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[tioschris]

Hi,

We have been having issues with a adsl line for a long time now getting a lot of FEC and HEC errors.

Basically we've had zen get bt out that ended up being a personal friend, so he was able to skip the usual rigmarole and got a REIN engineer out within 30 minutes.  He used the mimtel 444b rf tester and eventually it turned out to be two circuits of lighting. We cannot turn these off permanently as staff would not be able to work.

The problem is there is roughly 240 led 240v (was halogen) down lights.  It wasn't every one causing the issues with the 444b, i've pulled the ones I can remember.  However now an engineer is offsite I cannot locate the faulty lightbulbs causing the REIN.  I've tried using a cheap radio from amazon but need something to try and find the fault that is not expensive and lets me isolate which bulbs of EFI issues.  The minute I turn the two circuits off the problem near enough goes away (there is more of these bulbs upstairs but doesnt seem to cause no where as many FEC/HEC issues with them turned.

The problem G10 bulbs where from ledhut.

Any ideas?

Thanks,
Chris

[JGO]

If some of the interference is entering the modem via the 50Hz supply then a line filter (with 13 amp P&S ) should reduce the effect if not dropping it below the normal noise.  These are available fairly freely.  ? Maplin Electronics.   A filter at the offending lights would be better but probably more of an undertaking, and more expensive to try on spec.

Otherwise, have the normal isolating of ring wire and 'phone extensions been applied ?  If not suggest a filtered faceplate like the  ADSL nation NTE 2005.   

Yes this is attacking symptons not the source but I seem to remeber that this happens to some led bulbs as they grow old. The thought of going round 240 bulbs whenever one decides it is old sounds like a bad joke.


 

     

[tioschris]

Not tried any filters other than wrapping ferrites round cat5, dsl and power cable going into modem (tried different modems).  When you say line filter what are you referring too?

A filter at each light would be very expensive!

It's plugged into master socket no extensions with faceplace removed ie. no bell wire.  Problem existed for bt engineer when he used crocodile clips on his dsl filter into there test device.

It is a serious joke and have been searching up and down about EFI / RFI interference but cant find anything cheap to help me, I really dont fancy spending £275 on the mimtel 444b that bt used!

[JGO]

" Not tried any filters other than wrapping ferrites round cat5, dsl and power cable going into modem (tried different modems). "

I don't like ferrite filters - firstly because  the cut-off is very gradual and secondly no one ever specifies the core size or the grade of ferrite they used !  Someone at GPO interference Lab once measured a guaranteed attenuation of all of 2 dB !!!  - long story.

" When you say line filter what are you referring too? "
LC filters suitable for a domestic appliance often with 13 amp P&S connections i.e. easy to fit and about £10. Caution;  some are designed for Long and Med Radio only so attenuation below 150 kHz may be poor - say what you wan't it for (and try getting it sale-or-return).
Try RS Components.

 

"A filter at each light would be very expensive! " Agreed ! 

"It's plugged into master socket no extensions with faceplace removed ie. no bell wire."
OK.

"It is a serious joke and have been searching up and down about EFI / RFI interference but cant find anything cheap to help me, I really dont fancy spending £275 on the mimtel 444b that bt used!"

Unfortunatly cheap equipment can cause you to waste weeks !

Good Luck

[burakkucat]

It is a serious joke and have been searching up and down about EFI / RFI interference but cant find anything cheap to help me, I really dont fancy spending £275 on the mimtel 444b that bt used!

My receiver of choice in such a situation is an ICOM IC-R5, sadly no longer manufactured.

[tioschris]

How would you use the ICOM device is the aerial that comes with it enough to pit a faulty led bulb (far few on ebay so may be worth it if realible detection methods).

[Berrick]

I can see this being an ongoing problem with GU10 LED bulbs, certainly the cheaper ones. There's barely enough room for the switch mode PSU let alone any filtering. So whilst it may be more expensive short term it may be cheaper long term to use a different LED lighting solution, MR16's with a clean 12v supply?

Alternatively you could always create a new office activity; F.I.B Find Interfering Bulb.

[tioschris]

Not really as that would mean getting electrition in to refit everything not really an option, in order to put proper fix in I really just need a reliable cheap way to detect faulty bulbs, then we can replace them with more expensive ones and check regularly as they fail.

[JGO]

If your prime concern is identifying faulty bulbs it may be that a simple field strength meter/absorption  wavemeter, from an amateur radio store would do. Much cheaper than £275 !

It would probably need to be held close to the offending bulb and it would help if your friend could tell you more about the interference he found - is it fairly narrow bandwidth ? ( I think Plasma oscillation is but I only met it once in several years working with gas tubes ) and if so frequency region ? If you still had a bad bulb that could be used to gain some experience but if it is bothering your ADSL then it must cover the 0-1 0r 0-2 MHz region for ADSL1 or 2+ respectivly.

[burakkucat]

How would you use the ICOM device is the aerial that comes with it enough to pit a faulty led bulb (far few on ebay so may be worth it if realible detection methods).

It comes with a rubber-duck antenna and I find, when monitoring frequencies in the 300 - 600 kHz range, it works best by "pointing" with the antenna -- rather like using a "sonic screwdriver". 

[tioschris]

Managed to resolve the fault the first time probably more out of luck switched about 2-3 led bulbs and resolved problem.

However, it's back with venage again.  I cant replace ever bulb in the building as we have way too many of them.

I did buy a second hand Icom IC-R5 but struggling to even find the REIN on it even know its definitely there!  Tried 306 KHZ (although shows as FM not AM not matter what you try) 612 KHZ shows fm but nothing around it.  I have turned squelch off and the use ferriate option is it user error I do find using the scanner very hard not used to older technology!

Thanks,
Chris

[JGO]

I think you may be looking in the wrong place !

AIUI plasma interference is a relatively narrow band emission, NOT REIN which seems to describe electrical noise from a motor etc which repeats every few kHz say for a long way ( Car ignition REIN used to extend to 45 MHz plus.)

If so you need to find it. "Look at 612 kHz 'cos it is a quiet spot" works for REIN but it doesn't work at all for RFI at say 3.7 MHz +/-  20 kHz. You need to sweep the whole ADSL band and a bit outside it to be sure. What system are you using ADSL 1, 2 or 2+ ?  ( Please not VDSL !)

Finding the approximate frequency region,( all bulbs won't be identical) is the first step to a cure.