Panasonic Plasma TH46PZ85U tuner problems

[bluto]

My folks have a 46" Panasonic Viera Plasma TV. It is slightly more than 18 months old. They have only expanded basic analog cable + clear QAM channels playing through the internal tuner. The problem is that recently about half a dozen channels (no particular order here) have decided to not play any sound. It is always the same channels and yes I did check the other TVs in the house and the problem is not with the cable feed. I was told that once the turner also 'went crazy' and was continually scanning through all the channels without stopping. Apparently a power cycle cleared that up and I have not been able to get it to repeat that.

I haven't taken apart yet. I am hoping that it is some bad caps
Has anyone ever heard of this? I did some googling and found some references to tuner problems on panasonic plasmas, but nothing for this model. There was a post over at AVS that talked about upgrading firmwares, gave a link to a site, but that site is now password protected.

It seems that even a good brand like Panasonic is not worth much for quality these days. I would expect these kind of problems on a wal*mart special after 18 months, but this was hardly such.

[bluto]

Re: Panasonic Plasma TH46PZ85U tuner problems

I found the part number of the main board to which the tuner is attached (TNPH0721ASS). Looks like an expensive part. The tuner module (ENGE6608KF) is available separately for ~$50. Would replacing the tuner module on the main board solve the problem with the set? Any tips?

Also saw this: www-tiptoptuner-com (they were keyword bombing google with tuner part numbers). They promise to fix any tuner for $27. Anyone ever used them?

[bluto]

Re: Panasonic Plasma TH46PZ85U tuner problems

I just got a chance to examine the TV. Channels 6, 28, 29, 32, 49 & 95 have no audio. So no obvious pattern there. The cable system there has analog channels up to 78 (with a few gaps in between) and 95 & 96 in the funky FM band of channels.

I took a frequency chart (http://www.jneuhaus.com/fccindex/cablech.html), made it into a spreadsheet and highlighted the channels that are out. No obvious patterns there except the relationship between ch. 6 & 95 on the spectrum.

[shovenose]

Re: Panasonic Plasma TH46PZ85U tuner problems

Odd. So you didnt find any bad caps?

[bluto]

Re: Panasonic Plasma TH46PZ85U tuner problems

Have not had the time to take it apart yet.

[shovenose]

Re: Panasonic Plasma TH46PZ85U tuner problems

Then how did you mske a picture of the board?

[bluto]

Re: Panasonic Plasma TH46PZ85U tuner problems

I came up with the picture from a site selling the main board. Found that based on the model number. At some point I am going to open this thing up to see what is going on. But being a Panasonic, one could assume that it should have Panasonic caps in it. I guess there is only one way to find out for sure.

[bluto]

Re: Panasonic Plasma TH46PZ85U tuner problems

Well I finally decided to tackle this one. I got a replacement tuner module for around $50. To make a long story short, I soldered it in there and the problem with some channels not having sound remained.

So in the normal course of fiddling around, I came across the 'reset' menu. Had to give it a password (don't remember setting one), so I tried 1234 and amazingly that worked. After completing the reset and re-scanning channels, I was amazed to find that the previously soundless channels now had sound. So I solved the problem, but wasted $50 on an unnecessary tuner replacement. If anyone needs an ENGE6608KF tuner module, PM me and I will sell it cheap.

Final thoughts: This was the first plasma that I have ever cracked open (have done lots of LCDs). I was almost dumbfounded with all the circuit boards inside, especially those having to do with the HV stuff driving the panel. I was also impressed with the build quality of the Panasonic. There was a lot of detail paid to everything all the way down to the cable tie down clips. Didn't see any Panasonic caps (not eating your own dog food) but lots of Rubycon and Chemicon (no cheapo teapo).

In the end I am a little frustrated with the software bugs in this unit. This tuner problem was one of them. And it also has an issue of having multiple instances of a given clear QAM channel after the cable co shuffles them around (they frequently do). The old channel, now a 'ghost' channel, cannot be deleted. The factory reset took care of them, but that shouldn't be necessary to delete a channel. Is there any way to possibly obtain a firmware update? Although that is probably a long shot since manufacturers usually don't fix bugs on the old model unless it is severe enough to get lots of customers pissed off.

[PlainBill]

Re: Panasonic Plasma TH46PZ85U tuner problems

You could try the Panasonic TV support website. I do know Philips makes firmware updates available and has a relatively simple process for installing them.

PlainBill

[bluto]

Re: Panasonic Plasma TH46PZ85U tuner problems

Good idea. I googled the relevant terms and found this:
http://www.panasonic.com/announce/up...tv/service.asp
Only three models listed though. I guess those firmwares were really borked in version 1.0. It mentions loading them from an SD card. That would be nice.

The AVS post from 2006 that I was referring too at the top of this thread:
http://www.avsforum.com/avs-vb/archi.../t-750920.html

It mentions a site to get firmware (http://www.pasctraining.panasonic.co...downloads1.asp). But it is apparently now password protected.

Any idea on how to obtain the goods? Or just to know if updated goods are available for this model? A search on the forum revealed no other references to 'panasonic' and 'firmware' except this thread.