If it has a conexant processor, there is no jtag program for it and you won't find a full jtag size dump. Conexant .stb files are over 900k, the usual sti5518 based .stb files are slightly more than 700k. If you expand the .stb file to bin with the program stbsplit, you will see the word conexant near the beginning of the file using a hex editor. If it has a sti5518 processor, you can jtag dump the defective flash and piece together a working jtag size dump with the expanded .stb file.
My Satellite Setup
Silvercrest SL65 80cm dish on Hotbird+MetronicEvo3 80cm on Hispasat PC: Prescott 3.0*3.4+3gb DDR+ATI HD 3850