Sansui SMX4019SM User Manual page 17

Choose the Lock system option with the up and down keys
down. Then, open the lock function with the left and right.
Remember that the initial password is 0000.
If you want to adjust the password, you must first select the
option of set the password and then enter the previous
password and the new password.
When you enter the new password again, you make sure
that confirm the previous one, this means that you have reset
the password correctly.
When you want to protect some programs that you do not
like, select the option to block program and enter the number
of channel.
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