression fittings cost ~50c ea there (very high), but a stripper with the 1/4"-1/4" double cut and an in-line compression tool with the correct fittings is near cable-company grade when done right (they use PPC EX6XL fittings here; I use the EX6 ones about an 1/8" shorter; same fitting other than OAL). Crimp and screw on fittings are garbage; dont waste your time with those. Matter of fact, any you run across, replace them.

Still better to use a smaller splitter than cap unused ports. Properly terminated coax should basically be immune to a 9-26W LED or CFL light turning on.

IIRC, some splitters have different frequency ranges (standard are 1GHz, better are up to 2.4GHz, some go up to 3, maybe 5 GHz) they are good for. Also note that an RG-6 F connector will not work on RG-59 cable (thinner and usually identifiable by the copper vs steel/AL shield braid); they will be loose at best and a potential source of problems.

Home CATV is pretty easy. Cable comes in, hits a grounded 2 way splitter. One of those lines goes to the internet/cable modem. The other goes to up to an 8 way splitter, which would have 8 -15dB ports. It is best to use as few splitters as possible to prevent signal problems, and always use compression fittings.

Every split is a 3dB (half signal strength) loss tho due to design it's more like 3.5dB. Thus, a 2-way splitter will lose ~10% of the signal and send 45% to one port and 45% to the other (thus the -7dB markings on it). An 8 way loses ~20% and sends 10% (12.5% theoretical) to each of the 8 ports; -15dB ea. So you can see that using the smallest splitters vs termination caps on unused ports possible is prudent.

Properly done barrel connections and compression fittings have virtually zero loss. Crimp style F-conns are never installed correctly, and screw on are a DIY item for people w/o the right tools.

 

[ggunn]

I agree with all the above about bad connectors, splitters, etc. I have cable drops all over my house, and splitters were causing me problems even when it was all analog, so I got a video distribution amp and only had a 2 way spiltter on any line I split. This worked very well, even after my cable company went digital, but when I swapped my cable boxes for the type that does on demand stuff, the VDA was a problem since the boxes need to talk back to the server in the cloud. Without knowing if such a thing even existed, I Googled "bidirectional video distribution amplifier", and bingo, I got a couple of hits.

The bidirectional VDA solved most of my problems, capping open ports with terminators solved more of them, and replacing some wiring with double shielded RG6U and getting good connectors and an installation tool solved the rest.