Channels freezing (SMATV system)

Rippy

I installed a sytem in a small apartment development (9 apartments) before Christmas.
Everything was hunky dory until a couple of weeks ago when one of the apartments started getting problems. Their digibox was freezing up on certain channels. Also badly pixellated.
Weird thing is they are only getting problems at night.

I measured the signal from the dish at the multiswitch and it was perfect.
Measured at the outlet in the apartment it was pretty poor.
Unfortunately the cables had been put in by the electrical contractor before I ever saw the job and were pretty poor quality on some of the runs (differnt cable used , but aluminium braided cheap rg6 on this one.)
Anyway, process of elimination- on a sucession of visits- I swapped the cable to a parallel unused line (same stuff, but you got to try....) ,changed the box,changed the mutiswitch (triax TMS 5/12) , installed an in-line amp on the cable , dis-connected the recently installed cheap and nasty front door camera modulator, changed the box again.... Am now at my wits end and no one seems to have a clue...

Seems to be no relationship between the channels affected , (some- but not all- are - RTE 1, NET 2 TV3 TG4 (10744H), Disney(10862H), ITV3 (10906V)
Discovery real time extra (11222H), Matinee/ Bad Movies (11343V), Golf CChannel(11389H), CCTV-9 (11662H).
No other apartments seem to be affected at all, and this is one of the shortest cable runs to the switch.
Any ideas folks before I have to change my name and leave town?

bigpaddy2004

You changed the LNB? Regardless whether or not your signal was fine.

Tony

I hope you fitted and earth bar on all the cables otherwise you really will have to leave town.

Rippy wrote:

I installed a sytem in a small apartment development (9 apartments) before Christmas.
Everything was hunky dory until a couple of weeks ago when one of the apartments started getting problems. Their digibox was freezing up on certain channels. Also badly pixellated.
Weird thing is they are only getting problems at night.

I measured the signal from the dish at the multiswitch and it was perfect.
Measured at the outlet in the apartment it was pretty poor.
Unfortunately the cables had been put in by the electrical contractor before I ever saw the job and were pretty poor quality on some of the runs (differnt cable used , but aluminium braided cheap rg6 on this one.)
Anyway, process of elimination- on a sucession of visits- I swapped the cable to a parallel unused line (same stuff, but you got to try....) ,changed the box,changed the mutiswitch (triax TMS 5/12) , installed an in-line amp on the cable , dis-connected the recently installed cheap and nasty front door camera modulator, changed the box again.... Am now at my wits end and no one seems to have a clue...

Seems to be no relationship between the channels affected , (some- but not all- are - RTE 1, NET 2 TV3 TG4 (10744H), Disney(10862H), ITV3 (10906V)
Discovery real time extra (11222H), Matinee/ Bad Movies (11343V), Golf CChannel(11389H), CCTV-9 (11662H).
No other apartments seem to be affected at all, and this is one of the shortest cable runs to the switch.
Any ideas folks before I have to change my name and leave town?

Rippy

Err... LNB cables are earthed but cables to apartments are not. Could that really be the cause..ony one apartment, only at night? Should I pack my bags Tony?

Tony

Rippy wrote:

Err... LNB cables are earthed but cables to apartments are not. Could that really be the cause..ony one apartment, only at night? Should I pack my bags Tony?

No dont pack you bags just yet the cable earthing is an electrical safety issue, there is and earth bonding bar you can get with f connections on it. HSA inspections are quite common now so I would do something on that front ASAP (if not done already of course) What sig levels in dbu are you getting at night when the problem starts ?

Rippy

Don't know what the levels are in dbu ( I really should invest in a spectrum analyser) but on my trusty wolsey sat meter i'm getting over 90 on PQ ,high and low band ,H&V. Sig strength is also good now I've fitted an inline amp.
Cannot see any difference in readings, night or day.

Electrical RFI a possibility?

byte

Hmm, you seem to have tried nearly every feasible angle. How close is the apartment to the head end? Like, would it be possible to run a length CT100 cable temp around the floor to the box, just to see if signal differs. It would help eliminate/blame the RG6 in the walls.

Another thing worth looking at, is there anything wireless near the box? I remember certain digiboxes didn't like to be in close proximity to DECT cordless phones for example.

Anyway, keep us up to date

Tony

I agree with Byte a temp cable would be a good way of proving where the fault is. A spectrum analyser really is useful in situations like this as you may have a poor signal to noise ratio which is causing errors, it really does not matter how strong the signal is if the noise is just below its level and I dont think the line amp will do you any favours in this regard.

Is a temporary test cable possible?

Rippy

I am going back there tomorrow night. I will try a temp. cable and I am also going to try to blag a loan of a spectrum analyser. The tenent of the flat phoned me tonight to say they had been in all day with the telly on and had no problems, until at 7.15 it went again.
A new cafe/bar has opened up directly below the apartment in the last month and I wonder if it is somnething in there getting switched on in the evenings causing it? Hard one to prove if that is the case.

bigpaddy2004

Could be interference from an electrical appliance such as a microwave as it does create harmonics in the 2.4ghz range.

Rippy

bigpaddy2004 wrote:

Could be interference from an electrical appliance such as a microwave as it does create harmonics in the 2.4ghz range.[/QUOTE

You never know, but surely if it was a microwave oven it would be intermittent and also during the day (place is open day and night) How about lights?

Zaphod

Rippy wrote:

Seems to be no relationship between the channels affected , (some- but not all- are - RTE 1, NET 2 TV3 TG4 (10744H), Disney(10862H), ITV3 (10906V)
Discovery real time extra (11222H), Matinee/ Bad Movies (11343V), Golf CChannel(11389H), CCTV-9 (11662H).

The 10744MHz (IF 994MHz) and 11662MHz (IF 1912MHz) could both be caught by a mobilephone mast. But it doesn't account for the others.

(courtesy of wrightsaerials.tv)

The only other thought that comes to mind was a case I read where a family were having problems every evening with some Sky channels. They tracked it down to the presence of their neighbour's BMW, who happened to have a speed camera detector installed, and every evening when he arrived home from work, their channels disappeared.

Rippy

The problem has now been found. Narrowed it down to a non-compliment piece of sh#ite dimmer switch that had been fitted in the cafe-bar below.
Every evening when they set the switch for the right evening 'ambience' the cable above gets a nice fat dose of RFI.
Am currently preparing a huge bill for wasted time.
AND I never got offered tea and biccies once!

watty

Ironically I think I mentioned recently someplace that the average person would get more RF from a bad Dimmer switch beside them a than a Mobile Mast in garden.

Glad you got it. Actually the Radio Museum in Cork was also getting hit by a fancy automated dimmer switch for display lighting.

Some SMPSU for minature power supply for 12V halogen track lighting meet EMC specs till you connect them. I guess the 12V wiring acts as an aerial.

Why don't more appartment blocks have properly installed shared distribution system instead of 20 or 30 badly installed minidish. I'm not sure how the multiple sat ones connect, but they would accomidate the Polish communities. (a lot of Cyfra Dishes on one block in Limerick:) )

byte

Good work! Glad you got it sorted

Now, I can envisage a person sitting at one of those calculators with till roll paper, and it reaming loads of figures!