Philips 46PFL8007 - QFU1.1E LA - no standby LED - main processor dead

This is a short story with no happy end. I bought this Philips as defect and didn't ask any questions. The description said it wouldn't switch on anymore. Well, that did not sound so bad. I had fixed another QFU1.1 this year with a dead standby supply.

At pickup the seller told me that the TV had been fixed during warranty with the same symptoms. The main board was the culprit then. Uh oh...

When I plugged it in, the standby LED did not light up. Standby voltage was present. The LED is controlled by the main processor (the standby processor section). The only voltage the stdby proc. takes in is the 3.3V standby. Nothing else. The LEDs are fed with the same voltage.

I studied the service manual thoroughly and the only conclusion was that the processor was in trouble. I ran a reflow session in the oven as a last resort. Did not help. It is actually dead!

So, if you get your hands on a QFU1.1 chassis device with no standby light, there are chances that the main board is hopelessly broken. They are very hard to find, so don't bother!

Update


In the Iwenzo repair forum I got the hint to reprogram the standby software flash ROM. For that you need two things:

  • The software binary for the QFU1.1 platform. I found it in a russian forum. It is not available from Philips.
  • An EEPROM programmer. I ordered one from AliExpress. This will take a couple of weeks.

Also, I am going to investigate how an UART-USB adapter can be used to read the boot log. This will be interesting.

Update 2


My adventures with the UART adapters you can read HERE. This TV did not produce any log whatsoever. The CPU was not running any boot program.

In the meantime, I have received an EPROM programming device called SkyPro USB Programmer. It is made by Coright. The software installed flawlessly on Win10. I had to desolder the Flash ROM 7CT3 and solder it on an adapter board, which then went into the programmer's socket.

I tried a test clip from Aliexpress first directly on the board. This was like lottery. The clip did not attach properly and I got only nonsense results.

The software then identified the Flash as 25P10 (128k) instead of a 25MP05 (64k), which is listed in the service manual.

Reading the chip went fine. After erasing it, writing went well, too. I found the QFU chassis boot software in a russian form (sorry, forgot the link).

Well, unfortunately this did not help either. Absolutely no sign of life from the TV.