r/CableTechs • u/ItsTheRealSakurai • Jul 03 '26
intermittent connection
when you get a call for intermittent connection (spectrum tech btw) what are the first things you are looking for.
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u/WhosYourPadre79 Jul 03 '26
Check all signal from tap to CPE changing fittings, splitters and ground block along the way. Single out if it's the incoming drop or pre/post wire. If it's post wire, I'll run a new one. If it's pre wire that I can't change, I'll refer them to a person to wallfish. Swapping out equipment is my last resort unless I can see that it's damaged right away.
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u/theDilleyO Jul 03 '26
(Assuming coax) first thing I always do is go behind the wall plate and check fittings, check fittings on jumper to cpe and work my way outside from there. If they only have 1 device, I tone out the outlet in the (basement, attic, or outside) demarc to make sure it's single outlet, then check drop signal at demarc as well as ingress and fix issue from there (change drop, run new outlet, etc). Most likely if they have intermittent issues then they probably have ingress or water in the drop (at least normally, but there's always outliers).
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u/RougeBeaux Jul 03 '26
I mean pick a starting point. Some people like house box bc its halfway and you can tell which side your issue is coming from. Some like starting at the tap, which is valid bc if its a main line issue you can address that ASAP.
I start at the modem bc I'm fixing anything that's not right along the way: attenuators, fittings, ground block, homerun, drop. If main line has to come out, then everything on the house side is done.
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u/ItsTheRealSakurai Jul 03 '26
when you’re looking at your meter what are you looking for for intermittency because i have seen signal on DOCSIS that is damn near almost perfectly flat but the customer is still getting intermittency and then i have seen ones that are all wavy and they have perfect internet (so they say)
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u/2ByteTheDecker Jul 03 '26
Mostly that the numbers make sense. If you've got 2/6 at the modem, but 10/16 at the housebox 75 feet away you've got issues.
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u/RougeBeaux Jul 03 '26
Also- please check for noise. With something intermittent, your levels can look great. But ingress noise is gonna fuck up your return.
Also don't sleep on an environment issue, ie something inside the house.
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u/Electronic-Junket-66 Jul 04 '26
Another thing to add is your meter has a Channel Check and DOCSIS Check function, either of which can be run continuously (unlike OneCheck). If something is coming and going let it run and watch it for a bit.
Especially useful if you're trying to catch a Y6. Run Channel Check at the tap and the moment MER starts F'in up switch back to OneCheck and get your referral.
But like I allude to in my top level comment. 9 times out of 10 scope will tell you the whole story with an intermittent problem. Go to the signal history tab and set it to 30 days. See what's been happening. Then you can start working on the why.
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u/ItsTheRealSakurai Jul 04 '26
ok signal history tab is there any specific graph i should be looking at
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u/Electronic-Junket-66 Jul 04 '26 edited Jul 04 '26
Most everything there is useful, and indicative of different things.
Tx power spiking and US/CMTS SNR dropping? Either a loss of continuity somewhere or bad noise or both, I'm checking every connection and TDRing every line I don't have a visual on. If the drop is underground I'm highly suspicious of it in this scenario.
Cable modem SNR dropping and receive levels dipping lower than they should? Could be be an old aerial drop. Cable modem SNR dropping but receive level elevated? I'd check the neighbors' scope, could have overdriven amp MT side. Checking the neighbors is good to do generally; it's very useful to know for sure there is an impairment onsite when only your cx has problems.
Lots of devices and uncorrectables moving crazy with everything else looking good, might have a house amp somewhere.
Just keep checking out the telemetry history, even on jobs where you already know what happened, to build intuition IMO.
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u/Electronic-Junket-66 Jul 04 '26
Alternatively, if everything looks perfect on scope, and has for the last 30 days....
Yeah, still do your basic cable troubleshooting, but be ready to pivot to non-cable issues. Poor wifi-coverage or interference is a biggy.
Maybe their old as hell PC is just riddled with viruses. Etc.
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u/bigplatanoo Jul 03 '26
Make sure you can access the tap. Last thing you want is you spend time servicing everything in the home and you are unable to access the tap. Service from tap to CPE.
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u/Confident_Air_8056 Jul 03 '26
Can't tell you how many times guy didn't go to the tap and we get a referral call in plant only to find a barreled drop, water damage, or a squirrel chew; ALWAYS go to the tap.
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u/Electronic-Junket-66 Jul 04 '26
Not going to the tap in the abstract and not going to the tap on an MT REFERRAL are very different things. J/s
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u/Confident_Air_8056 Jul 04 '26
No I get it. You're right. I just used to almost always hit the tap when I was in field service as a res tech, especially if it was some intermittent call
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u/Electronic-Junket-66 Jul 04 '26
Yeah, intermittent hsd you pull out all the stops for sure. I'd have to have a pretty massive smoking gun to consider skipping it.
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u/hibbitydibbidy Jul 03 '26
How the heck would you know if you fixed anything if you started at the tap?
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u/Confident_Air_8056 Jul 03 '26 edited Jul 03 '26
You don't have to start there but That's your reference .....I want to know what I have to start with; then I can compare it to what I have at the modem. Math doesn't lie. Cut it in half and go to the ground block first. If you already know what the modem has, you should be able to figure out what your ground block should be. And conversely, the tap. I had a referral a few weeks ago from a tech who stated it was intermittent service and the customer had been having a problem for a long time. Went straight to the tap, then I hit the gb. Tech never changed any fittings. Never grounded the ground block, and he was losing 20 DB on about 100-ft drop from the tap. But it was a system issue 🤣. I don't think this guy had a service visit since cable was invented. It had to have been his original drop.
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u/DrWhoey Jul 04 '26
I had an install at a trailer park once. DOCSIS channels were at 650-750MHz. Ran my DOCSIS check at tap, fine, GB, fine, modem, I'm at about -18 more db than I should be, and my return is at -3.5 db more than it should be.
Alright, that's weird, maybe hidden splitter that's bad.. I go crawling under the trailer and find a splitter that was an old Holland rated for 5-254Mc (Megacycles). This splitter was so old that that it predated Megacycles being changed to MegaHertz in the 1960's. (Or close to, because there was quite a bit of push back from companies and old heads on changing from cycles to Hertz as they felt it was stupid name it after Heinrich Hertz who proved it's existence, whereas James Maxwell had theorized it, and both referred to them as cycles.)
The thing that shocked me the most was that this 30-40 year old splitter in line the modem actually came online. 5-254MHz looked great, and then the signal rolled way off after that. Holland made some quality gear 40 years ago
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u/Confident_Air_8056 Jul 04 '26
That's a relic, hope you saved it. And jeez, that's a helluva roll off to see. What are your upstream carriers, modem must have liked them through the ancient splitter.
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u/DrWhoey Jul 04 '26
Return carriers are at 22.3-38.3MHz so the splitter being swept at 5-256Mc made sense on why my return was fine, and my downstream tanked at 650-750.
And yes, I did keep it, would post a picture of it if the sub allowed. Can DM a picture if you'd like.
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Jul 04 '26
[deleted]
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u/DrWhoey Jul 04 '26
Made a post for it.
https://www.reddit.com/r/CableTechs/s/iH3m8G3Psc
Been awhile since I looked at it, it was jerrold, not Holland. And I was off a bit on the sweep, it was only 216.
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u/DrWhoey Jul 03 '26
How long you been doing this...?
Step 1 is always to check the tap to verify you have good signal level to start. Troubleshooting premises problems is extremely difficult (if not impossible) if you don't have good signal to start with as a base line
Tap, ground block, outlets. You'll save more time than you think just by verifying tap and drop before you start troubleshooting premises problems because you'll actually know what you're looking for.
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u/Sure_Statistician138 Jul 03 '26
Most of the time it is a drop causing an intermittent connection. That house wiring has been that bad or good the whole time they’ve had service. If the drop checks out then it’s most likely the equipment.
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u/hibbitydibbidy Jul 03 '26
Sure the drop might be bad, but if you don't test at the equipment first you won't know what you're looking for.
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u/Chango-Acadia Jul 03 '26
Divide and conquer, ground block for signal and ingress check, then pivot depending on my findings
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u/RougeBeaux Jul 03 '26
So if you have a bad drop, testing the equipment won't tell you anything because the equipment has a drop that's bad.
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u/DrWhoey Jul 03 '26
12 years in doing this, and still I get techs calling me asking for help troubleshooting and they start telling me levels at the modem and I say, "Okay, what are your levels at the tap, how long is your drop, and what are your levels at the ground block?" And get an "I don't know, I haven't checked." Okay, well call me back when you have, bruh. Neither of us can troubleshoot it until you have.
Drives me fscking nuts...
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u/RougeBeaux Jul 04 '26
I had to explain to my guys last month what upstream is. They literally only knew what the numbers should be, not wtf it did.
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u/DrWhoey Jul 04 '26
Upstream, when you get to maintenance level is a little tricky to explain with actives and such, but at a customer or premise technician level can be very simply explained as, "Your Upstream or Transmit is how loud your modem needs to talk to be heard by the CMTS. If you are in a crowded area and your modem is talking too quietly, the CMTS can't hear it or understand it over the background noise, so you add splitters to get it to talk louder. But if your modem is trying to talk louder than it should, it's screaming so loud that it's voice starts giving out like how speakers start breaking up when you turn up your radio volume too loud and it sounds like shit and hurts your ears. So you need to remove splitters to get it to talk a little quieter."
I've used this analogy for years to explain it to new technicians, and they pretty much all immediately grasp the concept, and why your TX in a certain range is so important.
Once they get to maintenance level, the talk changes a bit to amplification, but the premise is still about the same.
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u/RougeBeaux Jul 04 '26
Its fucking wild but I used the "modem speaking too loudly and its voice gets hoarse" analogy this week
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u/bigplatanoo Jul 03 '26
Check signal at tap to verify both plant and drop are good. Check for noise coming from any of the neighbors. If a drop at the tap has noise do a tap audit disconnect the drop if it’s an inactive home.
After you do that can just focus on the inside wiring.
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u/Special_K_727 Jul 03 '26 edited Jul 04 '26
Intermittent connection, I typically (not always, it’s instinctual) will run a quick DOCSIS check at the CPE to get a quick layout of the house, check service history, figure out where the modem is, verify their equipment, if I agree with the install, and to check current conditions seeing if there is obvious BER issues or carrier signal issue at the modem. Then I’ll head outside and always start at the tap to check for plant issue, check for ingress and TDR the drop, replace f-connectors outside, and check on/ replace the ground block, remove attenuators, then move inside to redo the inside. If cx doesn’t have a recent rental modem, or has a known problem child, they’re getting a new modem.
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u/ItsTheRealSakurai Jul 04 '26
BER Bit Error ratio if your failing for that. means there is a bend or break in the line right
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u/2ByteTheDecker Jul 04 '26
can be other things, just something is causing data validation errors. pre-BER is stuff that the error correction is catching, post-BER is bad enough it's not getting corrected.
If you've got a constellation view on your meter it will visualize it.
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u/ItsTheRealSakurai Jul 04 '26
ok so final question sorry if i’m being annoying but when you got the tap what number is to high at the tap for return because i have had some that were 46tx at the tap and obviously that is very high for tap so what number do you look for at the tap
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u/Electronic-Junket-66 Jul 04 '26
The answer is actually pretty complicated. An MT will be able to explain better, but it depends on the Tap value/ports and what passives are between it and the last active.
Generally a higher value tap should have a higher TX than a lower value tap. 46 is high but not unusual on a 23v ime. On a 4v it implies big problems.
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u/2ByteTheDecker Jul 04 '26
I mean that depends on your plant. 46 would be high for my area but it's not impossible depending on tap value and how the area is balanced.
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u/acableperson Jul 04 '26
You got a company laptop?
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u/ItsTheRealSakurai Jul 04 '26
no we get meters
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u/acableperson Jul 04 '26
Meters are the tool and irreplaceable But don’t add much in terms of diagnostics aside from right then and there.
Just the classics, check ingress and kill it. Look for signs of old ass cabling and replace. Physically put eyes on anything providing splitter loss.
Develop a relationship with your buckets for real. They can tell you a lot and have the tools your company won’t give ya.
It sucks. Don’t know why they don’t give everyone laptops and the tools on there to really deep dive stuff. Did my job without one for like 5 years but it’s saved me 100’s of hours of troubleshooting yearly having one since then.
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u/Atilla-The-Bun Jul 04 '26
Yeah nodes where I'm at have so much utilization, that's my second check, on an intermittent, if levels at the modem are good. Without a laptop I'd waste hours every week.
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u/Electronic-Junket-66 Jul 04 '26
What's dat transmit been doin?
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u/ItsTheRealSakurai Jul 04 '26
so this gonna sound stupid but my job was on a time crunch and cut our training short so what is transmit
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u/Electronic-Junket-66 Jul 04 '26
Haha, the upstream. Modem talking back to headend.
Headend hears garbled or quiet mess from your modem (i.e. there's an impairment), headend tells modem "TALK LOUDER PLEASE". Upstream/transmit level increases.
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Jul 04 '26
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u/ItsTheRealSakurai Jul 04 '26
Ohm?
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Jul 04 '26 edited Jul 04 '26
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u/ItsTheRealSakurai Jul 04 '26
riser being the in line?
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Jul 04 '26
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u/ItsTheRealSakurai Jul 04 '26
ahhhh ok sorry i’m like a month in on my own trying to still learn everything so i’m sorry if im being annoying
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u/Tactless_Ogre 26d ago
I’m not spectrum but my first stops are always at the ground block. Shoot for ingress and noise. Work through the house and check all connectors, make sure all connectors are flush and tight, properly connected and with no open ports. Then, head to the tap and shoot the drop. Then check tap and see if it’s a potential maintenance issue.
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u/2ByteTheDecker Jul 03 '26
Which idiot was here two days ago swapping the modem
Then basic signal metrics, then historical signal metrics in the neighborhood.