LG dual tuner smart tv intermittent fault.

kaizer13

Satellite reception had been perfect for five months then loss of horizontal channels prompted me to change LNB. Success, all ok for a couple of weeks then horizontal channels disappeared again. Refitted original LNB and all worked fine again...maybe not LNB fault after all.

Couple of weeks of reliable viewing and then all satellite reception failed. Now as dish is in temporary location, at just above ground level on wooden fence post it was felt prudent to prune away potentially threatening tree and bush branches which may now have overgrown their welcome and might be obscuring signal. Made no difference. Cable connections between TV and LNB all checked for shorts and continuity and entire length of coax inspected for possible rodent attack. Some evidence of mouse nibbles through outer insulation where the cable runs through undergrowth, the bitten section was cut out and cable re-made. TV switched back on and all horizontal and vertical channels worked....for a couple of days.

As no clear cause had been found and after each testing and checking operation all would work ok for a while it was decided that my dish alignment meter that also monitors LNB supply voltage should be brought into the investigation. With the meter being used purely as a voltmeter on the end of the TV LNB connector to wall outlet plate connecting lead it was found that occasionally when TV was selected for a horizontal channel, there would be no LNB supply voltage. If the circuit to the LNB was completed by connecting the meter to the wall plate, then horizontal element supply voltage and signal reception was restored. The meter was left in circuit dangling beneath the TV for a week and all worked perfectly, albeit a little unsightly.

Upon removing the meter from the connecting lead to the wall plate, the intermittent problem has returned, almost as if the coax lead needs to have the meter permanently connected in, in order to secure reliable operation! I have now discovered that whenever the reception disappears, I can "reset" the LNB supply to that element by simply disconnecting and then reconnecting the lead at the wall plate connector. This has to be done whilst the set is powered up and in reception mode. It is almost as though the LNB supply circuitry in the TV needs an occasional kick.

Does anyone have any thoughts on this?

Johnboy1951

When the fault occurs does unplugging the TV for a short time, and powering it up again make any difference?

Could it be the psu providing the LNB power is failing or not providing sufficient current over the distance to the LNB?

Is the coax run a long one?

Do you have another device you could use (such as STB) for testing?

Thurston?

kaizer13 wrote: »

... Upon removing the meter from the connecting lead to the wall plate, the intermittent problem has returned, almost as if the coax lead needs to have the meter permanently connected in, in order to secure reliable operation! I have now discovered that whenever the reception disappears, I can "reset" the LNB supply to that element by simply disconnecting and then reconnecting the lead at the wall plate connector. This has to be done whilst the set is powered up and in reception mode. It is almost as though the LNB supply circuitry in the TV needs an occasional kick.

Does anyone have any thoughts on this?

What about the wall plate itself? You must be happy enough with the cable connection inside it? Maybe you tried bypassing it?

STB.

Just make sure the braid isn't touching the core on the satellite connector as that could cause these issues.

What is more likely is that your cable run is too long.

Unlike most set top boxes, TV sets don't have the option to supply increased power for long cable runs.

Junctiong the lnb and cable to box with an Inline Satellite amplifier might help.

kaizer13

Johnboy1951 wrote: »

When the fault occurs does unplugging the TV for a short time, and powering it up again make any difference?

Could it be the psu providing the LNB power is failing or not providing sufficient current over the distance to the LNB?

Is the coax run a long one?

Do you have another device you could use (such as STB) for testing?

Powering down, unplugging and then switching set back on makes no difference.

Coax length is not excessive although as it is a temporary installation about 20 metres of it lays on the ground and among grass and weeds.

I do have an STB to try but I am sure that if I hook that up, everything will work perfectly again.

I am getting the impression that the TV power supply to the LNB is being loaded or tripping out due to some external influence.

It has been decided to relocate the dish to a more secure and sensible location and with a new and shorter length of coax.

Thank you for your interest. Watch this space...

kaizer13

Thurston? wrote: »

What about the wall plate itself? You must be happy enough with the cable connection inside it? Maybe you tried bypassing it?

Have removed wall plate which has independent LNB and UHF outlets and checked for poor connections and possibility of shorts...all looked ok.

The difficulty is that whatever testing, measurement or visual examination is carried out and even when nothing has been found to be amiss, the satellite reception then works ok for a while.

Thanks for your response.

kaizer13

STB. wrote: »

Just make sure the braid isn't touching the core on the satellite connector as that could cause these issues.

What is more likely is that your cable run is too long.

Unlike most set top boxes, TV sets don't have the option to supply increased power for long cable runs.

Junctiong the lnb and cable to box with an Inline Satellite amplifier might help.

All connections have been checked for whiskers shorting and have been re-made, just in case. So that eliminates those possibilities.

Comments regarding coax length may be valid in this case. Although there were no problems when this installation was used with a previous TV and STB the supply in the new TV may not like the cable loading.

It has been decided to relocate the dish and a much shorter coax run will be used.

Thank you for your interest and your response.

kaizer13

Relocating the dish and halving the cable length appears to have sorted the problem we now have perfectly reliable reception.

Thanks to all for your comments and interest.