[mythtvnz] LNB power with dual DVB-S cards

[Steven Ellis]

On Tue, July 21, 2009 5:08 pm, David Shepherd wrote:
> This had me stumped for a while so thought I'd record what I learned
> today for anyone else who needs it.
>
> I have 2 DVB-S cards in my backend.  A Hauppauge Nova-S and a SkyStar
> Technisat.  I also had a Zinwell/DSE Freeview DVB-S box plugged directly
> in to the TV. (I bought this when I cancelled Sky and before I got the
> DVB-S cards sorted out)
>
> I had the cable from the dish going into the Zinwell then from the
> Zinwell to a single power-pass splitter to each DVB-S card.  Everything
> worked fine, multi-rec from both cards etc.
>
> I just upgraded my telly to one with Freeview HD built in, so I no
> longer needed the Zinwell/DSE Freeview DVB-S box.  I also bought a all
> power-pass splitter because I was pretty sure that the Zinwell was
> powering the LNB.
>
> So after lots of connecting and disconnecting from splitters, probing
> with a multimeter and testing LiveTV, I discovered the following:
>
> 1) The Skystar Technisat card provides LNB power (~18V) all the time,
> even when not recording.
> 2) The Hauppauge Nova-S card provides LNB power ONLY when recording.
> 3) When feeding both cards from a all power-pass splitter stops BOTH
> cards from working (possibly overpowering the LNB?)
> 4) Using the single power-pass splitter works fine ONLY IF the Technisat
> card is connected to the power pass side and the Nova-S card is
> connected to the the no-power-pass side of the splitter.
>
> So it all works fine again now.

I've seen similar issues before.

It looks like the Technisat puts out a lot of power and if you use an all
ports power pass with a Sky or Freeview STB there are similar problems.

One other solution is to use a seperate power injector to power the LNB.

Steve

--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email   - steven at openmedia.co.nz
website - http://www.openmedia.co.nz