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Equipment Repairs => LCD TV forum => Topic started by: thoma on January 11, 2012,10:29:18

Title: LG 37 LF65 LD 75A Chassis
Post by: thoma on January 11, 2012,10:29:18

Help needed!
This LCD makes me mad!The mistake is the following:Sometimes very seldom when i plug in
the power cord the lcd runs everything ok!The mostly time shorty the red led turns on then 5 times the
green leds flashes then short the red led comes and then no led is burning!no backlight is coming!
Has anyone of the specialists an idea whats the fault!
regards thoma!

Title: Re: LG 37 LF65 LD 75A Chassis
Post by: jimca007 on January 12, 2012,13:27:48

pop the back off and take a close pic of the power supply its the board the mains cable feeds into, at a guess because it's intermittent it could be secondary caps failing in the psu if you can get a pic we can get a look cheers

Title: Re: LG 37 LF65 LD 75A Chassis
Post by: thoma on January 14, 2012,09:54:14

The caps in the power supply are ok i have checked it with the ESR Meter
thoma

Title: Re: LG 37 LF65 LD 75A Chassis
Post by: lubos55 on January 14, 2012,10:57:00

Quote from: thoma on January 14, 2012,09:54:14

The caps in the power supply are ok i have checked it with the ESR Meter
thoma

Do not measure it,but change it.

Title: Re: LG 37 LF65 LD 75A Chassis
Post by: jimca007 on January 14, 2012,16:26:05

thats the problem with intermittent faults the caps, if thats the fault, may well test ok " sometimes " . If you catch the fault with the back off ie the stanby light flashes but tv doesnt start try heating the psu gently around the output caps with a hairdryer and see if you can then get it to switch on caps will raise their value slightly when the electrolyte is hot and drop value slightly when cold.

Title: Re: LG 37 LF65 LD 75A Chassis
Post by: thoma on January 18, 2012,09:44:09

I take a hairdryer and blow the caps but no reaction!!!
thoma

Title: Re: LG 37 LF65 LD 75A Chassis
Post by: jimca007 on January 18, 2012,12:00:14

well if you think the caps are ok and there's no signs of dry jointing on any of the psu's power components personally my next port or call would be to check the inverter coils for resistance and dry jointing, the inv caps for failure and the HT connectors for dry joints I usually just re solder all the HT joints on the tube connectors and transformers as a precautionary measure as its sometimes hard to tell if theres a prob or not.