On 7/25/07, Manuel Kampert <manuel.kampert@xxxxxxxxx> wrote: > As my original explanations with detailed findings have not been allowed > to post to the list I will just put some letters and say that I have > found the root cause of this issue .. It seems that the diseqc signals > especially on the 17V transponders are such bad that the diseq did not > recognize them anymore. This became even more problematic with my new > machine and new PSU... Normally, for a LNB polarization control you use a 13/18v control voltage. In _all_ cases a DC-DC converter is used to generate the polarizer control voltage aka H/V control With a normal PC SMPS (with regards to PCI DVB-S cards, power is drawn from the PCI bus) there is usually 2 voltage rails that can be used to power the DC-DC converter. Usually the 5V rail is used normally on almost all cards, since it can source more current. To obtain a reliable 18v in most of the cases the voltage is pumped up to say 24v or 30v the conversion amounts to say around 5 - 6x. Now if your SMPS delivers a voltage lower than 5v, then the voltage to the polarizer also will drop. This is not the case with cards that have a SEC chip, ie they use an internal PWM regulator where say an additional higher voltage maybe generated to compensate for the loss. With this said, we have issues in other cases where we have aging capacitors, where the multiplier fails due to the aged capacitors. The best thing to do is check what voltage you have on the 5v rail on the SMPS of your new computer. Also check whether there is a significant difference between the old SMPS to verify this thought. If there is a difference, simply replacing the SMPS would probably help. Some wandering thoughts that flew by. _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
