I opened the cover and the first thing I noticed where a number of dead flies! The device came from a farm village in the countryside and those suckers like it warm :-)
The voltages from the power supply were ok and stable. The only instability I measured there was the BOOST line, which controls the backlight intensity. It went high and low in a loop. That was the reason for the backlight flashing.
So I focused on the main board. All major voltages ok and stable, except the V-LNB (satellite supply), which switched from 11.6V to 19.4V and back. This is intentional during boot and described in detail in the service manual. I also noticed that the audio amplifier chip got muted and unmuted in regular intervals. Both things are controlled by the main processor.
I did not assume that the processor itself was dead, because it did run a program, obviously. A flash ROM maybe? RAM? It very much looked like a software or device configuration problem. Those kind of bugs can sometimes be fixed by reinstalling the firmware.
After an intense study of the service manual I found a technique to update the software blindly:
- Switch off the device with the mains switch.
- Insert a USB stick with the software.
- Press OK on the remote and keep it pressed.
- Switch device back on. Wait for instructions.
I did that and the TV came back alive. Hallo Frau Johansson!
I've always liked the upper range Philips from 2009-2011 and this one is no exception. How it got hung up by itself is a mystery.
