panasonic TX-P42S20E plasma tv difficult to turn on

[anno]

hi

i have a panasonic plasma tv. model tx-p42S20E. it is hard to turn on, eventually it is turning on. sometimes first try , sometimes 20 tries.

the power led is flickering green , then it goes to red again. 1 sec on , 3 seconds off. i have service manual and it says it's an unknown fault.
i tried to disconnect the power cables to the x and Y board but same symptom.

can anybody help me? thanks

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

i measure voltage on big 450v cap and voltage is low 270v

[tom66]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

Does 450V cap voltage hit 390V when it does turn on? What does it do as it fails to power up? What do Vs and Vda measure when this occurs?

[tw2005]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

Sounding like SOS1 - A board replacement

Can't tell you much more, being intermittent hard to know whether it's the processor or something simple like a bad cap on the board.

I have had SOS1 due to bad flash chip but that was permanent 1 blink.

Generally you'll need an A board. Not too many A board repairs seen for this but it's something that would be nice to nail in case it was something simple.

Could try warming the board and see if it turns on easier but not that will prove a lot.

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

it doesn`t want to start atm. the vsus voltage is 205v and the vda is 60v.
maybe here is a PFC problem because the low voltage on the big cap?

[tw2005]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

it doesn`t want to start atm. the vsus voltage is 205v and the vda is 60v.
maybe here is a PFC problem because the low voltage on the big cap?

I don't see how with those voltages which are normal.

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

ok. is it possible to test the power supply standalone?
with resistors on some 'on'' pins ?
can i take a 230v lightbulb for the vsus load?

i am not sure wich pins i have connect with each other
P& connector is labeled :

1. STBY5V
2. GND
3. S0
4. S1
5. F_STBY_ON
6. ECO-ON
7. Panel_main_on
8. STBY5v_on
9. SOS4_PS
10. AC_low
11. ALL_off
12. main_Sw_1
13 NC
14. Main_sw_2

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

i think i didn`t measure the voltage right. because i couldn`t reach the big cap i measured on the + - legs of the rectifier. but PFC is further down the line, if you know what i mean. So its probably error of the A-board? I checked pin 5 en 7 of connector 7. When starting up they are 3,3 volt both and when turning of they go to 0 volts. (F_stby_on and panel_main_on) . Is this because A-board is turning of the main power supply?

is it possible a voltage regulator on the mainboard is not working? i work on tv tommorow again

[tw2005]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

i think i didn`t measure the voltage right. because i couldn`t reach the big cap i measured on the + - legs of the rectifier. but PFC is further down the line, if you know what i mean. So its probably error of the A-board? I checked pin 5 en 7 of connector 7. When starting up they are 3,3 volt both and when turning of they go to 0 volts. (F_stby_on and panel_main_on) . Is this because A-board is turning of the main power supply?

is it possible a voltage regulator on the mainboard is not working? i work on tv tommorow again

NO. Not in my opinion. Do you have any manuals or guides? problems with sub voltages etc all have their own error blinks.

SOS1 - Panel information SOS, PD5 Start SOS

Search PD5 in the service manual PDF doc and you'll end up in the A board.

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

yes i have service manual.i have 1 sec blink 3 sec no blink . Error 1
it says unknown SOS . panel information SOS PD4 start SOS

i don't know what panel information SOS and PD4 start SOS means. But i think i'm going to find and replace the A board. thanks for help

[tw2005]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

yes i have service manual.i have 1 sec blink 3 sec no blink . Error 1
it says unknown SOS . panel information SOS PD4 start SOS

i don't know what panel information SOS and PD4 start SOS means. But i think i'm going to find and replace the A board. thanks for help

Sorry , looked at the S30, but same,same. PD4, panel SOS. I cleared a X20 which had SOS1 confirmed corrupted flash ic, but yours being intermittent hard to say.

Not a board many try to fix with the 1 blink, new A board should sort it if you can get one. make sure you get the correct revision as i suspect with that the same PCB may be used for both HD and FHD models and different sizes as well.

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

I changed the A-board and the tv is fine now. thanks

[KORHAN DEGIRMEN]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

I changed the A-board and the tv is fine now. thanks

Dear Anno;

How could you find A BOARD for TX-P42S20E? Could you please share with me?
I have some problem with A board too.

https://www.badcaps.net/forum/showthr...581#post444581

[anno]

Re: panasonic TX-P42S20E plasma tv difficult to turn on

sorry for the late reply, but i found in a webshop that sells used lcd/plasma parts
http://www.lcd-onderdelen.nl/a-37205...s/tnph0838-1a/

i am not sure thats the good one. someone told me to reflow bga chip on A board. i have not tried that