When running PSConfig (Configure Sharepoint Products) - the app stops at : document conversion launcher service
Resolution: Add the Key: AcknowledgedRunningOnAppServer (DWORD, Value: 1) to both:
KEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office Server\15\LauncherSettings
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office Server\15\LoadBalancerSettings
http://support.microsoft.com/kb/2910363/en