Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

[LDSisHere]

I have Panasonic TH-46PZ80U plasma TV that I would like to get working again and I am hoping that some of this forum's members would help guide me in figuring out why it is not

I was told that the TV was on during a storm; it went out during this storm and would not turn on for ~24 hours. When it would turn on again, all you could get to display were the menus. It was then placed into storage a little over a year ago.

I was able to find the service manual for this model. I have used it, as best I could, to troubleshoot this TV but it has not helped very much. I have tried searching for relevant information in this forum and Google but I could not find very much helpful information, for this problem at least. I can read schematics and use a millimeter but have zero TV repair experience and I have discovered that a plasma TV is very different from a computer monitor.

The following list is what I have tested and some of my observations:

The TV will power on and the power LED stays on solid like it is supposed to do. (No flashing)

The TV displays the basic setup menu. The entire menu system seems to work fine and it displays just as it should.

It will pass the built in self-test for processors, ram, etc.

When powered on, the SC and SS boards both have green LEDs lit like the manual says it should.

The SD card slot will display thumbnails. I do not have the factory remote so I have not been able to get it to try a slide show, but I suspect that it would work.

When trying to use the cable input, RCA jacks(1-2 ), or HDMI(1-3) inputs there is no picture, no snow and no sound. It displays a message something to the effect of “no signal detected”. I have not been able to test the s-video or the component video.

Resetting it to factory settings did nothing but show the option to set it up for a hotel when it was restarted.

With so much working and it passing the self-test I am thinking my problem is somewhere on what the manual refers to as the “A” board around the audio video SW chip. Of course, I have no experience in TV's so I could just as easily be looking at the incorrect board and not know it. I am going to attach pictures of this board that I have taken already. If other pictures are needed, I will take images of what is required, I just do not want to remove anything unnecessarily. If anyone wants the service manual, I will send it or send a link upon request. I did not know if it was appropriate to upload it directly to the forum and I did not want to accidently break any rules.

I would love to be able to identify the bad component on the board, but if I could at least confirm which board is bad that would help me out significantly. For the short term my toolset is basically limited to a Fluke DMM. I am willing to answer questions and follow directions if someone is willing to help with this problem. Thanks for reading.

[ricosavy]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

have u tried to do a channel scan.

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

I was told the cable input was what was connected during the storm and that it never worked again. When I tested it I used a DVD player set on the menu and the TV on CH 3. The DVD player was on and connected to another TV to make sure it was displaying. I only disconnected the cable from the other TV and connected it to the Plasma without disturbing the DVD player in any way. I could connect the DVD player back and run a scan and see if it hits on it. I plan on spending some time tomorrow looking at it again so I will give it a shot.

[bluto]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

I have a tuner for that board that I would be willing to part with for a minimal price. However if you can't get any display from any of the inputs (HDMI, component, s-video, composite), then you probably have bigger problems than just the tuner.

[selldoor]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Pictures are not really clear enough for trouble shooting - doesnt appear to be any board designations for parts so we would need to be able to see the parts
clearly. Please provide a link to the service manual or send it to Tom66

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Good pictures may be an issue, I was using the best camera I have available. I will explore my options on finding a better one. Until then I will work with what I have to see if I can get some better images out of it. I took those late in the evening after work and I did not have much time. For the pictures you need, in addition to being clear do they also need to be really close up shots so that values can be read? If I can get better results I will post them ASAP.

A link to the service manual however will not be a problem. You should be able to get it directly from the following link.

http://www.mediafire.com/view/?3hhmsi34wihyxro

or this is where I got it from



Thanks for trying to help.

Thanks for the offer bluto I at first was thinking tuner at first but with none of the inputs working it points to a common cause of failure for both the analog and the digital signals. The part I really find strange is that all the main chips that process these signals are able to pass the self-test, the tuners are also checked and pass.

[Mt.Man]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Most likely IC3001 on A board. All your missing signals go thru that IC.

Before you order any parts, make sure your TV is a U or UA model. Look at the little sticker on the back left side. If it lists your model as a TH-46PZ80UA it uses different boards then the U model even tho the the large back label still says TH-46PZ80U.

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Most likely IC3001 on A board. All your missing signals go thru that IC.

Before you order any parts, make sure your TV is a U or UA model. Look at the little sticker on the back left side. If it lists your model as a TH-46PZ80UA it uses different boards then the U model even tho the the large back label still says TH-46PZ80U.

Mt.Man,

Thanks for the heads up on the model numbers possibly being different. I have checked and they do match, it is only a TH-46PZ80U.

I have been trying to find a replacement "A" board but the places that I found them are out of stock or I am leery of buying from them. The board is a TNPH0721AES. If anyone can suggest a good place to source this board, I would be grateful.

Also, if anyone does not think this problem is on the "A" board which some may refer to as the small signal board I would love to hear from you.

Thanks!

[tom66]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

I am not certain, but the A board is likely to be similar between the TH-42PZ80U and TH-50PZ80U. Have you had a look for cracked screen plasmas of this model to see if you can find a matching board? Panasonic TVs are quite well built (failures are rare), but the one thing that does kill them is cracked screens.

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

A doner TV would be ideal because this TV will also need the power-board worked on or replaced once it will display channels. It has three big 220V 900uF Chemi-con KMQ capacitors that are starting to bulge. These capacitors are approximately 38X22mm in size but even if I could find them I do not know how to get to the back of the board. I would love to see how these boards are assembled as I have never seen a heat-sink/metal-plate attached to a circuit in such a manner.

I usually keep my eye on my local Craigslist for anything interesting but I had not considered looking under other cities in my area. I suppose it would not hurt to call some of the people that offer to buy broken TV's and see if they may have something useful. Are there some other places to look that I may not have considered?

[tom66]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

A doner TV would be ideal because this TV will also need the power-board worked on or replaced once it will display channels. It has three big 220V 900uF Chemi-con KMQ capacitors that are starting to bulge. These capacitors are approximately 38X22mm in size but even if I could find them I do not know how to get to the back of the board. I would love to see how these boards are assembled as I have never seen a heat-sink/metal-plate attached to a circuit in such a manner.

Are you sure about that? Can you post a picture of them? Seems odd that they would bulge...

I usually keep my eye on my local Craigslist for anything interesting but I had not considered looking under other cities in my area. I suppose it would not hurt to call some of the people that offer to buy broken TV's and see if they may have something useful. Are there some other places to look that I may not have considered?

Try posting adverts yourself "Looking for a Panasonic plasma that is broken for parts" etc. You should pay no more than $30 for a cracked screen 42" or 46".

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Are you sure about that? Can you post a picture of them? Seems odd that they would bulge...

Maybe I used the wrong word to describe the capacitors. The tops of the capacitors are starting to become dome shaped would be the way to describe it. It is slight at the moment but I think you can see it in the pictures. (I get home from work after dark and my camera sucks on close-up shots so I apologize for the quality of the shots.)

Try posting adverts yourself "Looking for a Panasonic plasma that is broken for parts" etc. You should pay no more than $30 for a cracked screen 42" or 46".

The idea to post my own ad looking to buy a broken Panasonic is brilliant. I will have to bait the hook and hope I catch a keeper.

[tom66]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Maybe I used the wrong word to describe the capacitors. The tops of the capacitors are starting to become dome shaped would be the way to describe it. It is slight at the moment but I think you can see it in the pictures. (I get home from work after dark and my camera sucks on close-up shots so I apologize for the quality of the shots.)

Those aren't bulging, it's normal mechanical stress for large caps. Bulging will look really bad if they were actually bulging... like these on the right: http://farm6.staticflickr.com/5119/7...92c1c1e8_b.jpg

Those are normally good caps but have bulged due to a failed Y-sustain board from a Hitachi plasma (when Hitachi actually made their own plasmas!)

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

Those aren't bulging, it's normal mechanical stress for large caps.

Thank you for that information!! That makes me feel much better. The big Panasonic capacitors on the board are absolutely flat if not concave and I was under the impression that any distortion in a capacitor was a bad sign therefore indicating they need to be replaced. Of course I am way over my head inside a TV, my limited capacitor experience is mostly with motherboards.

Hopefully all I will have to do now to get this TV working is find that "A" board. I really appreciate all the help from everyone.

[LDSisHere]

Re: Panasonic TH-46PZ80U - No Inputs, no sound but Menus work

I wanted to report back that I was able to get this TV working again. I replaced the "A" board originally a TNPH0721AES with a TNPH0721AKS. I had a repair place tell me that a TNPH0721AKS taken out of a TH-46PZ80UA tested good in a TH-50PZ80U. He then said that he thought that it would work fine in my TH-46PZ80U so I rolled the dice and came up a winner. I hope this information may help others in the future if they run into a similar situation. Thanks again to all those that took their time to read this thread and offer their input. This has been a great learning experience and I would say the most valuable is to never invest in a plasma TV.