Repair of a common problem with the Skystar2 V 2.6

Repair of a common problem with the Skystar2 V 2.6C DVB card from Technisat,the KuBand switch is not performed (22 Khz non working)

Herby my experience with a defective Skystar 2 DVB card.
The power converter on the Skystar2 card who converts the 12V PC voltage of the 13–19V power for the LNB is not overload protected and can easily be damaged by a shortcut in the coax cable or F connectors or a stalling or heavy turning DiSEqC motor. When the overload last long enough a coil in the power line becomes very hot and becomes defective.
This coil has to prevent that the 22KHz tone for the low/high band switching in the LNB flows into the converter instead of controlling the LNB band switch. With a damaged coil the level of the 22KHz signal on the coax is depending on the decrease of the inductance of the coil, so sometimes one LNB will still switch while another one stays at the low band.
Due to the overheating mostly some windings of the coil become shortcut so
decreasing the inductance of the coil. The voltage on the line is still correct, the polarisation switching controlled by the 13–19V on the line will still work, but the low/high band switching will fail. So only low band transponders will be scanned.
The coil can easily be replaced but is hard to get.
It is the black SMT coil, marked 102 on top of it and L7 on the PCB, above the tuner can close to the bracket.
It is a 1mH coil who must be able to withstand 500mA current.
At a local recycle shop for electronic parts I found a 1mH coil who could be placed instead of the original one, but this coil is not able to hold 500mA. When only a LNB and some DiSEqC switches are used the coil is ok, but when a DiSEqC motor has to be powered from the card the output voltage of the card drops too much.
De soldering the coil needs some experience with working with SMT components but can be done with a good soldering iron, not too big and not to small.
First put the heath on the connection point at the edge of the card and give with a small screwdriver a little lift pressure at the edge of the coil between the housing of the coil and the pcb. When the solder is melting the coil will lift a little from the pcb. Sometimes when the coil is cracked by the overheating the housing will break and that will make
removing the coil easier. Be careful not to damage the PCB by heating too long or giving to much pressure with the screwdriver.
When necessary remove the capacitor C5 between the tuner can and the coil first to reach the connection point of the coil on the other end. Be careful not to move the other small components as resistors and capacitors in the neighbourhood.
Sometimes lifting one end of the coil a little, and then the other end, then the first one again and so on till one end is free of solder, is the best way.
Be sure to replace the capacitor with the right polarity after replacing the coil.
The coil I used is not a SMT type but with the connection wires bend in the right way it can easily be used. When necessary you can connect a bigger coil with wires to the point on the pcb and leave the coil with isolated wires in the free.
On the next page a few pictures of a original card, a repaired card and a defective coil and the one I used as a replacement for powering a LNB only.
This is the way I did the job, I do not take any responsibility of problems or damage that might occur following what’s written above.

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