My DVB-T Troubleshoot

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Nerdherder

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#128581 15-Aug-2013 12:47

I recently updated a few things in our AV setup, and moved our router/modem to a position hidden behind the setup, all at the same time.

The main crux was our DSE/Zinwell DVB-T receiver wasn't powering up properly, it would take 10-15m to get a signal, so we were leaving it on all the time, which was fine, until it is turned off and you want to watch something straight away.

We replaced it with a DishTV T1020, which will eventually be run as a stand alone recorder, since we also lucked upon a TV with an integrated tuner also. FWIW, I'm using the pass through on the dishtv at the moment for the aerial cable to the tv. I'm considering an amplified splitter, as the pass through cuts off when the T1020 is switched off! Grrr..

Problem: The Zinwell would read very high signal quality and strength on the TVNZ mux (95%+), reasonable on the mediaworks mux (85%) and reasonable on the "all others" mux (85%). Dropouts never occurred.

With the move, the reading of the signal given from the T1020 is significantly down on this. I understand that the readings will be different between different hardware, however now there are significant dropouts on TNVZ and it runs about 80%, Mediaworks pixelates often at 75% and from time to time signal drops to zero, and the signal on the 'other' mux is 56% or worse with regular drops to zero.

I have had a tech in the past but paid $150 to be told he could fix it for $500 with a different aerial. Uh, what?

We have a 43 element, just like out neighbours.We are less than 7k straight line from Waiatarua, and with trees in the way, but the aerial setup hasn't changed since the perfect reception, so am thinking it is internal to the house. Aerial cable is rg6.

My Trouble shoot will involve the following, and I will report back:

-Firstly replace the aerial cable terminal plug (has a Belling Lee lead between this and the tv, no possibility of stretching directly to the tv), the old wall socket has moved about in the changeover.

I understand a crimp is the best, will look if can see an affordable option, I don't know anyone with a crimper.

-Secondly turn off the cordless phone and wifi router which are close and see if they are causing rf interference. If so, upgrade the shorter aerial cables to shielded versions, the ones I have are of unknown origin.

I have noticed that the signal worsens when our dvd player is on. It is on the shelf above the T1020, so am wondering if this STB or aerial cable is sensitive to rf interference.

-Thirdly, I'm not quite sure, but either perhaps invest in signal strength indicator and up on the roof with ye, then either get an new aerial or try the amplified splitter to increase the signal or add a masthead amp. The powered splitter would suit our setup more than a masthead amp, needing two outlets for the aerial.

Can someone concisely explain how to separately improve the signal strength vs the signal quality? At the moment they
are about the same levels on the indicators, even when fluctuating.

Finally, apologies if this seems a nuisance or pointless, I did do a search for questions already posted, but this more a demonstrative thread, just hoping my mission assist someone, alternatively interested if anyone knows of an affordable tech out west...

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#878761 15-Aug-2013 13:13

Where in NZ are you?

In my experience the inbuilt TV tuners are the best. They tend to have great VHF filtering on the inputs, where as a lot of stand alone boxes do not respond well at all to any VHF being present.
Even UHF aerials to receive VHF signals and fitting a VHF/UHF diplexer inline can be a cheap way to test this.

Either way I would be looking to split the incoming TV signal properly via an external splitter, to ensure you can feed both the TV and the set top box directly, with no pass through configuration.

The zinwell issues were most likely a capacitor issue. I replaced some on a friends unit and it sprung back to life brilliantly, for a cost of $1 in parts.

Nerdherder

27 posts

Geek

#878782 15-Aug-2013 13:36

Doh! I don't have circuit troubleshooting knowledge so didn't attempt a repair, figured a new box would be the same as a repair cost, plus this box has series link capability.

I'm in West Auckland, near the Waiatarua antenna.

So saying external splitter, you mean the amplified splitter I was talking about, or just an unamplified splitter? Can be had for about $60 online, just not sure what db gain to get, as I'm not sure they are all adjustable. But unamplified ones provide a loss, which is contrary to what I'm experiencing..

Hmm, will look at a diplexer, thanks for the tip.

Sadly plugging direct to the TV from Aerial still results in pixellation/dropouts.

Gut is saying the socket at end of aerial cable, fingers crossed that is all it is anyway!

Jaxson

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#878842 15-Aug-2013 14:29

Nerdherder:

Sadly plugging direct to the TV from Aerial still results in pixellation/dropouts.

You have issues if direct to the TV doesn't work properly. Suspect the likes of:
Dodgy connection somewhere on the cable, any short will pull the whole thing down.
Failed connection at the aerial. - Is it an F connect on the aerial or an older saddle/clamp connection to it?
Wrong alignment of the aerial, either wind has blown it off direction or it was installed with the wrong orientation.
Poor location choice on your house.

Splitter, I was meaning an internal one, close to the first device/just along the line from the wall socket.
Something like:
http://www.itsavy.co.nz/2-way-satellite-antenna-splitter-h/

Diplexer looks like:
http://www.itsavy.co.nz/uhfvhf-diplexer/

Not advocating that store, that was just on the first page of the google search.

Either way though, you have bigger issues if a direct feed to the tv tuner doesn't work. Forget any additional items until that direct feed works.

Do you have anything else along the way, ie any older amplifiers in the line already that may have failed, or power supplies to them that may have failed etc?
Ideally you want a direct line from aerial to the TV, with no splitters to other locaitons/outlets etc.

You have to sort the base signal as best you can before thinking about an amplifier, otherwise you'll simply make a bad signal much louder.

Nerdherder

27 posts

Geek

#878850 15-Aug-2013 14:41

Thanks for the help.
The diplexer, which outlet do you use to remove the FM signal? The 0khz or the 22khz outlet?

I understand splitters introduce losses, so want the aerial to TV working brilliantly first before sorting out the final routing.

Yes I know the aerial setup and/or outside rf interference are the cause if the TV tuner isn't working. nothing has changed with the outside setup, it was moving stuff inside around that caused the issue, so I'm pretty sure the problem lies inside.

Tell you what, I'm going to try the old box in there and see if there is an issue with signal on it now, just to eliminate the TV or T1020 as causes.

Will also report back once I can get a new socket on the aerial line and test direct to tv, then with the wifi and cordless phone off.

Jaxson

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#878879 15-Aug-2013 14:59

Nerdherder: Thanks for the help.
The diplexer, which outlet do you use to remove the FM signal? The 0khz or the 22khz outlet?

I understand splitters introduce losses, so want the aerial to TV working brilliantly first before sorting out the final routing.

Yes I know the aerial setup and/or outside rf interference are the cause if the TV tuner isn't working. nothing has changed with the outside setup, it was moving stuff inside around that caused the issue, so I'm pretty sure the problem lies inside.

Tell you what, I'm going to try the old box in there and see if there is an issue with signal on it now, just to eliminate the TV or T1020 as causes.

Will also report back once I can get a new socket on the aerial line and test direct to tv, then with the wifi and cordless phone off.

I wouldn't be happy with the reliability of a system that was so borderline that a phone stuffs it up. I suspect you've been very borderline with your reception quality before and these new devices aren't quite as good at handling the weak signal they are getting.

0 and 22khz are satellite tone 'splitters' and are not what you would need. Diplexer wise I'd wait until you have something fairly solid to the TV before going down that route. What you may eventually want though is a VHF and UHF diplexer, in which case you'd only use the Output terminal and the UHF one. This would filter out any VHF and may improve things on the set top box, ONLY IF that unit is susceptible to VHF signals.

Nerdherder

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#878881 15-Aug-2013 15:04

Thanks heaps!

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B1GGLZ

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#878921 15-Aug-2013 15:51

Jaxson:

You have issues if direct to the TV doesn't work properly. Suspect the likes of:
Dodgy connection somewhere on the cable, any short will pull the whole thing down.
Failed connection at the aerial. - Is it an F connect on the aerial or an older saddle/clamp connection to it?
Wrong alignment of the aerial, either wind has blown it off direction or it was installed with the wrong orientation.
Poor location choice on your house.

+1
If antenna direct to the TV still gives problems then you have an antenna and/or cable problem. Movement of internal modems etc is probably affecting quality because of the external problems.
I have a similar antenna at Beach Haven about 10kn line of sight and get 100/100 strength/quality.
Your antenna system may have deteriorated slowly over time. I found with my previous antenna it got water in the balun /connector box which corroded the circuit board.

And you shouldn't need any amplification at 7km from the Tx.

P.S. I've had 2 Zinwells same as yours and they both died at 2 years old.

Nerdherder

27 posts

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#878937 15-Aug-2013 16:32

No amplification even if some trees in the way?

Agree, cable terminal plug problem highly suspected. The signal was fine until the current belling connector at end of aerial cable was moved around, I'm SURE it's the problem..

I'm not sure but it is hard to find a female plug for RG6, I suspect the end of the aerial should be Male f connector, then will need to have a female/female adapter in order to attach to a male/male cable (can't find any female/male cables) to attach to TV, correct?

Jaxson

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#878970 15-Aug-2013 17:27

Typically f connectors should be female on the cable. You would use a double ended male joiner piece to join two cable sections if required, or even a male f connector to pal plug adapter for use on the tv etc.

B1GGLZ

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#879002 15-Aug-2013 17:50

Nerdherder: No amplification even if some trees in the way?

Agree, cable terminal plug problem highly suspected. The signal was fine until the current belling connector at end of aerial cable was moved around, I'm SURE it's the problem..

I'm not sure but it is hard to find a female plug for RG6, I suspect the end of the aerial should be Male f connector, then will need to have a female/female adapter in order to attach to a male/male cable (can't find any female/male cables) to attach to TV, correct?

No amplification needed at that distance. I can get a picture here with a short piece of wire on the end of a short length of co-ax plugged in the TV, inside and with trees in the way.
My antenna cable terminates in a male f plug which plugs in the back of a skirting mount socket (female/female feedthrough) and standard male f plug to male Belling Lee cable from skirting socket to the Blu Ray Recorder passthrough to the TV.

Nerdherder

27 posts

Geek

#879261 16-Aug-2013 08:41

Frustrating night last night, am getting the cables and plugs today, so was mainly troubleshooting other possible causes.

Eliminated the surge protection board as possible cause.

Eliminated wifi and cordless phone as significant cause. Although it does cause a drop of 4% strength and 7% quality.

Eliminated the passthrough as possible cause. TV still pixelated straight through from aerial. Although the pasthrough does force a repeatable 3% drop in quality on the STB when plugging it through to tv.

DVD player/recorder, this I can't get my head around. I checked all the connections are to the right place. Turning the DVD recorder on doesn't affect the signal during boot up, but as soon as it gets to the point of spinning up the HDD and DVD spindle, the signal and quality on the Kordia mux drop to zero and stay there. Turn the DVD player off again, and the signal comes back. But, the TVNZ and mediaworks mux's seem unaffected.

Will be getting some shielded cables and f connectors today, and we'll see how we go over the weekend.

FWIW the signal strength and quality seemed to change depending how I held my tongue... Jiggling the brand new belling cable plug in the back of the STB seemed to significantly affect the signal up to like 10%. At times the Strength on TVNZ could go up to 97% and quality 85% and steady, but would have momentary freezes of image and audio, despite no change in the signal graph. Likewise Kordia mux could have 85% for S&Q, and then inexplicably every half minute or so you can see the graphs drop to zero, then recover.

At one point it was:
TVNZ 98%S 81%Q
Medwks 77%S 75%Q
Kordia 79%S 75%Q

Then without touching anything this morning TVNZ was down to 59% signal and 78% quality.

The search continues....

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Jaxson

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#879292 16-Aug-2013 09:26

As above, have you checked your actual aerial, with regards to orientation and termination connection quality etc?

Nerdherder

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#879297 16-Aug-2013 09:35

I'm replacing the termination over the weekend. Aerial hasn't changed from when I had awesome signal with the last box. The loss of good signal occurred on the same night I changed everything over.

I forgot to mention, I setup the old box last night and although it could find the mux's, it couldn't get enough signal to set the channels.

So def think the issue is inside, caused by moving stuff around/dodgy connections or interference. A bad aerial wouldn't explain the DVD player interfering with the Kordia mux, that is really confusing me...

I want to replace the termination and use shielded cables anyway, so once this is done, I will go up on the roof, check for corrosion etc (plugs are waterproof) and try to improve signal again, and report back.

The signal reporting on the t1020 is excellently easy to get to, under the channel info/program description, rather than having to go through the channel setting procedure like the last box. I will add my 2c about this box to the t1020 threads when this is done..

B1GGLZ

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#879306 16-Aug-2013 09:46

Nerdherder: Jiggling the brand new belling cable plug in the back of the STB seemed to significantly affect the signal up to like 10%. At times the Strength on TVNZ could go up to 97% and quality 85% and steady, but would have momentary freezes of image and audio, despite no change in the signal graph. Likewise Kordia mux could have 85% for S&Q, and then inexplicably every half minute or so you can see the graphs drop to zero, then recover.

At one point it was:
TVNZ 98%S 81%Q
Medwks 77%S 75%Q
Kordia 79%S 75%Q

Then without touching anything this morning TVNZ was down to 59% signal and 78% quality.

The search continues....

That would indicate to me there is definitely an antenna problem. That sort of thing happens when the aerial has become disconnected and you are receiving just with the co-ax cable connected. Also playing around with the inside equipment with just the co-ax and no antenna would cause the problems you describe. Get on the roof and check the antenna for bad joints and corrosion. At 7km if the antenna and co-ax is in perfect condition you must get 100/100.

Edit.
P.S. Also borne out by the fact you can't get a useable signal now on the STB.

Nerdherder

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#879327 16-Aug-2013 10:07

Is there any way I can check the coax cable is working fine/has no seperations or anything? Have and can use a multimeter, it is showing a circuit across the cable at the tv end.

Would be a pain in the arse to change though...

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