Flying back from Parys yesterday, the RPM indicator on my Skydat DX2, just went blank, while all other information were still displaying fine i.e. Alti, Speed, etc.

What is funny is that my electronic compass, seperate instrument, also went dead i.e. looks like no power.
Now I haven's started fualt finding yet, but hope someone can give some tips before I start, that might have had similiar RPM problems before.
Thanks in advance.
Regards
Rudi