LG 42lg50 Channel Memory Problems

[Spitz]

Tv works perfect except that it looses the channel list. Channels will disappear or it will display wrong channel. Not too serious of a problem because you can scan channels after you turn it on and it will work for the rest of the evening. But the next day, it will be messed up again. It seems to be a storage problem, like a flash memory chip. Does anyone know where they are stored? There is the main board, and a control board, or are they stored within the tuner. I have gotten a copy of the service manual and replacement boards are available, but I am not sure where the channel list is stored.

[tmwalsh]

Re: LG 42lg50 Channel Memory Problems

Don't know the specifics, but you can take the IC identification and google for a description of the specific device. Look at the drawings or schematics for something labeled static ram or NVRAM. This chip might be defective, or the 'keepalive' circuit used on some sets may be intermittent, thus allowing the memory to leak down.
Did the set keep things memorized after it was unplugged or lost power previously? If it did not keep things remembered, and you had to re-scan after a power hit, then it could be the keepalive power. If it kept things remembered over a significant power outage, then it likely has NVRAM, non-volatile RAM, which keeps its memory w/o power.
So, it could be a bad solder joint supplying the power to the memory, or a bad chip.
Just my opinion.
tom

[Spitz]

Re: LG 42lg50 Channel Memory Problems

Don't know the specifics, but you can take the IC identification and google for a description of the specific device. Look at the drawings or schematics for something labeled static ram or NVRAM. This chip might be defective, or the 'keepalive' circuit used on some sets may be intermittent, thus allowing the memory to leak down.
Did the set keep things memorized after it was unplugged or lost power previously? If it did not keep things remembered, and you had to re-scan after a power hit, then it could be the keepalive power. If it kept things remembered over a significant power outage, then it likely has NVRAM, non-volatile RAM, which keeps its memory w/o power.
So, it could be a bad solder joint supplying the power to the memory, or a bad chip.

Got a copy of the service manual and a picture of the main board. Do not see a battery on the main board. Found out the control board is for the lcd screen. The power flow diagram shows three eeproms but don't know what they do. Thanks for the response and opinion. Will continue to dig for information.