I get a protected message up when trying to record -regardless whether the tab is in or out ?

The switch is right where the protection tab is on the cassette when the tape is inserted. It is unlikely you can fix, and as it is a quality recorder, I would take it to a Sony Service Centre.

https://www.google.com/search?q=Sony+hi8+CCD-TRV138+record+protection

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There are only two possibilities - there IS something wrong with your write-protect tab (try opening and closing it once), or there is something wrong with the little arm that reads the tab (perhaps it got bent).

What happens if you use a different disc?

Try the Users Manual http://www.minidisc.org/part_Sharp_MD-MT15+MT16+MT20.html (or whatever model you have).

Google sharp MD-MT280E and download the Users Manual.

You have unheard messages on the voicemail system provided by your telephone company. This system records messages when people call while you're already on the phone. Please contact your telephone company for instructions on accessing their voicemail system.

You have unheard messages on the voicemail system provided by your telephone company. This system records messages when people call while you're already on the phone. Please contact your telephone company for instructions on accessing their voicemail system.

On the mini-DV tapes I have, the protect tab is a slider- it does not come out of the cassette. If you look at the back edge of the tape, where the long label goes, the protect tab is at the right hand end. When it is set to prevent recording it will look like a little square hole, but there should be a tiny edge of the tab showing (mine is green) which you can pull across with a fingernail or sharp object to cover the hole and allow recording.

Yes,
In the Disc Management options you should have the option to change whether disc protection is on or off.

Also, if you have one of the double-sided discs - they look like large computer floppy discs and can be inserted either way up into the machine - some of these have a "write protect" tab just like a floppy disc. Check to see if yours has one and whether it is set in the protect position.

Don't know your machine, but is it possible that it's seeing your source tape as write protected (missing tab) and so assuming it should not be copied to the DVD?

A picture of protection tab in protection position