Viera 42 inch LCD,not firing up Looking for a bit of help ..

[ceedy]

our Panasonic TX-L-42S 10B 42 inch TV is not starting up ..

power LED seem to be flashing a 4 Blinks Code ..

Been told, but so far I've not been able to confirm , this refers to some Power supply problem ??

The PSU is a TNP 8EP 101.

I've had a peer inside for starters and the Whole PSU is visibly very clean with no Bulging Caps ?.

Can Anyone give any help

heres hoping ...

Happy Christmas one and all

Chris

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

4 blinks does usually indicate a power board issue.

Clue us in on what you have... a camera to take pictures is essential, and a digital multimeter is necessary for almost all testing.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

hmm wot I got ???

A brain that mostly Still Works

Fluke meter, Weller iron , a decent Digi camera and A fair bit of Electonics kit and Capability, but a bit out of practice in fault Diagnosis, and especially in TV's & Psu's .

But able to follow any guidelines..

Typically I think whenever we ever have had any TV probs its always at Christmas ??

Did a couple odd smaller LCD PSU's ( 1 Caps/trans, 1 whole power board ) last year for the kids and they are still going!!


Chris

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Can you take some pictures of the boards inside your TV? And one of the general layout?

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Piccy of the PSU for starters..




C.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

The other Board ..





And Overall Piccy .




Hope they are good enough ?



C.

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Can you test the voltage on those pins on the power connector going to the AV board (with the video inputs) from the power supply board (where mains power plugs in.) Test with positive lead on each pin, negative lead on chassis.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Can you test the voltage on those pins on the power connector going to the AV board (with the video inputs) from the power supply board (where mains power plugs in.) Test with positive lead on each pin, negative lead on chassis.

Ok.. theres 23 connections .
starting at the top ..
Pins
1= 0v
2=0v
3=5.26v
4=0v
5=0v
6=0v
7=0v
8=0.56v
9=0.56v
10 to 19 all = 0v
20=5.76v
21=0v
22=5.76v
23=5.76v
......
Chris

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

OK; I forgot to ask, was this in standby or powered on (attempting to power on possibly with blinking LED.) If you press the main power button on the TV, do these readings change? I can't find a service manual for this model, so I'm trying to identify possible output and control voltages.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

OK; I forgot to ask, was this in standby or powered on (attempting to power on possibly with blinking LED.) If you press the main power button on the TV, do these readings change? I can't find a service manual for this model, so I'm trying to identify possible output and control voltages.

This was in Powered on mode .. with blinking LED 4X

But the levels are the same when Off too.

All I get when pressing the power on switch is a relay click a moment of Power led Flashing green and then the 4x blinking.

I've not managed to find a wiring Diag yet either .

C.

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Ah, I didn't notice there's a rigid flex connector going between the PSU and main board.

Do you see any other voltage changes on here when power is on/off?

It is definitely pointing to POWER SOS (4 blinks.) What is the part # for the PSU? Will be like "TNPAxxxx"

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Ah, I didn't notice there's a rigid flex connector going between the PSU and main board.

Do you see any other voltage changes on here when power is on/off?

It is definitely pointing to POWER SOS (4 blinks.) What is the part # for the PSU? Will be like "TNPAxxxx"

The PSU is a TNP 8EP 101. ( in the 1st post )

only found 1 place that can supply one of these at the moment but didn't want to jump in and buy one ( as its not cheap )
just in case its something else ?

I did the volts checks on the 23 way rigid /flexi's

Going to hit the hay now .. as the Light is a bit poor ( along with the eyesight this time of the evening) so will re run over the voltages in the morning .. but fairly sure there were no other variations on the 23 Rigid/flexi links) when switching on and off.

C.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

back again,

No changes to any voltages when switching on and off..

The sequence is . Press power button, Relay clicks , LED Flickers green
for a few seconds then the relay clicks off ? and the 4x Red blinks start ..

chris



PS Found this ??? just a few bits of info maybe ?

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

I'm trying to find a service manual for this to see what the pin out is supposed to be.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Found a bit slightly different PSU info .. a TNp8EP103 .. the error codes for
this says the 4 x blinking is " sub12v_sense_SOS "

C.

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Can you check the diodes on the output of the PSU transformer for shorts?

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Can you check the diodes on the output of the PSU transformer for shorts?

Which exact ones do you mean ?

All the diodes on the board seem ok except the component D801 ? bottom right of the PCB , right next to, and seemingly across the 250v input ?

this is open circuit both directions ..

Chris.

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

The diodes on the heatsink.

The "diode" across the mains should test open, it is a TVS; a surge suppressor.

[ceedy]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

The diodes on the heatsink.

The "diode" across the mains should test open, it is a TVS; a surge suppressor.

OOps .. missed those..

Just took the board off to get at them

they are all En220a

D835 reads different to the other 2 , centre pin to outside ones on this are open circuit

the other diodes read 300 ohms ish.

[tom66]

Re: Viera 42 inch LCD,not firing up Looking for a bit of help ..

Can you use diode test?

Open diode is rare, most common is shorted.