Z‑Axis V21404023 is a 13″–14″ monochrome CRT monitor used in industrial control panels. Common failure modes for this model include failed power‑rail transformers, cracked or burnt mainboard components (especially the video driver ICs), and degraded CRT phosphor or tube vacuum leaks that cause flicker or complete loss of image. First‑check diagnostics: verify 12 V/24 V supply rails with a multimeter, inspect the main board for burn marks or loose solder joints, and review any error codes or diagnostic LEDs on the front panel. If power is stable but the display remains blank, test the CRT tube voltage and backlight circuitry; if those are functional, replace the mainboard or video driver as needed.[oss-gpt-20b]