Panasonic TH-42PX8E only relay click, no blinking

[schokobanane]

Hi,

i got an Panasonic TH-42PX8E TV from a friend because its not working anymore, he told me that it already had a failure before, and he has given that device to an techican who only has replaced a fuse which worked for 2 months. (i could get no more specific information)

the TV has the following symptoms:
- i hear only one a triple relay click directly after power connection or powering off and on again via button
- the standby LED in the front lights red while on and does not blinking
- there is also no blinking LED on any Board
- the display does not power on and keeps dark
- no visibile Parts are burned
- based on my information about the blown fuse, i've replaced Q406, F401 and F402 but the problem still remains the same
- disconnecting the SC and/or SS Board does not change anything

can anybody help me with that?
Thank You

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

It is likely an A board issue.

If you disconnect connector D5 (A5 on A board) the screen might light up full white. Does this happen?

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

Hi Tom, thank your for your response. i could not find D5 or A5, but P6, P7 and P25 (see attachment)

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

It looks like they've combined the A and D board into one board. Since the unit makes no attempt to power up, the A/D board is almost certainly the fault, but you can check some other things to rule them out.

You will need a digital multimeter, do you have one?

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

ok. yes, i have a multimeter, what should i do?

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

Check the VSUS line, do you know where to test that?

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

i found vsus on the power board but im not sure on which point i could get it.

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

There should be a two-pin blue/white connector, one going to SC and one to SS... VSUS is measured on one of these pins (the other probe goes on the chassis as ground.)

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

i get only 0,8 - 0,9 Volt on both connectors (P2 and P11)
it looks like that the value slowly increases.

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

OK, when you plug the set in, do you hear just one click, or two rapid clicks from the relay?

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

i hear two rapid clicks.

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

OK, and if you leave the set on for about 30 seconds, do you hear one final click? If it does not give the final click the A board is probably the cause.

What the A board does is first turn on the power supply and checks all operation. If it passes, it turns it off after it completes a channel guide update (over the air) which takes about 25 seconds. If it fails (the P board test, not the guide update), it should click rapidly three times and then blink 10 times indicating 15V failure or 2 times indicating another type of 15V fault. However, it appears it is never reaching either of these states, which means it's getting stuck in the boot process.

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

i hear one final click, but after 60 Seconds.
the relay, sounds like "tickeltick" after power on, it could also be a 3 times click for another ear.

please, could we continue tommorow? unfortunately it's very late here, so i need to go sleep for now.
many thanks for your support.

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

i'm back again..

[tw2005]

Re: Panasonic TH-42PX8E only relay click, no blinking

Hi, I know Tom is running with this one but in post 2 I believe he was trying to get panel on without the a-board.

Also with Q406, F401 and F402 , did you replace these because they were all faulty/blown?

If so, check R411, 10ohm 5W ceramic resistor, tall large white one nears those fuses, maybe open cct.

I found this for 11th gen plasma.

"The result obtained on previous generations when D3 was disconnected, can now be obtained by disconnecting A6/P6 and A7/P7.
When these connectors are removed, the A, K, GH, and S boards are disabled.
Normally Pin 2 of connector A3 is grounded by Q4014-Q4015. When A6 and A7 are disconnected pin 2 is no longer grounded. This allows for the 3.3V regulator on the D board to output 3.3V to the Panel CPU (IC9003).
The Panel CPU (IC9003) outputs a command that is provided to 2 different circuits.
The “Panel Main On” command (3.2V) is connected to pin 11 of connector P25 on the power supply turning on the circuit that generates Vsus, Vda, P15V, and P5V.
The “Power On/Off” command (3.2) is connected to the Video/Panel Control and Discharge circuit to output the panel drive control pulses.
This method of isolation is useful when troubleshooting problems where the A, GH, K, or S board are suspected to be defective."

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

Hi tw2005, thanks for your support, should we continue with getting the panel runnig without the a-board?
I think Q406 wasn't the reason, the fuses wasn't blown and the symptoms are the same like before.
R411 seems ok, i got resistence from it.

[tw2005]

Re: Panasonic TH-42PX8E only relay click, no blinking

You could try disconnecting those 2 connectors and see what it does. I've never tried it before although I have done something similar on a 2005 model and the SC and SS boards turned and that proved i had a bad DG board on that one.

Tom's going to have more experience in this area and he's online.

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

ok, nothing happens if i disconnect these 2 connectors. i hope for Toms suggestions now..
Thank you anyway.

[tom66]

Re: Panasonic TH-42PX8E only relay click, no blinking

You do not see any panel glow or LED on SC/SS?
What about Vsus does that hit ~200V?

[schokobanane]

Re: Panasonic TH-42PX8E only relay click, no blinking

Hi Tom, there is nothing to see on the SC and SS, also no display glimming. the only reaction are the relay clicks and the red standby LED without blinking. if i disconnect P6 from the A-Board i see the 10 times blinking of the standby LED.
On the power board itself are two LEDs? in the near of the relay - for what are these? I've never seen them lighting, should they?
What did you mean with VSUS, i've measured it on the connectors P2 and also P11, but i'll get only 1 V. did i misunderstood something?