LNB 13/18V missing

E

eppesuig

Member
My Satellite Setup
Dreambox 500s
My Location
Italy
Hello friends ,

i have problems with my Dream 500s .

The Q72 was defect and no channel could be found .

Afte replacing the MOSFET the problem still exists .

The reason is that the LNB Power (13/18 ) is missing , could some one tell me where/how the LNB-power is generated ?

What i have seen in the shematics is , that the 13/18 CTRL and the LNB Power Control come from the U15 .

Thanks in advance .

B.R
Gio :confused:
 
The main question is why did the MOSFET blow in the first place?

There could be something else wrong in the receiver, a shorted coax or a bad LNB or switch can cause hidden power supply damage, look for dis-colorization on the power supply's PCB, there could be over heated components that may be damaged.

Also look for bulged or over heated capacitors and diodes that may have been over heated and are not rectifying the AC voltage correctly, too much AC in the power to the LNB will cause all sorts of problems.
 
Q70 could be shutting down the MOSFET if it's short circuited.
 
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