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Direct download link to Samsung GT-S8300 UltraTOUCH service manual: (see flow chart of troubleshooting for schematics)
Samsung GT-S8300 UltraTOUCH service manual and schematics download
Here are lots of download links to Samsung GT-S8300 UltraTOUCH service manuals:
Samsung GT-S8300 UltraTOUCH service manual
Here is the collection of service manuals and schematics for more than 500 Samsung phones:
Samsung service manuals and schematics