Hi
I have recently purchased a (Technisat) SkyStar HD2. I also have a (Hauppauge) Nexus.
I have a problem with my new Skystar which is not happening to Nexus.
I have a 4-port switch which has 3 satellites connected to it.
The problem is that if I switch from one satellite to another by selecting a channel on a Horizontal (18V) TP, the signal will be zero and I'll get a black screen. I have to tune to a Vertical TP (on recent satellite) and get back to the Horizontal TP to get the signal.

It does not happen when I switch to another satellite by selecting a channel on a Vertical (14V) TP.
It does not happen to my Nexus card (I connect them alternatively to the same switch, therefor I think it couldn't be a faulty switch problem).
It is present in both Progdvb and bundled DVBViewer.

I also measured the voltage of lnb out: H:18.78 V:13.88 (not under load)
any idea?

EDIT:
Just replaced the switch with a new one. It's working fine for now. I'll test it for a while.
It's weird that the old good nexus had no problem

Probably the reason is the strength of the LNB supply circuitry used.
Years ago, when the Nexus was designed, the LNBs drew far more current than today.

You should be thankful your Nexus did not wear out through the years, as many of those in fact do, 330 µF capacitor issue, often causing quite similar switching trouble...

BTW, in fact switches produce both, a DC voltage drop and a little extra current draw, by this reducing the voltage available for the LNB a bit. This can only be checked under load, directly on the LNB. But as causing short circuit on the LNB line can damage the tuner, this should only be done by an expert.

The LNB also matters, as the switching threshold may vary same as it's DC current draw.

To avoid such trouble completely, I've switched over to a mains powered multiswitch system years ago. This way, my tuners are loaded just by some mA by the extra DiSEqC switches plus the voltage detection stage of the user port of the multiswitch (used).

Thanks for your time

I live in Iran and possession of satellite equipment is a crime here! (but most households do )
because of that prohibition, the underground market is full of crappy and no-name equipment (LNBs, switches, ...)
It's hard to find a specific switch here. I think I have to stick to it.

By the way, I have connected my card directly to the power supply by its optional onboard power connector (4 pin peripheral power cable).

And can you direct me to more info about 330uf capacitor on Nexus. I took a look and it appears to be fine.

On many SS1 cards, that capacitor wears out. If so, it may get hot and it's cap is going to expand.
In any case, it must be exchanged for a low ESR version, 105°C 35 Volts, that is pretty hard to find, even over here in Germany.
Main problem would then be, to find a part, that's small enough, to not exceed the room available for one PCI card. Finding contact to the neighbour device would be really bad...

Another question: Can it possibly be a PSU issue?
My PSU is over 3 years old.

Normally not.

The SS1 eats around 11 watts (plus LNB power).
That's equal to one standard hard disk.
And the SS1 has it's own DC-DC converter, that could even compensate quite awful PCI bus supply voltage tolerances, beyond all tolerances.
As long as that capacitor is still alive...

With a weak PSU, your CPU and other hardware would surely suffer severely, long before the SS1 took any notice.

Regarding other DVB tuners, things should be almost similar, as they would also contain their own DC-DC converter stages, to provide the usual voltages for tuning, LNB supply and more.

Sorry for intruding this conversation.

I have the exact same issues with my TT 1600 S2 card. No or unreliable switching with my 4/1 Diseqc switch and no problems with other tuners and Skystar 2 card. I have tried many switches spaun, maximum, triax, EMP centauri, all with the same result.

I recently replaced my lnbs with the new inverto black ultra quad (high gain Lnb) and now I even don't have any signal anymore. (again : no problems with other tuners and skystar 2).

I intend to measure the current draw through the cable, i will have to prepare a little testcable for this though).

My and probably the poster question remains: How to solve this issue?
- powered multiswitches is not really an option outside (and very expensive for quad, i should have gone for quatro instead)
- Are there known DVB S2 card with high lnb currents? I read that the Skystar 2 has the external power supply but apparently still had this issue.

Thx