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Equipment Repairs => LCD TV forum => Topic started by: Davy on February 12, 2019,15:19:19

Title: LG 42LG7000 strange fault.
Post by: Davy on February 12, 2019,15:19:19

Got this 42LG7000 TV... never seen this fault before.

The red standby LED flashes a couple of times, comes back on a slightly longer period then fades out then flashes again repeating the sequence.... the backlight supply is dead as a dodo yet everything 'seems' to check out on the power board..... no bulging caps that I can see so thought I ask what's it telling me first?

Dave

Title: Re: LG 42LG7000 strange fault.
Post by: downunder on February 13, 2019,01:54:05

Hi Dave,

Common fault on LGs is the main board fails to send the INV-ON signal to the psu to activate the backlight CCFLs. Check this at the main-to-psu connector on the PSU as the set attempts to start - should get up to 3.5V approx.

Just a thought. I could be leading you up the garden path, but you have to start somewhere. Cooking the main board might produce results and reduce fault finding.

Bruce

Title: Re: LG 42LG7000 strange fault.
Post by: Davy on February 13, 2019,09:12:06

Ah that explains all. Many thanks Bruce, fully appreciated.... the slow dimming 'had me'.

It did come on after the last attempt but the backlights didn't look too good, think I'll advise to scrap seeing the age, the main board SMD caps. looked OK think it's best to leave it at that.

Must say the main board is well protected with metal but not the power supply.

Dave