Uno Tuner unstable on DVB-S2 channels

[tealc]

Hi Everyone

I don't know if this is the next big VU+ issue, but I can't seem to find this problem anywhere else.
2 VU+ Uno boxes that were bought at the same time, being used in two different houses for the last 2 years or so, both suddenly have issues with DVB-S2 channels.

It is very simple to replicate the issue, all I need to do is gently push/tap the satellite dish and at every tap the SNR drops to ZERO / 0% and back up again.

Here are the facts.
All channels on DVB-S works and don't drop when tapping the dish.
All channels on DVB-S2 works, but signal drops to ZERO and back again in windy conditions or by tapping the dish a little.
It has been testet and replicated with several firmwares, drivers and images/original VU images.
It has been testet and replicated on three different satellite dishes at three different locations, also different LNB vendors.
Nothing has helped even a little, same anoying symptom every time.


Any experts on VU+ UNO hardware?
Could this be a power supply issue or maybe the tuners going bad and why is it only affecting DVB-S2 and not DVB-S?

Looking forward to you answers.

Regards

Tealc

 

[el bandido]

You do not mention what satellite(s) or what dish size you are using.

In general, DVB-S2 Requires more signal than DVB-S. A Dvb-S2 signal may appear to be more narrow than a DVB-S signal. Either get a bigger dish or precisely adjust the dish you have.

 

[tealc]

Thank you for your reply, but why should I state the obvious?
The basics are not to be questioned, as said they have been used with the same setups for more than 2 years. The dish is even bigger than recommended.
Also my 3-4 year old VU+ Duo still works fine with the setup, and also working when testing a third UNO bought later than the two failing UNOs.

The SNR on the channels are above 90%, they are rock solid until I tap the sat dish, every tap drops the SNR to 0%, which is why this is so very strange! (and I mean tap, to replicate medium windy conditions)
Even an SD channel sent on DVB-S2 has this issue, all DVB-S2 transsponders in fact, despite which satellite.

Hope to hear from anyone with a similar issue or someone who knows which part of the hardware is failing, it is for sure not a software, firmware nor dish&cabling issue.

Thanks.

 

[tealc]

Update on the facts, as I was too fast to convince my self the problem was all DVB-S2 on all Satellites.
Now I don't have all LNB brands confirmed yet, but here is what I know now, and it is really shocking to be honest.

First of all, this issue is currently only seen on THOR (0.8w) DVB-S2 channels, confirmed not being an issue on SIRIUS (4.8E).
2 Vu+ Duo boxes confirmed working with no issues what so ever, just to have this fact to compare the Uno boxes to.
3 Vu+ Uno boxes confirmed having the issue mentioned above on 4 satellite dishes, but working on 1 (smaller) dish.

Here are 4 combinations that are confirmed being an issue on all three Vu+ Uno.
Dish1 - wave frontier t55, with Inverto Black Ultra QUAD LNB connected to 4-port Diseqc
Dish2 - wave frontier t55, with Inverto Black Ultra QUAD LNB connected to 4-port Diseqc
Dish3 - wave frontier t55, with Inverto QUAD LNB (not black, they are white) connected to 4-port Diseqc
Dish4 - wave frontier t55, believed to be Palcom 0,1db QUAD LNB (LNB brand not confirmed) connected to 4-port Diseqc

Now the last combination which works on all three Vu+ Uno, without being able to reproduce the issue mentioned in my first post.
Dish5 - Triax TD64, with Megasat Diavolo Twin LNB connected to 4-port Diseqc

This is really hard to crack, it also seems it has been getting worse within the last couple of month. (maybe changes were made on THOR sats)
From the combinations above, it's not easy to determine what makes the difference when it works
Is it the Triax TD64, the Megasat LNB or the fact it is not a QUAD LNB or the combination of it all?

Hope to hear from anyone with the same findings or at least someone who can test and confirm this issue.
Just connect a QUAD LNB (inverto looks like a safe bet to fail) on THOR(0.8w) and lock in on a DVB-S2 transponder, then disturb the dish with gentle vibrations and see SNR drop to nothing!!!

Thanks

Tealc

 

[lxch063]

As per discussion on another forum problem could be Capacitor C848 1000uM/10V - this could be replaced.
I have exactly the same issue and going to replace it Today.

 

[Matrix10]

Have you looked interference from vertical transponder
and other transponders with spectrum analyzer
I have examined a similar occurrence at 16 E
and the problem was vertical transponder.
(It is solved by provider. How, I do not know)
Why
Because each tuner has an automatic frequency control for minor frequency corrections
if present interference then tuner trying to find the correct frequency in this case can hardly find because they are both on the same transponder and frequency only different polarisation (tuner went the real frequency/tuner goes from the real frequency)
and loses signal lock and the SNR drops to 0
It is possible that some LNB have better insulation between the vertical and horizontal polarization,
and gives better stability to tuner.

I think that's the problem.
Which explains the above written observations.
I think maybe it is possible to get some of the kind minor improvements
changing the angle of the LNB.

So I think the problem comes directly from the satellites and transponders
in combination with LNB / TUNER
primarily due to interference.

Solution is probably a good choice LNB with good insulation between the vertical and horizontal polarization.

Of course multi-feed antenna have worse H / V isolation also worse weakening satellites out of focus (reflections)
and that it contributes to the problem.
The same applies to the use of multi LNB and multiswitch
compared to a standard antenna with a single LNB.
All this contributes to poorer isolation between the wished and unwanted signals
which affects the stability of the frequency tuner.

I do not know maybe VU + has the option to correct the work of automatic frequency control, which in this case should react slower
What might be helpful solutions .But of course I'm not sure 100%.

 

[Matrix10]

Just connect a QUAD LNB (inverto looks like a safe bet to fail) on THOR(0.8w) and lock in on a DVB-S2 transponder, then disturb the dish with gentle vibrations and see SNR drop to nothing!!!

It just happens because the useful / preferred signal is weakened at the expense of the interference.
Then comes into action automatic frequency control which loses lock by changing the frequency of the tuner
which further worsens the SNR and quality of the preferable signal.

Maybe you should write to VU +
Perhaps they have a straightforward solution,
despite the fact that it is a problem outside receivers.
If it were not so would be present at all the satellites and frequencies.

 

[lxch063]

Check if your problem is on DVB-S2 8PSK channels only. Regardless of HD or SD. If so, then solution is, as I wrote upper, replacement of Capacitor C848.
I had problem, that DVB-S2 8PSK channels were not able to load - AGC 91% and SNR flapped between 76% - 0% -67% and finally to 80%. It tooks about 10 seconds to have finally channel on. I repleced C848 by 1000vF/10V 105C and now everything works.

 

[tealc]

Hey Guys

Thanks a lot for your inputs, I have now had some extra time to test even more and I was surprised by the results a bit, but pretty close to what I expected.
First I want to conclude that the issue I have only happens when using any of the three VU+ UNOs I have, so I'm not blaming any of the LNB brands I mention below.

@lxch063 : Your problem sounds a little different from mine, but it is maybe worth investigating if changing the Capacitor C848 would solve my issue completely.
I really hope to find the end solution, instead of a "workaround" - which I will get back to.

@Matrix10 : Your explainations really inspired me to try some more testing, as I knew from my first tests, that the channels failing are on the same frequency and only differs with H / V polarization.

To recreate the issue try the following.
1. Connect VU+ Uno to one of the following LNBs

a - Inverto Black Ultra QUAD LNB" on THOR 5/6 at 0.8w
b - Triax QUAD TQD 004 - Partnumber 304414
c - Triax Single TSI 001 - Partnumber 300404
Info - If you have other Triax or Inverto LNBs, maybe the same applies.​

2. Make sure LNB is rotated to most optimal position. (you could use another receiver to calibrate the LNB)
3. Using Satfinder in UNO lock onto one of the following transponders

a - 10903 V DVB-S2 8PSK SR 25000 FEC 3/4 (notice. a and b differs only on polarization)
b - 10903 H DVB-S2 8PSK SR 25000 FEC 3/4
c - 10778 V DVB-S2 8PSK SR 25000 FEC 3/4 (note. there is also a DVB-S transponder on 10778 H, not tested)
Info - Have not tested all DVB-S2 transponders, but I can confirm one that currently works without the issue.Info - it works on "12015 H DVB-S2 8PSK SR 30000 FEC 3/4" and according to lyngsat.com there is no transponder on "12015 V"​

4. Try gently or moderately push the satellite dish and see SNR drop to ZERO / 0 on every push and notice the LOCK is also lost.
5. If you can't recreate the issue using the exact same steps, I guess the reasons could be one of the following.

a - Your VU+ Uno is a newer HW revision or another Tuner.
b - Your satellite dish is not a Wave Frontier T55 (severity of interference could differ.)
c - Geographic parameters could play a part, when it comes to severity of interference.
d - You did something different
​

My current "workaround" is
1. Connect VU+ Uno to the following LNB

a - Megasat Diavolo Twin LNB on THOR 5/6 at 0.8w
Info - Would like to know if all Megasat Diavolo SINGLE/TWIN/QUAD solve the problem. (I will soon receive some new TWIN and QUAD Diavolo LNBs)​

2. Make sure LNB is rotated to most optimal position. (you could use another receiver to calibrate the LNB)
3. Using Satfinder in UNO lock onto one of the following transponders

a - 10903 V DVB-S2 8PSK SR 25000 FEC 3/4
b - 10903 H DVB-S2 8PSK SR 25000 FEC 3/4
c - 10778 V DVB-S2 8PSK SR 25000 FEC 3/4​

4. Try gently or moderately push the satellite dish and see SNR is ROCK solid and the problem has gone away.
5. If it still fails with this LNB, try rotating the LNB a bit to see if it helps. I can also make it fail with this LNB if I rotate it way out of normal position.


As I said I'm a bit surprised with these results, mostly I'm surprised that a simple LNB like "Triax Single TSI 001 - Partnumber 300404" also makes the UNO fail on the transponders above.
But I'm also glad to see it can actually work with the Megasat Diavolo LNB.
It seems clear now that the problem only appears on transponders using same frequency, but with different polarization. (This is probably the outside parameter that has changed since I bought the Uno)
What I had hoped was to solve the problem just by rotating the LNBs into a "perfect" position between Horizontal and Vertical polarizations, but I have tried this with no luck on the other LNBs.
Some might question if the problem is more likely to happen on a satellite dish like the "Wave Frontier T55", I have not yet tried the other LNBs on a "normal" type of dish.
Anyhow, the main factor in all this is really the VU+ Uno or maybe just the stock Tuner it comes with, VU+ might even be able to solve this with Firmware and driver updates, who knows!

My wish is to fix the problem with the Uno receiver, not using the workaround and hope the symptom never reappears again.
I hope this info helps others or helps getting someone closer to a permanent solution.

Regards

Tealc

 

[gait33]

Check if your problem is on DVB-S2 8PSK channels only. Regardless of HD or SD. If so, then solution is, as I wrote upper, replacement of Capacitor C848.
I had problem, that DVB-S2 8PSK channels were not able to load - AGC 91% and SNR flapped between 76% - 0% -67% and finally to 80%. It tooks about 10 seconds to have finally channel on. I repleced C848 by 1000vF/10V 105C and now everything works.

Exellent job!!! It works!!! Tank you very much!!!!!

 

[Cojayar]

I had also the same problem. Adjusting the antenna was not helping. And all other two satellite receivers that I use with the same antenna did not have problems.

Finally I decided to replace capacitor C848 by one that supports 105°C (1000vF/16V) and it works like in the past.
ARD, ZDF, NDR, BBC, etc. now lock quickly and with good quality in the HD channels.

A 30 cents piece causing this much trouble. All in all it took one hour to solve it. After many hours trying different channel set-ups, searching for channels again, adjusting the antenna, etc.

 

[stutoni]

Have the same problem on my vu+duo2.Exactely same problems as you describe.Only using 1 sat position 0.8w with quad lnb from triax. Also new triax antenna as i have tried everything.New cable also.I have my vu+duo in second room and no problem there.
I will now try your workaround from Tealc and hope it works.
Thanks from Norway

 

[Cojayar]

A little bit than a year later the same problem all of a sudden. No single HD channel works.
I have changed again the C848 but it does not help. It must be another one.

I have found following list of potential problems:

C812 1000uF/10V
C819 1000uF/10V
C848 1000uF/10V
C816 220uF/16V
C843 220uF/16V
C860 220uF/16V
C264 220uF/16V"


But I do not want to change all of them. Shit.
Time to get a new receiver?