The first thing to do is to start the emergency software installation. For that, you need an infrared remote, which does not come with the TV. You can get one for around 10€. The reason being that the software, which manages the original radio remote control will not be loaded under such circumstances. Silly Philips!
- Disconnect the TV from the mains
- Press OK or DOWN on the remote and hold it
- Plug in the mains.
I did that and the recovery program came up. Good! This means that the screen, the backlight, and the main processor are doing fine. It can only be a problem with the software or the devices that store it, respectively.
The QFU main software, which I downloaded from Philips, installed fine. The TV went to standby - and did still not start.
Next up: logfile reading. I plugged in my adapter (see this post) and realized that the device is looping. It did not stop randomly while booting, rather it happened at more or less the same moment. The last log message was truncated, no indication that the loop was intended by the software.
This means that the processor always crashed for the same reason. Processors crash due to corrupted software. As I had installed the software previously, I came to the conclusion that the NVRAM chip must be faulty.
In the schematics, the chip is a MT29F8G08ABACAWP. In reality though, it is a MT29F8G08ABABAWP.
It is a 8GB NAND chip.
I was able to to find the binary image of the software. Now I needed a programmer with which to load the software onto the chip, and a supplier from where to buy it.
I got the chips from Aliexpress HERE. It worked fine.
The programmer I chose was THIS MODEL. It also worked flawlessly.
In case you search for programmes yourself, make sure the exact name of the chip is on the compatibility list. The letter soup is confusing and I got it wrong once and bought a non-suitable programmer first.
Swapping the chip was surprisingly easy with my preheater plate and a large nozzle on the hot air gun. In about 15 seconds the chip already floated.
With a new programmed chip soldered in (use lots of flux and a good magnifier glass!) the TV behaved differently. I was able to start it with the remote and everything seemed fine. However I was not successful each time from standby. It would not listen to the remote everytime.
So I checked the log again and spotted yet another form of boot loop, this time initiated by the software in a consistent and regular manner. The crash was gone, but the TV would refuse to go to standby properly. Instead it first attempts to stop, ambilight goes off, standby LED switches off - and then it reboots into some semi-standby. This repeats forever.
The standby LED actually has three states, which it goes through:
- Dimmed. The TV is not listening. Any command from the remote gives me a quick flickering.
- Off. The TV is not listening. Any command from the remote gives a slow, bright blinking.
- On. The TV will only start in this state.
...repeat from top
A reinstall of the software did not change anything. I also read the boot EEPROM and it was 100% identical to the binary that I have on disc.
I have no idea what to try to fix the loop. The hardware is working. WiFi, ambilight, radio remote, all good.
My only guess is that there needs to be some extra software on the NVRAM chip. Yet, the binary image I got from the Russians was a dump of the chip. I am not even sure anymore whether it is necessary to burn the software onto the chip, because the emergency recovery software will program it, anyway.
So here I am. A TV which is basically working fine, but won't switch itself off to standby. At least I have learned yet another QFU fix, sort of.
Update
I soldered in another NAND with the working software from a 55PFL6158 and now the thing does not even write a log anymore. The CPU gets a little warm and then cools off. This cannot have anything to do with the NAND. It is not even trying to boot. The SPI is good, too.
I tried a reflow of the CPU with no luck.
As it turns out, there is a short on one of the power supply lines for the Fusion processor. This CPU needs a reball and if that's not helping, it is probably toast.
