I used to have an old Sony camcorder (MiniDV) that I used for several years and accumulated about 20 tapes worth of video footage.

The memory backup battery decided to go into meltdown one day and it destroyed the camera.

A few months ago I decided to transfer all of the old tapes onto PC so I bought a second hand Canon to play the tapes on. None of the tapes will play correctly (they have digital noise/mosaicing on the in-built screen).

I assumed (probably incorrectly) that MiniDV was a standard and all camcorders were equal.

Mini DV is indeed a standard so you tapes should play, however if the head alignment on one of the cameras wasn’t set up correctly then you’ll only be able to replay tapes that were recorded on that device originally.
Another possibility might be that the original recording was done at half speed and the new camera can’t do that.

It is a standard, but Sony being Sony used a ‘version’ of it IIRC.

Ah, yes, here.

https://en.wikipedia.org/wiki/DV

See the entry on “DVCAM”. Seems it’s something targetted at the Pro market, so may be a red herring. In which case, I’d go with what Rockhopper said, heads might be out of alignment on one of the two, or need cleaning.

What does new footage shot on the camera look like?

Thanks for the replies. New footage on the Canon looks crisp. I guess I will have to have a look around for a second hand Sony MiniDV

Where abouts are you? I have a JVC miniDV camera you could try.

As above, I’ve got a Sony DV lying around.

Not been fired up in years though….

I’m in Bristol, either of you two close by? Thanks for the offers.

Derby 🙁