Simplify the following text for a Grade 8 native English-speaking person.
Original: BÄ lohlÃ vek was chief conductor of the Prague Symphony Orchestra from 1977-1989 . He became principal conductor of the Czech Philharmonic Orchestra in 1990 for a short time .
Simplified: BÄ lohlÃ vek became chief conductor of the Czech Philharmonic in 1990 .