STB3.3v = 0.4V on Panasonic p42v10

[Neelix]

Re: STB3.3v = 0.4V on Panasonic p42v10

The parts on the A board can be tiny and easy to loose. So be careful

[Neelix]

Re: STB3.3v = 0.4V on Panasonic p42v10

You're measuring 4.2 ohm between STB3.3V and GND which is far too low. One or more parts on the STB3.3V supply line is shorted and pulling the STB3.3V down. That's why you're only measuring 0.4V. You must find out which part. Start by removing L5480 from the A board and then measure the resistance between STB3.3V and GND again

[Neelix]

Re: STB3.3v = 0.4V on Panasonic p42v10

Service manual -

[rvanpruissen]

Re: STB3.3v = 0.4V on Panasonic p42v10

There's a regulator on the A-board (IC5480) which supplies the STB3.3V, based on the STB5V. I've included some pictures:

• 409: Overview
• 408: A-board component side
• 412: Close-up of IC5480
• 413: A-board foil side
• 414: Close-up of IC1100 which is should be powered by STB3.3V (among others

Meanwhile, I've found out that when I disconnect A3 connector (to D-board) and leave the rest plugged in, the TV powers up: relays click, backlight is on but still no standby light. At this point, STB3.3V becomes 0,67V (less load I suppose).

[Agent24]

Re: STB3.3v = 0.4V on Panasonic p42v10

Where does STB3.3v come from? PSU directly or derived from a secondary regulator on another board?

Can you put up some photos?

[rvanpruissen]

Hi guys,

Recently I've been given a faulty Panasonic p42v10. The symptoms are as follows:

• No response when on power
• No standby LED
• No relay clicks

After some research, I found out that:

• STB5V rail is measuring 4.5V (just within tolerance?)
• STB3.3V rail measures 0.4V.
• STB3.3V has a resistance to ground of 4.2ohm with no cables connected to the board (A-board).

At this point I'm not sure how to proceed as there are many components connected to the STB3.3V rail, all of which could be shorting to ground.

Any help is appreciated!

Cheers, Rick