LG 55LM7600 Tv won't turn on

[Nick's Tvs]

I noticed that there was almost no information about this model TV on the forum, and I recently just fixed one for a customer so I wanted to share the info since I have seen this set twice in the last couple months with the exact same issue.

You try to power on the tv but the little LED just blinks a couple of times and the set stays off.
In both my situations, the Power supply board AKA SMPS with part number EAY62512802 was the cause of the issue.
On the upper left quarter of the power supply, you will find a blue ceramic capacitor C603 and a diode D607. In one case, I had both the diode and the ceramic capacitor go out, and in the other I had just the capacitor. They pretty much just short out. The blue capacitor has 221k value, and the diode is
MUR460AX so 4amp forward current 600v reverse voltage.
http://pdf1.alldatasheet.com/datashe.../MUR460AX.html

Now I do want to point out to anyone in the same situation that the diode will register shorted in circuit if your cap is burnt. So make sure to test both out of circuit to be sure.

This also more than likely occurs on the EAY62512801 board as well

[joezag]

Re: LG 55LM7600 Tv won't turn on

Thanks Nicks Tv for the tip. Same two parts fixed my set. I have a repair shop and its techs like you who make my day brighter.

[68pishta]

Re: LG 55LM7600 Tv won't turn on

Just scored one from the curb. 3 flashes of led and that's all I got. Took power supply board out and checked voltages. Seemed like I got 22V on all the primary side caps, and no standby voltage? Tested voltage across the T5A H 250V fuse and got 97V on one side and 24V on the other? tested open on my VOM. Installed a 12A ceramic fuse with some solder and the board blew the solder connections right off, sounded like a firecracker! So Im wondering if the board is completely toast now or if the 5A fuse just needs the proper solder job (socketed ends on good solder) and the 2 suspect components replaced? I thought I saw a crack in the screen looking from the side but after I cleaned it I dont see any sign of a crack, but Its not backlit so.....Doesnt look like any physical impact damage to the decorative metal frame but the back metal panel has a few dings in it. Would you be able to see a damaged screen by inspecting it from the top or could a crack hide under the first layer?

[68pishta]

Re: LG 55LM7600 Tv won't turn on

Here is the EAY62512802 board with fuse at bottom corner. If the diode and cap were shorted, would that explain the 22V I saw on the board with the fuse testing open, and maybe the new fuse popping (although the 12A ceramic never blew, the solder joint did)??

[monty15]

Re: LG 55LM7600 Tv won't turn on

Greetings

Check on the backlight with the tester if it's Ok.
There are two : Defect in PSU or eeprom in mainboard.

[68pishta]

Re: LG 55LM7600 Tv won't turn on

221K 220pf cap blown, shows 4040ohm with a big black burn hole in the middle. Diode tests OK. Dont have backlight tester. Where is backlight voltage pins or what pin voltage is backlight?

[68pishta]

Re: LG 55LM7600 Tv won't turn on

UPDATE
Replaced the 5A slow blow fuse, replaced the 221K capacitor, checked all the diodes and plugged it in. The lower 3 pin MOSFET(?) on the small heatsink quickly burned to a crisp. New $35 power board time..and I dont even know if the screen is any good. I guess Ill work an hour of OT this week to cover that.

[nomoresonys]

Re: LG 55LM7600 Tv won't turn on

Good plan, an hour overtime beats 20 hours messing around with that powerboard.