Philips 48PFK6409 - no standby LED - fell asleep by itself - revived with on-device "ON" switch

This must have been the weirdest case I ever had. I did not bother publishing it first. But after I was able to help with another case about a completely different Philips model (42PFL6008K) in the Repdata Forum, I thought I'd share my experience as it seems not to be such a rare problem after

all.

The symptoms are:

• Device suddenly stops working and would not switch on via the remote.
• Unplugging does not help.
• The standby light will not light up when plugged in.

The solution is: RTFM! I opened the device, measured all the way through it and found nothing. However, in the schematic of the power supply there was this ominous "ON" switch. I could not find any switches on that bugger. So I consulted the user manual.

And here is what you need to know:

So, are the users too stupid? Of course not. The TV obviously switches itself to a state as if the user pressed the button on the device himself, which he never did! The chain of cause and effect is not understandable and the user is left clueless, suspecting a defect.

We all have experience with device buttons, which are mirroring the function of remote control buttons. The on/off button on the device would do the same as on the remote. Not the case in those Philips models! The TV can be switched off to consume a minimum of energy. So it has three states:

"low energy sleep" <--> press button on device <--> "standby" <--> press remote on/off <--> "running"

Unconventional power supply architecture

The power supply did not have a dedicated stand-by circuit. Instead, the 12V output is throttled down to 6.3V in stand-by and some downstream regulators took care of the rest.