How to diagnose faulty fibre?

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backfiah

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#265486 23-Jan-2020 21:42

We have a fibre connection running between the main house and a granny flat which has been working perfectly since June last year when it was installed. On Wednesday morning (about 4:30am based on the network logs) it suddenly stopped working.

I ordered a new media converter, and also a new transceiver --- got these today and tried them with no luck, so there goes $80. Also inspected the fibre in the roof and saw no evidence of physical damage --- all the outside fibre is in conduit.

What is the next step in diagnosis? Unfortunately don't have $100s to spend...

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#2405548 23-Jan-2020 21:56

remove the fibre both ends and put a torch at one end and see if you can see the light at the end ( I saw Chorus do this once )

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#2405550 23-Jan-2020 21:57

SATTV:
remove the fibre both ends and put a torch at one end and see if you can see the light at the end ( I saw Chorus do this once )

John

Higher Power torch the better as it removes the blockages ;)

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backfiah

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#2405559 23-Jan-2020 22:22

SATTV:
remove the fibre both ends and put a torch at one end and see if you can see the light at the end ( I saw Chorus do this once )

John

Ha. Seems so obvious now! Will do and report back.

sbiddle

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#2405567 23-Jan-2020 22:47

If you are removing connectors just be aware these should be cleaned before reinserting. Do you have the ability to do this?

Shining red light works best, proper LED testers are cheap but aren't going to help if you don't have one.

backfiah

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#2405597 23-Jan-2020 23:37

sbiddle: If you are removing connectors just be aware these should be cleaned before reinserting. Do you have the ability to do this?

Shining red light works best, proper LED testers are cheap but aren't going to help if you don't have one.

Compressed air or something more substantial?

sparkz25

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#2405603 23-Jan-2020 23:59

backfiah:

sbiddle: If you are removing connectors just be aware these should be cleaned before reinserting. Do you have the ability to do this?

Shining red light works best, proper LED testers are cheap but aren't going to help if you don't have one.

Compressed air or something more substantial?

Usually, Isopropyl Alcohol and lint-free wipes to clean the fiber.

And to test you would need a light source and a wavelength tester.

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sbiddle

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#2405628 24-Jan-2020 07:22

backfiah:

sbiddle: If you are removing connectors just be aware these should be cleaned before reinserting. Do you have the ability to do this?

Shining red light works best, proper LED testers are cheap but aren't going to help if you don't have one.

Compressed air or something more substantial?

Isopropyl alcohol and lint free fibre wipes as mentioned above or a fibre cleaning pen that will insert into the connector. I use a cleaning pen myself and you can pick them up for under US$10 from usual Chinese sources - just be aware you will probably pay about NZ$100 to one of the very same pens locally from a few big name NZ resellers.

It's really important that both ends of a fibre connection (cable and SFP end) are cleaned every time they are inserted / swapped. Even the tiniest speck of dust is enough to impact or even kill a fibre connection.

You can buy a cheap LED tester and power tester for under US$50 for a cheap kit. They're basically essential tools if you ever need to do any work with fibre.

Gordy7

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#2405655 24-Jan-2020 09:25

Isopropyl Alcohol in an aerosol can any good?.... would give the fibre ends and connectors a blast too...

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

Dugimodo

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#2405658 24-Jan-2020 09:39

Don't be blasting anything, a tiny amount of alcohol on the lint free wipe, then use a clean dry section to remove it. Don't re use the wipe either.

In a pinch the wipe will clean reasonably without the alcohol. You are just trying to gently remove dust particles, don't get too aggressive about it. Each time you wipe use a different piece of the wipe.

Remembering that fibre is finer than a human hair and a microscopic piece of dust can cover a lot of the connector surface.

The tester is called a glow tracer by our fibre techs, not sure a torch would work very well but maybe over short distances. You'd need near perfect alignment with the fibre end.

They don't tell you much about the condition of the fibre, just that light can get through. A Light source and power meter is better but these are tools you won't want to buy for a one of use.

Another thing is to walk the fibre route and look for signs of disturbance, and question anyone who may have touched the fibre and isn't owning up.... If anyone has bent it, or tripped over it, or hit it with the vaccum cleaner, etc they may have broken the fibre inside the cable and you wouldn't necessarily be ably to see any evidence of it.

who installed it? maybe they can test for you.

backfiah

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#2405674 24-Jan-2020 10:14

Dugimodo:

Don't be blasting anything, a tiny amount of alcohol on the lint free wipe, then use a clean dry section to remove it. Don't re use the wipe either.

In a pinch the wipe will clean reasonably without the alcohol. You are just trying to gently remove dust particles, don't get too aggressive about it. Each time you wipe use a different piece of the wipe.

Remembering that fibre is finer than a human hair and a microscopic piece of dust can cover a lot of the connector surface.

The tester is called a glow tracer by our fibre techs, not sure a torch would work very well but maybe over short distances. You'd need near perfect alignment with the fibre end.

They don't tell you much about the condition of the fibre, just that light can get through. A Light source and power meter is better but these are tools you won't want to buy for a one of use.

Another thing is to walk the fibre route and look for signs of disturbance, and question anyone who may have touched the fibre and isn't owning up.... If anyone has bent it, or tripped over it, or hit it with the vaccum cleaner, etc they may have broken the fibre inside the cable and you wouldn't necessarily be ably to see any evidence of it.

who installed it? maybe they can test for you.

Thank you (and everyone else!) for the valuable advice. A bit of a dumb question, but the end of the fibre connectors have "holes" in them --- I assume you don't try to wipe in the "holes", in which case what if dust has gotten down there? Or is it not as it seems?

I've checked the fibre route, since only a small part of it is unducted (in the roofspace). It looks fine...and hopefully unlikely to be human-caused since it died around 4am.

We installed it ourselves, so perhaps lucky it worked at all to start with! If I don't get anywhere, I might have to try and find a generous geekzoner or off-duty chorus tech in Wellington to bring their fancy tools for some beer money!

cyril7

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#2405676 24-Jan-2020 10:17

Holes? so a picture of what you are looking at please?

Cyril

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backfiah

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#2405677 24-Jan-2020 10:23

cyril7:

Holes? so a picture of what you are looking at please?

Cyril

Hm, maybe I was looking wrong...it was reasonably dark at the time. It looked to me like the LC connector had holes at each end, but googling it now it seems to be solid, which makes much more sense with the wiping etc.

Gordy7

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#2405711 24-Jan-2020 11:27

Do you have any spec on the fibre and media converter? (have a similar application in mind) Is there any diagnostics built in to the media converter?

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

backfiah

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#2405732 24-Jan-2020 11:36

Gordy7:

Do you have any spec on the fibre and media converter? (have a similar application in mind) Is there any diagnostics built in to the media converter?

I'm using fs.com gear: https://www.fs.com/au/products/75326.html https://www.fs.com/au/products/35333.html https://www.fs.com/au/products/50147.html

The media converter has LEDs that give some indication, but that's about it unfortunately.

Gordy7

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#2405753 24-Jan-2020 11:58

Maybe this sort of tester (or similar) could be useful:

https://www.fs.com/au/products/35389.html?country=nz&currency=NZD&paid=google_shopping&gclid=EAIaIQobChMI69a8q-ia5wIVGDUrCh2TQgGBEAQYAiABEgLrLvD_BwE

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

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