In the installation folder of your Studio, where the executable you are using is located, edit the ini file that has the same name as your executable. For example, if you are starting Studio with Talend-Studio-win-x86_64.exe, edit Talend-Studio-win-x86_64.ini.
Make sure other instances of the key wrapper.java.command are commented out by having a # at the start of the line.
Open Regedit, and under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\talend-rjs-6.2.1, edit the key ImagePath to replace the first argument with your desired java.exepath.
Find the name of the TAC service: in the Windows Services interface, double-click the Talend Administration Center service to open its configuration, and note the Service name shown in the General tab.
Open a command prompt as an administrator.
Navigate to the tac > apache-tomcat > bin folder, for example C:\Talend\6.2.1\tac\apache-tomcat\bin.
Run the following command, using the service name you found earlier, in this case talend-tac-6.2.1:
This opens a configuration GUI.
In the Java tab, modify the Java Virtual Machine to point it to your desired installation - it must point to the jvm.dll in the server folder.