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Equipment Repairs => LCD TV forum => Topic started by: Turnip on December 09, 2016,05:13:35

Title: LG 37LF66 - Pic goes off
Post by: Turnip on December 09, 2016,05:13:35
Hi folks,

Have one where picture flashes off esp when set is warm - Sound/backlight continues. Had look on Ebay for an SSB, noticed an ad for SM caps to cure the problem.

Anyone know which caps to replace ? - Thanks - Chris.
Title: Re: LG 37LF66 - Pic goes off
Post by: bonesy on December 09, 2016,05:36:52
Hi bud,I think this set has the long thin power board,one of the electrolytic s on the top right hand side causes  inter pictures,either the bottom or second from bottom cap,I think may be a 620 or 820,may not be domed,just dropped in value,that Jordan fella will know for sure.
Title: Re: LG 37LF66 - Pic goes off
Post by: downunder on December 09, 2016,06:15:37

Hi Chris,

Ohms Supplies have a kit, but it's for no picture when cold and intermittent hor lines, so I'm not sure if it applies to your symptoms.

It includes C901, C945, C533, C970, C975, C915. Doesn't sound like a cap problem though.

Don't suppose it's got a FAN1507A33 3V3 reg on the main board. That can give slightly lower output after 15 minutes or so, resulting in NP, SOK, BL OK.

Bruce
Title: Re: LG 37LF66 - Pic goes off
Post by: michael first on December 09, 2016,07:34:04
Hi, Chris & Bruce

but if it's the same old story of bad inductors on the main board,of which TV Tony gave a cure some years ago?
Title: Re: LG 37LF66 - Pic goes off
Post by: bonesy on December 09, 2016,07:52:04
With the cap in the psu faulty,set comes on & works as normal,but picture goes off with scene changes,if it's that it's a quick fix.Had it a few times.Normally when the regulator & smd caps on ssb play up,picture breaks up into lines first,followed by blank screen!Normally will come back on if frozen.
Title: Re: LG 37LF66 - Pic goes off
Post by: Turnip on December 09, 2016,11:15:44
Hi folks and thanks for your thoughts,

Had another look at that Ebay site and attach info-

On YouTube - noticed an American chum who removes surface mount electrolytics cold just by twisting the case, where seems no track damage.

I always heat one side at a time and lift gently, but I've still lifted a track or two which is a bit of a pain, so bought some cheap tweezers that got incredibly hot but didn't have enough heat reserve to melt solder on normal telly panels - Chris.
Title: Re: LG 37LF66 - Pic goes off
Post by: bonesy on December 10, 2016,05:20:31
Are they the symptoms that your set is showing,that are listed on the sheet,or does your picture just go off ?If it starts with lines on picture/jumping/breaking up before going off,then regulator i.c. &  caps in kit.There was a mod for removing a number of smd chokes & replacing with wire links,there is an official lg mod sheet for this,sadly I don't have it,but I'm sure someone will have it.It cures all sorts of faults.
Title: Re: LG 37LF66 - Pic goes off
Post by: tv tony on December 10, 2016,11:51:52
While since Iv'e scanned on here. Will upload it, if it still exists!
Title: Re: LG 37LF66 - Pic goes off
Post by: tv tony on December 10, 2016,12:04:26
Well, it's still on the site, I'm amazed!
Remove L911, L912, L918 and L919 and bridge them. These were called ceratech filters and it was in fact me who discoverd this problem. At the time we did warranty work for LG. Many years ago. This was an official repair OK'd by LG and there was a bulletin at the time. But after looking at the circuit it all came back. The old Alzheimers hasn't finished me yet.
Title: Re: LG 37LF66 - Pic goes off
Post by: tv tony on December 10, 2016,12:09:05
Sorry, found it, hope it sorts you.
Title: Re: LG 37LF66 - Pic goes off
Post by: Turnip on December 14, 2016,11:01:48
Hi folks, and thanks for the help.

Whipped out the Ceretechs and replaced with links (Must get some zero ohm chips, as tiny wire links are a pain)
Set went off again, and of course it was IC900 the 3.5v reg as folks suggested, as a squirt of freezer sorted it for a while.
Surprised to find that 'High Street' - Wiltsgrove, do packs of five for less than 3 quid post paid.
Thanks again - Chris.