LG 47 LM8600 - No Video

[Davi.p]

Re: LG 47 LM8600 - No Video

test C512 , C508 near L505, rectify, L505 maybe is a stepup.
check akso if the micriswitch pins are connected to eprom (the one with yellow paint spot)

[anupkg1985]

Re: LG 47 LM8600 - No Video

test C512 , C508 near L505, rectify, L505 maybe is a stepup.
check akso if the micriswitch pins are connected to eprom (the one with yellow paint spot)

I can read 8.2V on C512 and 11.2V on C508. Also pins 1-4 are connected to GND of that microswitch and 3.2V present on pins 5-8.

[Davi.p]

Re: LG 47 LM8600 - No Video

That 8 v feels out of place for me, let me think..

[budm]

Re: LG 47 LM8600 - No Video

https://www.badcaps.net/forum/attach...0&d=1606335986
There are 4 more switching power supplies, you can see inductors with220 and 6R8 markings, that you need to check. There should be power supply that produce the AVDD boosted Voltage and also minus power supply for VGL, to bad they do not provide marking for Voltage test points.

[anupkg1985]

Re: LG 47 LM8600 - No Video

https://www.badcaps.net/forum/attach...0&d=1606335986
There are 4 more switching power supplies, you can see inductors with220 and 6R8 markings, that you need to check. There should be power supply that produce the AVDD boosted Voltage and also minus power supply for VGL, to bad they do not provide marking for Voltage test points.

Yes I have tested those, could you please find the reading in comment#40. There is a 16.43V on L506 inductor.

[Davi.p]

Re: LG 47 LM8600 - No Video

for the L505 i see also a slight low imput voltage of 11,2 when it have to be 12v, can you test the input v at the fuse?

[anupkg1985]

Re: LG 47 LM8600 - No Video

for the L505 i see also a slight low imput voltage of 11,2 when it have to be 12v, can you test the input v at the fuse?

I'm not able to locate the fuse on the board, however I checked the voltage on each pin of LVDS and max I could get is 11.46V from main board.

[Davi.p]

Re: LG 47 LM8600 - No Video

It seems a bit low, maybe you can test the 12v on psu with a dummy load? Or does you feel heat on the tcon chips?

[anupkg1985]

Re: LG 47 LM8600 - No Video

It seems a bit low, maybe you can test the 12v on psu with a dummy load? Or does you feel heat on the tcon chips?

I'm getting 11.89V on PSU when mainboard connected. There is little heat on t-con chips but I believe it's normal operation.

[Davi.p]

Re: LG 47 LM8600 - No Video

I guess 12v is ok, have you found the missng Vgate high and Vgate low? 27v/ -6v..

[anupkg1985]

Re: LG 47 LM8600 - No Video

I guess 12v is ok, have you found the missng Vgate high and Vgate low? 27v/ -6v..

I could measure 27.7V on C528 and -4.9V on C538 caps, not sure if thats what we are looking for?

[Davi.p]

Re: LG 47 LM8600 - No Video

Yes, the tcon is defenately outputting the right tensions i guess, so no problem with it, even if i don't know what it means and don't think changes some, connect all things , turn on tv and push the tcon button, let see what happens, if nothing i guess there's a problem on the panel, also try all the previous voltages with panel connected. Have you got an eprom programmer?

[anupkg1985]

Re: LG 47 LM8600 - No Video

Yes, the tcon is defenately outputting the right tensions i guess, so no problem with it, even if i don't know what it means and don't think changes some, connect all things , turn on tv and push the tcon button, let see what happens, if nothing i guess there's a problem on the panel, also try all the previous voltages with panel connected. Have you got an eprom programmer?

No I don't have eprom programmer bu can arrange it. What is the further test? Do you think it's worth of giving try with new t-con board or more likely panel it self is bad?

[Davi.p]

Re: LG 47 LM8600 - No Video

try all the previous voltages with panel connected.

[anupkg1985]

Re: LG 47 LM8600 - No Video

try all the previous voltages with panel connected.

There is no change in voltages after connecting panel, still no picture or osd menu.

[Davi.p]

Re: LG 47 LM8600 - No Video

If you can get a CH341A programmer with clip you can easily reprogram the i2c eprom on the tcon, not the flash one near the input, or program it only if the i2c doesn't solve, but it's difficult to find the original dumps. Have you pressed button?

[anupkg1985]

Re: LG 47 LM8600 - No Video

If you can get a CH341A programmer with clip you can easily reprogram the i2c eprom on the tcon, not the flash one near the input, or program it only if the i2c doesn't solve, but it's difficult to find the original dumps. Have you pressed button?

Yes, nothing happens by pressing that button on t-con.

[Diah]

Re: LG 47 LM8600 - No Video

cutting off TX signal to panel always never being T-CON firmware issue. its MHz Freq cut off at the Main T-CON IC.. reasons always 1 of 3 this TX the main boards didn't send it because of BGA or the T-CON Main IC fault ( T-con replace ) and the third damage ( open circuit at the panel )

you did test one ribbon disconnected with video signal, and you got only white half mean reason No 3 out. stay 1 of 2 T-CON replace or MB BGA so easy some time the test will be.

[anupkg1985]

Re: LG 47 LM8600 - No Video

cutting off TX signal to panel always never being T-CON firmware issue. its MHz Freq cut off at the Main T-CON IC.. reasons always 1 of 3 this TX the main boards didn't send it because of BGA or the T-CON Main IC fault ( T-con replace ) and the third damage ( open circuit at the panel )

you did test one ribbon disconnected with video signal, and you got only white half mean reason No 3 out. stay 1 of 2 T-CON replace or MB BGA so easy some time the test will be.

Not sure but it's very confusing for newbie like me. I'm just concerned about the panel, if it's bad then there is no point to invest money in the t-con. Also I saw many videos of solving this issue by baking the main board in oven, do you think I should attempt that? I'm just concerned of damaging main board.

[Davi.p]

Re: LG 47 LM8600 - No Video

On some models a problem to the panel,, can cause the tcon software to set a flag in the eprom that switches off the tcon in protection, but in this case , now i note, the tensions are present so no eprom problem. Now have to test if signals come to tcon, on the lvds rails at the eol resistrs 100 ohm, have to see a tension around 1,3v, if the rail that carries the sync signals is missing i think image is not displayed. This is somehow a rare defect i think. The option of mainboard cpu bad soldering is not impossibile, so a test on the lvds lines maybe can reveal cpu to tcon output.