Hi there, first time poster here. I thought I would try my hand at TV repair, so i bought a broken hitachi unit. It has a vestel 17PW20v2 in it, and this is a horrible thing isn't it!
When I first got it, the standby light just flashed at me. After replacing a few caps, I managed to get the thing switching on, but it only switched on half the time, and I had this issue where the screen would freeze and very quickly fade away when asked to be too bright. About a half second after the failure, it begins to work normally. I replaced the board with one from ebay, and the unit now switches on consistently, but this issue still remains.
The symptom is that on these heavy white loads, a 3.3V rail on the PSU collapses. The backlight stays on, but all the pixels on the screen stop changing, and quickly begin to fade to black, from the outer edges of the screen inward. About a half second afterwards, the screen returns to normal. I have tried a number of different video and image tests, and it seems as simple as more pixels on = more chance of failure.
Sometimes, a number of short sharp impulses, maybe 4 a second, can be heard coming from the speakers as it recovers from a rail collapse.
Do you think this is a mainboard fault, or could I have bought an equally faulty PSU? Anyone got any ideas? I haven't been able to find anyone else with similar issues, but perhaps I am searching the wrong keywords. Also, I am from the UK so this will be a PAL model.
I am relatively competent with a soldering iron, but my theory is quite basic - I'm a loudspeaker guy really, just testing the waters here...
Thanks for reading
griff
When I first got it, the standby light just flashed at me. After replacing a few caps, I managed to get the thing switching on, but it only switched on half the time, and I had this issue where the screen would freeze and very quickly fade away when asked to be too bright. About a half second after the failure, it begins to work normally. I replaced the board with one from ebay, and the unit now switches on consistently, but this issue still remains.
The symptom is that on these heavy white loads, a 3.3V rail on the PSU collapses. The backlight stays on, but all the pixels on the screen stop changing, and quickly begin to fade to black, from the outer edges of the screen inward. About a half second afterwards, the screen returns to normal. I have tried a number of different video and image tests, and it seems as simple as more pixels on = more chance of failure.
Sometimes, a number of short sharp impulses, maybe 4 a second, can be heard coming from the speakers as it recovers from a rail collapse.
Do you think this is a mainboard fault, or could I have bought an equally faulty PSU? Anyone got any ideas? I haven't been able to find anyone else with similar issues, but perhaps I am searching the wrong keywords. Also, I am from the UK so this will be a PAL model.
I am relatively competent with a soldering iron, but my theory is quite basic - I'm a loudspeaker guy really, just testing the waters here...
Thanks for reading
griff
) and loose the color.
Comment