[linux-dvb] Twinhan VP-1030C Diseq problem SOLVED!

Remy Bohmer linux at bohmer.net
Sat Sep 1 22:59:59 CEST 2007

Hello All,

Several weeks ago we had a discussion on the linux-dvb mailinglist
about the Twinhan vp1030c clone cards and problems with Diseqc
switches which failed to switch between several LNBs. The conclusion
was that there was a lot of noise on the cable, more noise than
control signal for the Switch.

This was for me one of the reasons to buy a new Technotrend S-1500
card. BUT, it turned out that this card also has the exact same
problem with the switch as my Twinhan clone (Skystar 1 CI) card had.
This is the reason why I borrowed several brands of switches and LNBs
today to find out which part was causing troubles by replacing
everything piece by piece. The results I want to share which you all,
because it might help you, or others who read this and have also
strange problems with the DiseqC switch and PCI-receiver cards.

First some facts:
1. I have one dish, 1 x 4-port Diseqc switch, 3 LNBs, among 1 double
output LNB (1 output connected to the switch, the other to a separate
2. A standard receiver works properly with this setup. The Technisat
Skyastar 1 CI card did not. So, I searched the problem in the card.

Today, Eventually it turned out that the double output LNB was the
root-cause of all troubles. This LNB did not play well with the
switch, and this LNB caused all the noise on the line!
This LNB worked properly with another receiver, but NOT with both my
PCI-cards (Technisat and Technotrend card)

I would expect that the switch would switch off any LNB, but in fact
it doesn't, apparantly my trouble LNB does not want to be switched
Replacing this LNB with another brand (still double output) solved the
problem completely.

BTW: I noticed that the Technotrend card is much more stable than the
Skystar 1 CI card. Especially the CI interface hung quite a lot, of
the Skystar card, while changing channels. Sometimes even a hard-reset
of the complete PC was required to bring it back to life again. So,
the Skystar card will still find its way to the garbage...

Kind Regards,

Remy Böhmer

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