Nakhonchai Air (NCA) is one of big size operators in Thailand, and provide passenger bus services mainly to the northern and north-eastern regions of Thailand.
From Pattaya, they have route to such as;
Their bus terminal in Pattaya is located at Sukhumvit Road for Rayong, close to three way intersection of Sukhumvit Road and Pattaya Klan (Central) Road. Sukhumvit Road for Rayong means that the terminal is opposite side of Pattaya central area.
At the beggining of 2017, the three way intersection of Sukhumvit Road and Pattaya Klan (Central) is still under construction, so you have to go by a roundabout route to reach the terminal.
Web site of Nakhonchai Air