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.
Thank you very much for your help, in fact, you don't even have to install the new firmware, you simply have to boot from the stick, as described in your instructions, and then change the source to get it out of it's bootloop.
ReplyDeleteI have a philips 40PFL4707. It gets into the philips logo boot loop. If I wait for say 5 min with power plug off, the TV starts properly and it then run for even hours.. but if I turn it off and turn immediately turn on, it gets into the boot loop
ReplyDeleteThe first thing I do with Philips TVs is to check the error buffer and start it in service default mode (SDM). Sometimes the boot loop will not occur in SDM. Your case looks like an unstable standby voltage problem and the standby processor doesn't boot.
DeleteHallo Hermann, ich habe bei meinen Philips ein DPS130 verbaut. Es hat auch den Fehler das nicht mal die Standby Anzeige leuchtet.
ReplyDeleteLeider kann ich aber die benötigten Teile nicht finden. Kennst du vielleicht lieferbare Alternativen?
Servus, welche Teile meinst du genau? Hast du die Standby-Spannung gemessen? Klingt so als wenn das Stdby Netzteil ausgefallen ist. Wenn die vorhanden ist, liegt es am Mainboard.
DeleteHi Hermann, i have got the same problem on a philips 32pfk5300/12.
ReplyDeleteThe logo and alternating on and of backlight. I have tried your steps without succes. But i am not sure i have the correct software loaded on my usb, do you have a link? Greetings R Herman
Sorry, I don't have any sources for this device. It is much newer and I wouldn't even be sure whether it has the same kind of problem.
DeleteOk, thank you. Then i will have to replace the entire main board.
Delete