used 800HD se replace oscam no problem anytime, when i bought zgemma H8 combo want test new oscam not work.
my way do like that
1, install image openatv 7.3 to H8 combo first
2, Copy OpenATV_softcam_feed_v9.0.ipk or softcam-feed-universal_4.8-r0_all.ipk to /var/volatile/tmp , then go install...