HITACHI - PLASMA TV _ NO PICTURE _ TROUBLESHOOTING _ MODELS _P42H401, P42H4011, P50H401, P50H4011, P55H4011, P55H401, P42T501, P50S601, P50V701, P50X901, P50T501, P55H401, P55T501 and P60X901 - [1]

                                                                        [1]

NO PICTURE

Probable Causes

1. The Power Supply may not be producing the correct voltages.
2. The Digital Module (Digi-Main) may not be producing correct turn on commands (Power 1 and 2).
3. The Logic PWB may not be supplying the correct Vs/Va turn on commands (Vsago and Vcego).

The Panel can have a defect of:

• The panel is shorted.
• The panel is defective, but not presenting a short.
• Y-SUS and/or X-SUS may be defective (Shorted and or nonworking).

Monitor the front Power LED first:

• Does it turn on, then go completely off? (Indicates Shutdown), Power Supply not running. (Shutdown usually indicates a Short.)
• Does it turn on and stay Green, but no picture. (No Shutdown),
• Power Supply running basic power supplies, but Vs/Va voltages not being produced.

Next open the unit by removing the back cover. Check the following carefully by visual observation.

BUFFERS (Drivers) ON SDR Upper and/or Lower PWBs (50”~60”)

     Take a moment to carefully observe the Buffer “Snot” Chips (Left Side black chips mounted on the SDR Upper and Lower PWBs).  Look very closely for burns and/or small holes in these chips.  If any defect is seen, the PWB is defective. Replace this PWB and the Y-SUS if PWB not upgraded. Replace only SDR if PWB is upgraded.

• COF (Chip on Film) from Panel to A-BUS (42”)

• Look very closely for burns and/or small holes in these chips.
• Look very closely for any ribbon cable damage on the connections to the Panel itself from the A-BUS PWBs.
• If any defect is seen, the Panel is defective.
• Some additional disassembly is required to see these COFs as they are on the underside of the ribbon cable coming from the panel to the A-BUS L, R and C PWBs.