HITACHI PLASMA 42EDT41 CMP420V1 CMP420V2A Troubleshooting

Cont:
SYMPTOM:  Unit would power ON but with no picture.

• The unit did have sound.
• The front power LED ON.

Check the test point JP on the Y-Drive PWB Upper and Lower PWB.

• Normal should be  [ -16 with color bars with color turned OFF as input signal].  This varies due to picture content.
• This voltage is extremely high ( >85V) and doesn't fluctuate, except a defective Buffer on the underside of the Y-Drive Upper and Lower PWBs of a defective Y-Sustain PWB.
• Check the Outputs of Buffers on the Y-Drive PWB upper and lower PWB.  
• Normal should be 50.9V.  This voltage will vary due to picture content and flucuate 5V up or down.  
• If this voltage is extremely high and not fluctuating, except a defective Buffer on the under side of the Y-Drive Upper and Lower PWBs or 
• A defective Y-SUS PWB.
• A defective Buffer will make all output voltages test High and the JP test point High.
• Unplug the connectors one by one from the Y-Drive PWB to the panel.  If the voltage returns to normal then the buffer feeding this connector is bad.  There are 4 connectors for each Y-Drive PWB.  4 for Upper and 4 for Lower.
• If only have a defective buffer, when the right connector in unplugged, the other voltages will remain to normal [50.9V] and the picture will return , but only on the top of bottom half.
• In case only need to replace the Y-Drive PWB with the defective buffer.
• Y-Drive Upper PWB part number [TS05672]
• Y-Drive Lower PWB part number [TS05673]

SYMPTOM:  The unit would power ON but with no picture.

• The unit did have sound.
• The front power LED is ON.

If after all connectors to panel assembly from Y-Drive boards, the voltages still remain incorrect:-

• Remove the Y-Drive PWBs.  Look at the buffer underneath.  May find small burn marks on the buffer.  Any one of them either Upper or Lower Y-Drive PWB.  If the voltage check showed defective buffer or any one buffer is found to be burned, replace the following.
• Y-Sustain PWB.  Part number [TS05679].
• Y-Drive Upper PWB.  Part number [TS05672]
• Y-Drive Lower PWB.  Part number [TS05673]

Warning:  If a burned buffer is found, the Y-Sustain PWB must be replaced along with the Y-Drive PWB.  Failure to do so, could damage the new Y-drive PWB when installed.