FAULT: NO PICTURE
Reasons
- The power supply may not be producing the correct voltages.
- The Digital Module may not be producing correct Turn-On command s [Power-1 & Power-2]
- The Logic PWB may not be supplying the correct Vs/Va Turn-On commands.
- The Panel shorted.
- The panel is defective, but not presenting short.
- Y-SUS and or X-SUS may be defective. [Shorted or non-working]
Monitor the front panel Power LED.
- Does it turn ON, and then go OFF completely (Indicates shut-down). Power supply is not running. (Might be due to a short circuit).
- Does it Turn On and stay Green, but No picture. No shut-down.
- power supply running basic power supplies, but Vs/Va voltages are not present.
Observations [Power supply]
- Look carefully around all mounting screws for cracks or PWB damage.
- BUFFERS (Drivers) on SDR Upper and/or lower PWBs [50" to 60"]
Carefully observe the Buffer "Snot" Chips. Left side black chips mounted on the SDR upper and lower PWBs. Check very closely for burns and/or small holes in these chips. If any defect is noted, make sure that the PWB is defective. Replace it and the Y-SUS if PWB is not upgraded. Replace only SDR if PWB id upgraded.
COF [Chip On Film] from panel to A-Bus [42"] Carefully observe the COFs (mounted on the flexible ribbon cables). Look very closely for burns and/or small holes in these chips.
Check whether any ribbon cable damage on the connections to the Panel itself from the A-BUS PWBs. If any defect noted, the panel is defective. Some additional dis-assembly is required to see thes COFs as they are on the under side of the ribbon cable coming from the panel to A-BUS L, R and C PWBs.
Contd: