Panasonic TX-P42U30B how to locate thermal fuse

[Battle1066]

Hi all - Currently my problem is with a Panasonic Plasma TV
MODEL :- TX-P42U30B
Power board :MPF6909
Fault:- TV doesn't respond to its remote or built in set buttons, it just has the red display light stating standby. It has no flashing error code lights it just has a relay click from the power board intermittently.
What I would like help with is the best way to test the power board and the value of voltages at test locations, along with if it has one the transformer thermal fuse.
So if you can offer help please do.

[petehall347]

Re: Panasonic TX-P42U30B how to locate thermal fuse

standby light is key here .

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

standby light is key here .

Thank you for your reply.

Could you expand on that please, as I've limited knowledge in this area.

[tom66]

Re: Panasonic TX-P42U30B how to locate thermal fuse

No thermal fuse in this model as far as I'm aware.

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

No thermal fuse in this model as far as I'm aware.

Why I thought thermal fuse was:-
Off a PDF I found on this site for that sets service instruction - (hopefully I've attached this image it correctly) it states temperature sensor which I assume is a thermal fuse but may not be on the power board as I can't find the power board drawing.

[tw2005]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Why I thought thermal fuse was:-
Off a PDF I found on this site for that sets service instruction - (hopefully I've attached this image it correctly) it states thermal fuse but may not be on the power board as I can't find the power board drawing.

Solid standby, no response.

Have you checked if the SN is shorted?

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Solid standby, no response.

Have you checked if the SN is shorted?

Thank you for your post. I don't understand the (SN short form) but have attached an image if you mean the PCB on the lefthand side, then yes disconnected and no short.

[tw2005]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Thank you for your post. I don't understand the (SN short form) but have attached an image if you mean the PCB on the lefthand side, then yes disconnected and no short.

yeah that's it. Sometimes that can cause unusual faults. Not a common one then.

If I was to guess I'd lean towards faulty mainboard

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

yeah that's it. Sometimes that can cause unusual faults. Not a common one then.

If I was to guess I'd lean towards faulty mainboard

Always open to a good guess.

I would of liked to locate a power board drawing with test voltages or a guide to which areas to check this power and typical values
The service manual is very skimpy in it's advice for no power fault finding or fuse location.

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Always open to a good guess.

I would of liked to locate a power board drawing with test voltages or a guide to which areas to check this power and typical values
The service manual is very skimpy in it's advice for no power fault finding or fuse location.

Here's the service manuals advice for no power

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Tried a known working power board and still the same fault as above - anyone offer advice on which way to proceed please?

[Moreno83]

Re: Panasonic TX-P42U30B how to locate thermal fuse

The powersupply is not the problem.

You disconnected the left board completely right? ( SC20 + power cable ). If you only got a standby led with a clicking powersupply then you got a bad mainboard.

These models have problems with the mainboard. The solder under the CPU is bad , i have had a few of these.

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Evening - thank you for your reply.
I assume you mean board TNPH0954 - the board with the on of switch?

[Moreno83]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Yes indeed!

That is the mainboard , the cpu is under the thin heatshield.

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

Yes indeed!

That is the mainboard , the cpu is under the thin heatshield.

Once again your assistance is appreciated - is that a DIY repair or better as a replacement board in your opinion?

[budwich]

Re: Panasonic TX-P42U30B how to locate thermal fuse

I think you need to redo some of your testing AND also positively answer questions posed to you so that the forum is not left guessing.

First, how are you starting the set? You need to depress and hold the power button for more than 5 seconds and watch the response from the power led for flashing.

Next as suggested, disconnect the power cable going from the power board to the SC board ( two wire connector). You can measure the resistance of the sc board across those two pins. With the board disconnected, again depress the power button and hold for 5 seconds and release, what happens with the led?

the guide in this thread might help further
https://www.badcaps.net/forum/showth...roubleshooting

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

I think you need to redo some of your testing AND also positively answer questions posed to you so that the forum is not left guessing.

First, how are you starting the set? You need to depress and hold the power button for more than 5 seconds and watch the response from the power led for flashing.

Next as suggested, disconnect the power cable going from the power board to the SC board ( two wire connector). You can measure the resistance of the sc board across those two pins. With the board disconnected, again depress the power button and hold for 5 seconds and release, what happens with the led?

the guide in this thread might help further
https://www.badcaps.net/forum/showth...roubleshooting

Thank you for your input, I will read the guide but to answer your other questions.

I have at no stage held the power on button for five seconds so will do.

I disconnected the SC board and checked it for a short circuit with a multimeter it showed a resistance value.

When the set power on button is pressed the display shows a steady illuminated red light.
Now if I use the remote and press the red button on it, the set red light flashes showing the remote is working, this then follows with a relay clicking on the power board and set set stays this way until switched off at the mains.

[budwich]

Re: Panasonic TX-P42U30B how to locate thermal fuse

like most things in and around electronics, the sequence of things are important especially with respects to "failure mode operations". The "force sequence" in one... there are others. Anyways, based on my limited experience, the suggested guide should help you thru if you follow it reasonably closely. From my experience, just pressing the power button will not get you there as the "normal turn on" sequencing is not sufficient.

[Battle1066]

Re: Panasonic TX-P42U30B how to locate thermal fuse

like most things in and around electronics, the sequence of things are important especially with respects to "failure mode operations". The "force sequence" in one... there are others. Anyways, based on my limited experience, the suggested guide should help you thru if you follow it reasonably closely. From my experience, just pressing the power button will not get you there as the "normal turn on" sequencing is not sufficient.

I've quickly read your guide and will enjoy studying it further in detail, as it's the most comprehensive information I've been privileged to received on my current problem.
Tomorrow I'll action the sections related to my set and see how I progress but your help has put a simile on my face and will report back my findings.

[budwich]

Re: Panasonic TX-P42U30B how to locate thermal fuse

I found this other thread which shows the "guide" that I actually used on a 2011 set since there are some differences (according to the guide) on how flashing codes are generated.
https://www.badcaps.net/forum/showth...ic+plasma+2011
I don't whether is true for all sets / time frames but it does indicate you need to do more to get the "thing" to "flash"... but having said that, there are also "paths" for no codes. My "refuse claimed" set had only a solid red but after following the guide was able to narrow the issue down based on subsequent disconnecting / powering up sequences to point to a bad sc card / components.