What is a DVR 758???
I will assume that you are talking about an Avtech DVR AVC758?
If yes then here is a manual located here:
http://scorpiontheater.com/cpcamtechsupport.aspx
This link is 10 megs. It may take a while to load based on the computer you are using. Just wait!
http://scorpiontheater.tech.officeli..._EMAP_V1.2.pdf
Take care,