Feb 27, 2013, 11:03 PM
Post #1 of 2
I'm getting a bit frustrated with this one. It's a multi format, dual voltage set that I picked up from a military guy because there was sound but no picture.
Hitachi L47X02PXW - No Image on Screen
My first thought was inverter, wrong. I found that a couple seconds after turning on, the 24V from the PSU to the inverter was draining off. That led me to think the PSU had bad caps. I tested all the capacitors on the DC side of the board and some were a bit slow to change resistance so I went ahead and replaced them all. No change.
I knew there was a short somewhere so I started pulling boards to see if I could get the backlight on. When I pulled the T-CON and gave it power, the backlight started working. I noticed a solder jump where a fuse used to be on the T-CON and replaced the entire T-CON board. Now I have sound and backlight but still no picture. I was getting +12V and +3.5V on the new T-CON so I thought maybe the signal wasn't getting through from the main board (I don't have an o-scope).
After replacing the main board with what is likely to be the only one in spare parts inventory worldwide, no change. Today I pulled the steel surround from the panel to see if the ribbons were messed up or any of the SMCs were fried. Nothing is wrong there.
The screen is backlit but the panel stays blank (black). I have audio.
Does anyone have any idea what it could be?
TV repair hobbyist, former robotics technician by trade.