You can find the repair manual on Zuesbtc
https://www.zeusbtc.com/NewsDetails.asp?ID=171Since most of the problems are dead chips you will need to use their tool or another tool that tells you which chips you need to inspect, you will also need a few more tools for that, Zeusbtc also have some video/written tutorials that can be found here >
https://www.zeusbtc.com/News.asp?Sort=REPAIR+TUTORIALSThe forum is full of great details as well, so if you have a specific question you can always ask in the mining support section.