LG LCD TV won't turn on

 

New member
Username: Skor78

Post Number: 1
Registered: Dec-11
Hi,

I have a 26" LCD TV from LG, model 26LX1R, that won't turn on. It as the red light indicating power, but it won't respond to either power button on TV or remote.

Additional info:
- Symptoms started happening by not responding to power button in the morning, after turning on power cord, from 5min up to 1h until it worked.. until it finally died!
- The TV was connected to a protective power cord, that was switched off at night and on in the morning.
- TV was tested plugged into the wall, with a different power cord and in a different house (to test electrical distribution).
- I've dismantled the device to check if there was a problem with the capacitors in the power board, but everything seems fine.


Thanks in advance! Cheers!
 

New member
Username: Dtwilliamscomcastnet

Post Number: 10
Registered: Dec-11
Madz,

Do you have a multimeter and are you able to remove the back cover and take some voltage readings and/or check the status of a few fuses?
Without checking anything, it sounds to me like a Power Supply (P/S) problem simply based on the fact that it won't turn on at all. Checking fuses and output voltages will reveal more information so you can move forward.

Dave
 

New member
Username: Skor78

Post Number: 2
Registered: Dec-11
Hi Dave,
Thanks for your reply (finally one!),

I've opened it even before i posted here, like i said, capacitors seem fine, but without an ESR available it's difficult to be sure. I forced the tv on by shorting pwr connector with 5v (in standby i can only read the 5V, others (3.3V,6V,12V,24V) are off), i ear the switch "tlac", backlight and voltages come on, and seems fine, but it's hard to check everything because i have one hand occupied on the short and the tv on a precarious position..

It seems to me that the board/IC that is supposed to provide continuous 5V through the pwr connector is not doing its job.

But right now it's all still very blurry to me, i'm gonna do some more tests and post results. if you have any more suggestions they would be deeply appreciated.

Thanks!
 

Bronze Member
Username: Dtwilliamscomcastnet

Post Number: 11
Registered: Dec-11
Madz,

I think you have found the issue when you say, "...others (3.3V,6V,12V,24V) are off)..." If what you're saying is that you don't have all the voltages as listed, then it seems obvious to me that you have a bad P/S board. In electronics, it IS possible that P/S's can get "loaded down" by a down-stream failed component - but, since you are experiencing multiple failed voltage supplies, I would suspect the P/S board as the problem.

Dave
 

New member
Username: Skor78

Post Number: 3
Registered: Dec-11
i think you might misunderstood my English, sorry.

the voltages are off when the TV is on standby.
When i force power on, by shorting 5V with power on/off "line" that comes from main board through the connector, all voltages come up.
Are these voltages supposed to be up on standby?

Thanks.
 

New member
Username: Skor78

Post Number: 4
Registered: Dec-11
Hi,

New info. When i shunt 5VSB and PWR ON/OFF, tv works fine, even ON/OFF button on the dash works fine. Problem is, when it's shunted, and i plug it to the wall, the tv automatically turns on. I fear this can damage the tv with a power peak. Any suggestions?

Thanks!
 

Bronze Member
Username: Dtwilliamscomcastnet

Post Number: 15
Registered: Dec-11
Madz,
Without having the schematics to trace the circuit paths, it is somewhat hard to visualize just exactly what you are doing but, if I understand you correctly, you are shunting ("in parallel") a 5 volt power source so that the TV works. In my opinion, you simply have to determine which component in the PWR ON/OFF circuit has failed and replace it. I am assuming the 5 volt power was coming from the 5VSB circuit, correct? At first thought I was thinking you might just have a bad PWR switch but that wouldn't explain why it won't turn ON with the remote control.

You said, "It seems to me that the board/IC that is supposed to provide continuous 5V through the pwr connector is not doing its job."

I think you may be exactly right! See if you can find the specs on this chip and get the normal/expected I/P and O/P voltages and try and determine if the chip is bad or if some other component that is feeding the chip or is fed BY the chip is bad, (loading down the circuit).

Do you have schematics?
 

New member
Username: Skor78

Post Number: 5
Registered: Dec-11
Hi,

Sorry, been busy last couple days. Yes i have schematics, but in .pdf format from the service manual wich make them very hard to read. Even so i was able to follow the troubleshooting page and everything points to faulty part Q1001, which i'm not being able to find either onboard or in the schematics. Damn!

If you can help, i'd appreciate. If you want to check the service manual, just google "LG 26LX1R service manual" and you'll find a .pdf within the first page results. Also if you want to check more info on this, please read this thread.

http://www.tv-forums.com/forum/TV_Equipment_C4/TV_Repair_Forum_F3/LG_26_LCD_wont _turn_on_P126022/

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