still no clear info ?
its either dm500s or dm500c or dm500t ?
(s) - satellite
(c) - cable
(t) - terrestrial
i think you also mean Russian C-Band channels at Express-AM3 @ 103° East ?
its unlikely to be a real issue that your box is a cheap clone since Dreambox 500 recievers have ceased support and this box years and years ago since there is much better available , but anyhow there still is plenty of clone-safe images on link i gave above .. but please try again with what your issue is and please be more specific with info that you provide .
Thnx