Panasonic TX-L55ET5Y can't find channels

[Khron]

So i've had this 55" "behemoth" brought in the other week, saying it won't see / find TV channels anymore.

Upon a quick consultation, Th3_un1qu3 suggested i resolder the pins of the RF block itself. Diligently i did so, both on the mainboard connections, as well as inside the shielded can itself, just to be on the safe side.

After i let things cool back down, i plugged it in, stuck the cable connector into the appropriate socket (had to find the right position for it - the only cable i had available had a threaded male F-connector, and the tv has a "normal" female Belling-Lee). Lo and behold, it worked! Did an auto-search, it found all the DVB-T channels broadcast around here.

After that, i reassemble it (ie. mounting the metal back cover and reattaching the stand). Guess what - it fails to find channels again

I re-did the solder joints, "just to be sure", but i'm running out of ideas here

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

Just for kicks, i looked up the mainboard on fleabay, 73 pounds / 85 euros/$ and up - ouchie...

Then i remembered seeing a label on the tuner can itself, that can apparently be found for about 31 pounds / 36eu, which is a bit more bearable.
EDIT: Found a few other sources around Europe, for under 20eu plus shipping.

Then i decided to google the part number, and among the first few results was this listing (gotta love the description)
http://www.ebay.co.uk/itm/PANASONIC-...oAAOxyuDpSE0yn

I guess it's a reasonably commonly-occuring issue then?

[CapLeaker]

Re: Panasonic TX-L55ET5Y can't find channels

Did you check the rf connector on the tuner module for damage? Maybe the solder joint is broken and you temporarily fixed it by acing the coax a certain way forcing the connector making contact on the bad joint?

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

I resoldered that too in the second round, "just in case", and it didn't help.

[tw2005]

Re: Panasonic TX-L55ET5Y can't find channels

Sounds as though heat soaked into the tuner module and it worked then cooled down and not working.

Why not replace just the tuner module?

What numbers are on the tuner?

ENVS9302D5F ?

[tw2005]

Re: Panasonic TX-L55ET5Y can't find channels

If you look at this ebay link for GTV Watford who's a specialist Panasonic tech he even lists this module as a fix for No Tuning . Must be known or common problem.

"PANASONIC TX-L32E5 TX-L37E5 TX-L42E5 (NO TUNING) ENVS9302D5F REPLACE TUNER"

http://www.ebay.co.uk/itm/PANASONIC-...p2047675.l2557

[tw2005]

Re: Panasonic TX-L55ET5Y can't find channels

http://tectronelectronics.eu/en/pana...?sef_rewrite=1

http://www.chsinteractive.co.uk/elec...f-txl32e5e.htm

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

Have you even read my first two posts? Especially my second one...

[tw2005]

Re: Panasonic TX-L55ET5Y can't find channels

got the first missed the second, since you were still responding to soldering suggestions I thought that you were still at that point.

Could not tell from the link it was the same, great minds think alike I guess.

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

Granted, my google-fu isn't quite as strong as some others', but that much i DID manage to figure out on my own Had you even clicked that link, at least?

Just for the hell of it, and 'cause it's free and at hand, i'm about to give reflowing the tuner chip a shot. I mean, since it can't find channels anyway, what further harm could it do?

[tw2005]

Re: Panasonic TX-L55ET5Y can't find channels

[dick_barton]

Re: Panasonic TX-L55ET5Y can't find channels

Granted, my google-fu isn't quite as strong as some others', but that much i DID manage to figure out on my own Had you even clicked that link, at least?

Just for the hell of it, and 'cause it's free and at hand, i'm about to give reflowing the tuner chip a shot. I mean, since it can't find channels anyway, what further harm could it do?

Are you going to open up the tuner? It could be something as simple as the aerial input wire has broken; however it will allow you to resolder the joints you can see. And as you say there's nothing to lose.

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

As you can read in the first post, i had already opened up the tuner can itself (just had a clip-on lid). And as can be seen in post #4, i've already done that too (input resoldering), but to no avail.

I've just reflowed the tuner chip, ie. took off the top cover and stuck the ~6mm nozzle of my hot-air station onto it, with a smattering of flux around it, and poked it until it moved.

Seems to have cooled down now, so lemme just plug the board back in.

Result... Precisely the square root of absolute squat.

Ah well, as soon as the people at CHS answer my email, i'll be ordering a tuner from them.

[dick_barton]

Re: Panasonic TX-L55ET5Y can't find channels

I missed that you had already open the tuner can. Pity it didn't work out.

[CapLeaker]

Re: Panasonic TX-L55ET5Y can't find channels

I hope the tuner replacement does the trick. I am sure you checked the voltage that powers the tuner too...

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

I couldn't find the service manual for this exact model, only for a "close enough" one, but both the 3.3v and the 1.8v going to the module, measured on the bypass caps near it, checked out fine.

Just double-checked, measured all 10 or so pins inside the can, and they all seem fine. one 1.8v, three or so 3.27v, 1-2 ground pins, 2 pins 0.6v or so, and one bouncing all over the place (likely the signal or data pin, i measured this with the tv doing a channel auto-scan).

[mmartell]

Re: Panasonic TX-L55ET5Y can't find channels

I remember tom66 long ago stating these tuners have a supply of 30v or so not sure why yours doesn't?

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

Was it this exact model of tuner?

Not quite sure why it would have a 30v supply, it's a chip-based one:
https://cdn.badcaps-static.com/pdfs/...035ecf8406.pdf

[mmartell]

Re: Panasonic TX-L55ET5Y can't find channels

Was it this exact model of tuner?

Not quite sure why it would have a 30v supply, it's a chip-based one:
https://cdn.badcaps-static.com/pdfs/...035ecf8406.pdf

Here is one for instance

https://www.badcaps.net/forum/showpo...35&postcount=2

If you search "33v" and user "tom66" you will see several instances where he discusses it.

[Khron]

Re: Panasonic TX-L55ET5Y can't find channels

That may have been the case for analog tuners, perhaps. As i've mentioned, this one's a chip-based one.

EDIT: I just looked up the TV model from the title of the thread you linked - it's from 2004 apparently (or at least there's a cnet.com review dated in 2004). This one i have issues with is a 2012 model.

I've googled for the mainboard code, and i've (once again) found the service manual for Panasonic TV different from this one, but with the same mainboard. you'll find the tuner "socket" pinout on page 53, on the left side:

amigosdaeletronica.com.br/downloads/?sa=downfile&id=102

As you can clearly see, no "high-ish" voltages there. IF AGC pin, two IF pins, 1.8v supply, reset line, SDA/SCL I2C bus, 3.3v supply, another IF AGC pin and two IF pins. As previously mentioned, both the 3.3v and the 1.8v supplies are fine.

I've also run the I2C self-check test, as per page 11, and everything is ok (apart from the wifi dongle which wasn't plugged in).