Common LG TV Issue - Antenna Grayed Out

[R_J]

Re: Common LG TV Issue - Antenna Grayed Out

Does the other LG already have scanned in channels? if it does then it will show up in the input. If you were to delete all the scanned channels (or do a scan without an antenna) I doubt it would show up in the input as a selection.
The vcr does'nt need to play a tape, the rf modulator will still be outputing a signal.
The tuner pins should be available from inside the module.

[budwich]

Re: Common LG TV Issue - Antenna Grayed Out

"Problem is there is no exposed pin its on the other side of the board and no way to touch it without taking the board out!"
You misunderstand. You only need access to the three pins that your picture with meter already shows. Measure from those pins.

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

Are you sure - the three pins (i marked them on the pic below is that what you mean?) are actually to attach the sheath to the ground i just measured all three and they all attach to ground - i also measured the centre pin to the first diode in the circuit and to virtually every other point on the circuit board and there is zero conductivity so will remove the board tomorrow and check the centre pin, i think it must have a cold solder joint or summat?

Sorry I just read RJ posts again the pins you mean the little dots!
Thanks RJ you made it easier with the yellow lines lol
Blonde moment!
And don't you dare laugh and say typical woman lol
>;(

[R_J]

Re: Common LG TV Issue - Antenna Grayed Out

You may want to take a clear, in focus picture of the tuner module, remove the cable from the rf jack, the camera might be focusing on it.
In the module, the pins that connect the module to the main board "might" be accessable from the top, if not you would need to access the back of the main board.
By pins I mean the black plastic strips could hold the pins that go to the main board. The top part of the module has 2 rows, the lower part a single row.
Also the rf input center pin may be capacitor coupled as in this picture.

[budwich]

Re: Common LG TV Issue - Antenna Grayed Out

Are you sure - the three pins (i marked them on the pic below is that what you mean?) are actually to attach the sheath to the ground i just measured all three and they all attach to ground - i also measured the centre pin to the first diode in the circuit and to virtually every other point on the circuit board and there is zero conductivity so will remove the board tomorrow and check the centre pin, i think it must have a cold solder joint or summat?

Sorry I just read RJ posts again the pins you mean the little dots!
Thanks RJ you made it easier with the yellow lines lol
Blonde moment!
And don't you dare laugh and say typical woman lol
>;(

your picture is too out of focus to help see what is up. Your testing still doesn't prove that you have center "pin" connection from the coax to anywhere on the board. In "normal" connector design, I would have expected that some of those pins were connected to the center pin. Look closely at the connector to see what is happening. I am trying to stop you from doing too much "disturbing" of the system to prevent "oops".

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

Thanks Mr Bud i already had two "oops" Zsus boards go pop on me a diode transistor went up in smoke (twice lol) for forgetting a simple grounding screw - I did learn something though , always try and look at the positive through the tears!

I have multiple boards for this telly 5 ZSUS, 2 YSUS, 2 CPU, 2 PSU all except of course the IO board as its the most expensive £80 the rest cost me less than £50 for all of them - one of your Badcaps members even came out to my flat to help me fix the telly and brought me some free boards lol big handsome Scottish bearded hunk he was lol.

You are such a nice bunch of helpful men you have restored my faith in menkind haha
]

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

Well i tested all pin points today and no connectivity so I have been very naughty I removed the board and cut the rf input can/sheath completely off and soldered an aerial lead directly onto the earth and centre core and well I am a bit disappointed still no joy.

So i guess its the tuner module faulty somewhere but it will be difficult to backtrace the centre pin as it is all contained under the board which is hard soldered and clipped into the main I/O board so I guess that is as far as I can go - It would be a nightmare to replace the tuner board even if i could get a new replacement - I really need a new I/O board but at £80 its just too expensive so thank you gentlemen for being so kind and unless anyone has any other clever suggestions I am out of ideas and bid you all adieu!

I took a photo of the pinout if anyone needs it on here!

[budwich]

Re: Common LG TV Issue - Antenna Grayed Out

:-( this picture is better than the one you provided of the coax input. maybe take a better one of that area again.

on the picture that you just posted, did you check all the voltages that are printed on the board / connector pin area? still further.... where did you solder directly to the board AND before you did that "work", did you measure the resistance between where you soldered the center lead and the shield of the coax? one other question, what area / card exactly is the recent picture of?

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

Its the back of the tuner area where you mentioned the pins - those are the pin designations printed on the back of the circuit board.

I soldered the coax directly to the centre pin and the copper shield to the earth casing.
Still no reading.
Checked all the pins again still no reading on any of the pins.
Checked before and after "work"!

No have not checked the voltages - I will do tomorrow and take another photo of the tuner section!
TV is still working...Amazingly.....after my "work"!
>;o)

[budwich]

Re: Common LG TV Issue - Antenna Grayed Out

:-( its tough without a schematic but you should be able to do some "blind checks / tests / tracing". With you meter on "continuity" (ie. buzz for a short) or just plain resistance testing, with one probe on the center pin, use the other to touch various components in and around the area near the center pin area.... you may / should find some continuity close by.... hopefully.

Further, can you highlight in the previous picture exactly which spot you soldered to what?

[R_J]

Re: Common LG TV Issue - Antenna Grayed Out

The RF input center conductor is very likely coupled to the rest of the tuner input circuit via a very small smd cap. They do not feed the rf cable directly into the rf ic. Do the simple checks first, on the bottom of the board, check if you have 3.3v, 2.5v, 1.2v and +B. I'm sure these voltages are accesable from the top within the tuner module. The rest are mostly clock and data lines so a scope would be needed to check them.
I don't think I have ever seen a just a broken center pin, it usually the whole jack that is either loose or completey ripped out.
Also I suggested scanning an analog rf signal, they are usually easier to scan and find then a ota digital signal.

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

Copper core of coax soldered to central pin that is cut.
Braid soldered to outer can that is now cut!

Only one voltage 3.3v present on the array of pins!

Already tried numerous raw rf inputs from other devices vcr, youview, tivos etc and no joy.

Measured voltages to various points but no joy although the large what looks like a lime green inductor shows a 1.5v voltage!

[mmartell]

Re: Common LG TV Issue - Antenna Grayed Out

If I remember there should be a higher voltage - around 30v, driving the tuner module.

You don't need the schematic for that TV if you can find another that uses the same tuner module.

[R_J]

Re: Common LG TV Issue - Antenna Grayed Out

The 30 volts was the VT (tuning voltage) on old style tuner modules and many times was created within the module, and the VT pin was just a reference output pin. It is not used in this type of digital module.
The only voltage that I see that could be missing is the B+ on pin3 which is usually +5 volts.

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

I am beginning to wonder if i can remove the tuner module and test it off the main board.

I have a reflow oven and a hot air gun and soldering station and am pretty good with them!

I just bought one of those cheap build it yourself oscilloscopes from Banggood do you think it would be of any use? - i know they only go up to 30v i think so no use for mains testing but i am quite interested in learning how to use an oscilloscope as part of my learning curve so if the tuner is only 5v it might show me something?

Do you think that lime green thing is an inductor or a resistor - is there a way to tell and inductor from a resistor?

[budwich]

Re: Common LG TV Issue - Antenna Grayed Out

building your oscilloscope can only help. I think there are a few test points / signal points that are labelled that may tell you more about what's going on and thus if you see something / anything at those points can only help. Having said that, I think you are missing some labelled voltages and thus the tuner section is not functioning properly.

Further, back to your measurements of the pins where you indicate only a 3.3v and nothing else. You need to measure ALL pins not just ones that have "V" labels. present this with "pin label" "value" in some "table like" form. The reason for this is some of those provide "state information" (eg. "ERR") which may indicate what is happening depending on what the reading is.

[R_J]

Re: Common LG TV Issue - Antenna Grayed Out

That "lime green" thing IS an inductor. DO NOT apply 30 volts anywhere on this tuner. If you have a scope, use it to look at the clock and data lines if you like, once the tuner has been removed it will be imposible to work on.

[brucetv]

Re: Common LG TV Issue - Antenna Grayed Out

Reading this reminded me of a repair with this problem on a LG Plasma and I went into settings and noticed the setting was on cable. I switched it over to Antenna but it would not highlight Antenna so I tried switching back to Cable and then back and my Antenna highlighted on the 2nd try, ran a channel scan and it scanned fine and was not greyed out anymore. I wasn't as lucky on other models but it worked fine on that model and didn't need a main board replacement. Try that and see if you get lucky. Also on the TCL Tv's I would avoid them like the coronavirus because we see a lot of them coming in for backlight repairs after 14 months of purchase and it can be difficult to get new backlight kits for them. I was impressed by some of the higher end TCL's at the CES show this year. Picture quality was good but the quality of the components on their Main Video boards really sucks. My guess is they are using good quality panels but sparing on the quality chipsets with premature failure rates. The salesman said they are going after Hisense's market share but neither one is a good buy in my opinion. Keep the backlight settings down low on both TCL's and Hisense's especially when its difficult to get new kits for both.

[Lydia]

Re: Common LG TV Issue - Antenna Grayed Out

Thank you i did check all the ;ins only one with a voltage present but i think the tuner is snafu although i am going to try and test is more thorouglhy when i build the oscilloscope and meantime will remove the board and do some individual component tests on the resistors and other componenets - the inductor does have a voltage going through it it was the only thing with any voltage present but i needd to take the board out and have it on the workbench to properly test it!

Thank you gentlemen for your kind assitance.
Yes bruce i tested everything i could before i came on here including your suggestion but its a tuner issue although i am going to try a usb reflash of the firmware to see if that perhaps can cure the problem although its a long shit!