Mintek dtv-265-d dvd broke
To fix this problem, the following assumes you have unplugged and taken the back off the TV, and removed the metal shield around the mainboard. Open the back carefully as there are a couple of ground straps that must be unscrewed before the back is completely freed. There are plenty of lethal voltages inside the TV, so do this all at your own risk.
I'm an electrical engineer and I just fixed a DTV-265-D that I got with the same problem. I'm not 100% sure what fixed it, but I located the problem and can hopefully inspire some other findings by others. All TV/DVD buttons, and remote control signals go into a small miicrocontroller (U75) on the bottom left corner of the mainboard. This button converts all buttons and remote signals into a decoded data signal with a 5V level (normally high).
Just above and to the right of U75 is a small 8-pin chip that appears to split and send the data signal to the DVD module and the TV microcontroller at two different voltages. Pin 1 of this chip is on the bottom right of U18 and the pins increment counterclockwise. The important signals I found were:
-Pin2: 5V Data input from U75 microcontroller.
-Pin3: 5V data signal sent out the red wire of the connector next to U18 going to the DVD player.
-Pin5: 3.3V data signal sent to the main TV microcontroller.
-The other pins may switch this signal back and forth somehow, but I have no way of telling without a schematic
I found on my unit that something was causing the signal not to get properly to the TV or DVD player. I resoldered U18 and things started working again. I'm not 100% sure this is the final fix, but U18 IS THE ULTIMATE CAUSE OF THE PROBLEM. Neither buttons nor remote signals are ever getting to the DVD module or the TV. Once I resoldered, both signals on pin 3 and 5 were clean and everything worked again. U18 may need to be removed and replaced with a simple voltage divider to get the proper voltages to the proper modules, but I haven't tried to go there yet.
A way to test if this is your problem is to remove the red wire from the harness next to U18 (the harness going to the DVD player). Somehow connect this wire to pin 2 of U18 (there's a convenient test point nearby), reconnect power, buttons, etc. and CAREFULLY test. Now, ALL the buttons for DVD control will work again but not the buttons on the TV side will work. You should be able to eject the DVDs and this may have unlocked this weird state. You would have to restore the red wire back to it's original position to have proper normal operation.
I used (and would highly recommend using) an oscilloscope to fix and debug this. There are plenty of lethal voltages inside the TV, so do this at your own risk and only if you at least kind of know what you're doing with electronics. So far it's been a week and everything is still working fine.
Jan 05, 2008 |
Mintek LCD TV Progressive Scan DVD Player