First generation screen, found on GQH44, GQI44, GQJ44 and GQK44-JB chassis (Jubeat to Jubeat Copious)25.5-inch LCD with cold cathode tube (fluorescent lamp) made by Sharp. Tends to become yellowish/brownish and is usually burnt from years of use.The model number of the LCD is slightly different between the first generation and Ripples and onwards, but only the OSD version is different.They are as follows: (first generation) LFM255XL-251B (after Ripples) LFM255XL-251PYou can find more information about your screen and chassis on corei7-4790k's blog (in japanese): [1]
With time, those screens will become yellow/brown and will start to look dimmer and dimmer. To avoid this, make sure your screen is getting good airflow from the two blower fans located in the top of your jubeat chassis (The two VERY LOUD ones).