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Equipment Repairs => LCD TV forum => Topic started by: jkost on August 19, 2009,18:47:54

Title: LG 32LC55 LCD TV inverter problem
Post by: jkost on August 19, 2009,18:47:54

hi

the chassis is the LD73A and after 15 mins there's no backlight the audio stays on for a while, then the appliance switches to standby, searching around the web looks like the problem is the power supply board..does anybody know where exactly the problem can be and if it can be fixed without replacing power supply?

thanks

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: Contrast John on August 20, 2009,12:45:47

Hi jcost
Sounds like a fault I had on a similar LG model. Check out my post on 23. 04. 09. as it has info on an LG modification to cure tripping to standby. Thanks also to tv tony for the details. These smd inductors are on the main pcb near the power board connector and have screened connections to chassis making them fiddly to replace. Care must be taken to avoid damaging the print.
Regards
John.

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: jkost on August 20, 2009,14:45:03

hi Contrast john

i took a quick look on the topic you told me...and it seems the problem is not quite the same...

the power supply got replaced today but the problem persists...the TV works fine for 10 monutes
then it flickers and then theres no backlight and goes into stand by.

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: tv tony on August 23, 2009,05:34:42

carry out the mods, the psu in these are very reliable, if you want details i will post them to you, tony walker

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: tv tony on August 23, 2009,10:19:33

here they are

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: jkost on August 23, 2009,15:06:35

Hello tv tony and thanks for the PDF... months ago Contrast John said

Quote from: Contrast John on April 23, 2009,13:37:09

Hi all
Thought this was going to be an easy one, but after replacing the domed and split electrolytics on the 5 volt line (power board) I was left with exactly the same symptom - relay clicking continuously at about 10 second intervals but the set not starting. While the relay is energised all voltages marked on the psu output socket are present and correct. Suspect some damage further downstream on the signals panel, possibly a damaged regulator or corrupt eprom. Has anyone encountered this situation before, or does anyone have a service manual / schematics for this model. Any advice would be much appreciated.
Thanks
John.

and you responded

Quote from: tv john on April 24, 2009,06:40:01

Go to the sm eeprom ic that sits near the LVDS plug on main pcb.Short the data & clock pins (?) on this ic,switch on and when relay clicks remove short.
 Tv should come on,enter service mode(sorry no info),set tuner to auto & select reset.
Thats all the info I have and never had to test it out.

Best of luck  tv john.

i hope  i'm not looking at the wrong posts... please give me more details because i don't think i understand the connection between the two problems.

since the replacement of the power supply didn't fixed anything i was about to believe that the CCFLs either they draw too much or too less current and the TV goes into stand by, but currently i don't have any replacement CCFLs so i can be sure.

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: Contrast John on August 24, 2009,11:58:09

Hi jkost
Think you`ve been looking at the wrong post. Check out the post on the LG set. (same date 23rd April).
Regards
John.

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: jkost on August 24, 2009,12:59:52

Quote from: Contrast John on August 24, 2009,11:58:09

Hi jkost
Think you`ve been looking at the wrong post. Check out the post on the LG set. (same date 23rd April).
Regards
John.

indeed!  :biggrin2:

so..what's the case with these inductors?  looks way to easy so the problem can be fixed...

as i said before still i haven't tested the CCFLs for defection because i don't have CCFL tester or replacement parts so i can exclude any possibility.

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: tv tony on August 25, 2009,01:12:22

hello, my company processes about 1500 lg sets a month and as such are account holders and we often fault find for lg, the sympoms you describe exhibit these faults, the ceratech filters (posh inductors) chokes, or whatever you may want to call them go leaky down to deck, i posted a shot from lg describing the fault, and if, as you say, you dont have any ccfl's what have you to lose, it would eliminate the issue for you, best regards,
tony walker

Title: LG 32LC56 LCD TV
Post by: remo80 on August 30, 2009,16:36:06

Sorry if I post a different topic  :mellow:

help with LG-32LC56 with audio stops and only after removing the current goes back into operation.

P.S. Please be soft updates

thanks

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: Ohm Supplies on September 06, 2009,11:46:08

I'd of thought the inverter would be the most likley cause of the fault, Check the 24v to see if its still there,

regards
Andy

Title: Re: LG 32LC55 LCD TV inverter problem
Post by: tv tony on September 07, 2009,04:32:56

i sent the memo from lg, the filters control, among other things, the control and brightness ctrl of the inverors, they go s\c (int)
by all means monitor the 24 line but you will need a min\max meter because if the 24 drops even by a small amount this will turn the lights out, i posted the bulletin from lg earlier in this topic, we havent had a single bouncer
tony walker