Criminal Records, Expungement Juvenile expunged record visible to judge?

[BarbOurYear]

Just a quick question ... Is it true that a juvenile's expunged record would be visible to the judge when the defendant goes to court as an adult? If so, would info on his past record, though expunged, have any impact on a new misdemeanor sentence? This pertains to CA.
As always, thank you for your time.