How do you replace the alternator on a 1990 Volvo 240 DL?

To replace the alternator on a 1990 Volvo 240 DL, first disconnect the negative battery terminal to ensure safety. Remove the drive belt by loosening the tensioner, then detach the electrical connections from the alternator. Unbolt the alternator from its mounting bracket and take it out, then install the new alternator by reversing the process: secure it in place, reconnect the electrical terminals, and reattach the drive belt. Finally, reconnect the battery and check the operation of the new alternator.