Hello, I have a problem with my backlight, I dont know if the trouble is in CCFL or on the mainboard, I tested voltage output, but my multimetr doesnt support voltage over 750V~. Is it possible that all 4 CCFLs crashed together? I have no idea how to test if the CCFLs are ok

Please clarify actual symptom,No Display is normally due to failure of Invertor transistors and related fuse.CCFL normally do not fail in 2-3 years.