LG 55LV5500-UA no picture or sound

[electrobe]

Re: LG 55LV5500-UA no picture or sound

I was able to find a schematic drawing & here is a picture of the circuit where the part was burned.

[budm]

Re: LG 55LV5500-UA no picture or sound

That is the power MOSFET that supplies the 12V to the T-CON fuse, isn't it?
That MOSFET is being used as a switched so for it to burn up it must have too much current draw through it so I would check to see if the load side (Drain pin) of the MOSFET has very low resistance or not.
Can you upload the whole service manual?

[electrobe]

Re: LG 55LV5500-UA no picture or sound

Here are the circuit boards service schematics you requested.

[electrobe]

Re: LG 55LV5500-UA no picture or sound

After finding the board service schematics I did the additional tests as follows.
1.) Checked stand by voltage on (P501 pin 9-12 +5.5V) GOOD
2.) Checked micom voltage (IC602 pin 48 +3.5v) GOOD
3.) Checked (P501 PWR_ON 1-pin 3.3V) GOOD
4.) Checked multi voltage (P501 2-pin: 24V, 17-pin: 12v) GOOD
5.) Checked (IC501: 0.9V, IC504: 2.5V, IC505: 3.3V, IC508: 1.5V) GOOD
6.) Checked (Q507: 12V) NOT GOOD BURNED WITH A BUBBLE ON TOP
7.) Couldn't check inverter control P501 pin-18 because of previous burned mosfet
Checked for no video ic's proper voltages
1.) Checked tuner 5V (L2104, L2101) GOOD
2.) Checked tuner 3.3V power (L2103) GOOD
3.) Checked tuner 1.25V power (IC2103 pin-2) GOOD
4.) Didn't know how to check tuner signal so I skipped this
5.) Checked BCM LVDS Output voltage (pin-45-51 11.51V I received when checked) (pin-7 I had no voltage)
I am not sure what I should check next or if the burned Q507 & possibly tuner is my problem.

[budm]

Re: LG 55LV5500-UA no picture or sound

'6.) Checked (Q507: 12V) NOT GOOD BURNED WITH A BUBBLE ON TOP' So did you check the resistance between the T-CON fuse and GND to see if it shows low resistance reading?

[electrobe]

Re: LG 55LV5500-UA no picture or sound

The t-con fuse resistance reading was 12.87 kilo ohms. Does that mean it is bad?

[dick_barton]

Re: LG 55LV5500-UA no picture or sound

The fuse resistance when measured across it should measure 0.0 ohms.

Edit
If the reading is from the fuse to ground then that appears to be a reasonable.

[electrobe]

Re: LG 55LV5500-UA no picture or sound

ok thanks I guess I will have to replace it also.

[thoma]

Re: LG 55LV5500-UA no picture or sound

http://alpengeist-tvrepair.blogspot....-clicking.html

[electrobe]

Re: LG 55LV5500-UA no picture or sound

I thought I would give you an update on the tv repair. The tv is fully working now with no problems. The main problem was the BCM (IC101) was whiskered (wouldn't give the 3.3V on the output to the LVDS on pin 7) & needed a reflow. I preheated the board to 200 C & then slowly increased the temperature on the IC until 220 C for 15 seconds.

[Ashish_Jamesh]

Re: LG 55LV5500-UA no picture or sound

no audio and no video on LG 47LX9900 3D LED TV. It respond with remote and physical buttons. Please help me to solve my issue.

[budm]

Re: LG 55LV5500-UA no picture or sound

no audio and no video on LG 47LX9900 3D LED TV. It respond with remote and physical buttons. Please help me to solve my issue.

You need to start a new thread with make and model AND pictures of the whole backside of the TV so we can see how all the boards are connected together.

[Ashish_Jamesh]

Re: LG 55LV5500-UA no picture or sound

I am new to this forum and don't know how to start new thread. Please guide me....

[tvfixer007]

Re: LG 55LV5500-UA no picture or sound

I have a 55LW5600 with the same issue. What causes MOSFET (Q507) to burn? A short on the t-con board?

[dick_barton]

Re: LG 55LV5500-UA no picture or sound

Check the fuse on the Tcon to see if it is open circuit using your meter set to ohms and place your probes across it with the set switched off. If that is open then probably something on the tcon board has taken it down. If not then need to look elsewhere.

[tvfixer007]

Re: LG 55LV5500-UA no picture or sound

Fuse is open on the t-con board. Probably best off replacing the whole board but I'm going to see if I can find out what's wrong with it.

[tvfixer007]

Re: LG 55LV5500-UA no picture or sound

I found a bad cap in the attached image. Cap reads 1.5-1.8 ohms in circuit and out of circuit. The other cap next it read the same until the bad one was removed. Which was quite difficult to remove but finally got it out.

Other image is for whatever reason. I stepped on my soldering iron since I leave it outside on the concrete and work with no shoes!

[tvfixer007]

Re: LG 55LV5500-UA no picture or sound

I found a bad cap in the attached image. Cap reads 1.5-1.8 ohms in circuit and out of circuit. The other cap next it read the same until the bad one was removed. Which was quite difficult to remove but finally got it out.

Other image is for whatever reason. I stepped on my soldering iron since I leave it outside on the concrete and work with no shoes!

For some reason the first image never attached.

[tvfixer007]

Re: LG 55LV5500-UA no picture or sound

Want to update that I repaired my 55LW5600 which had a similar issue to OP's TV. Mosfet burned out. Also a shorted cap on the t-con board. I ordered the new mosfet from arrow electronics, and removed the shorted cap from the t-con board. Powered it up and the t-con board works without the cap for testing purposes.

[ivpavel]

Re: LG 55LV5500-UA no picture or sound

Hey guys I have the same LG (55LV5500-UA) with a slightly different issue. What happens is when the tv is plugged in only the light for the power wil be on and when you turn the tv on the light changes but no back light at all. I poped the back of the tv open measured the power to back light seems good what I have found though no power whatsoever at the fuse on the T-con Board. I have checked the connector from power supply to mother board all voltages and grounds are there. Any thoughts would be appreciated. I suspect the main board but want to see if anyone got anything similar before throwing 80+$ into a board or posibly just fix it myself