LG50 PA6500 Plasma no pic/sound

[Anh116]

Hi,

I have a LG50PA6500 that I need some advice with. The set has no picture or sound and does not respond to the remote or the control buttons. On the front of the set the standby light stays red and on the back there are a couple of other lights. On the main board there is another red light and on the logic board there is a green flashing light.

I have tested the outputs from the PSU board to the main board to determine if the PSU is at fault. The results I got are listed below in the same sequence they can be seen on the guide next to the plug. Can someone please tell me if these measured voltages are correct?

M_ON 3.342V AUTO GND 0.006V
RL_ON 2.561V AC DET 4.165V
STBY 5.196V STBY 5.196V
GND 0.02V GND 0.02V
GND 0.02V GND 0.02V
5.2 5.192v ERR DET 3.855v
5.2 5.192v 5.2 5.192V
GND 0.02V GND 0.02V
17 17.04V 17 17.04V

Any advice would be welcome.
Thanks,

Anthony.

[chrismurphy]

Re: LG50 PA6500 Plasma no pic/sound

These sets had a tab issue on the top most panel flex
check for a bubble or split on the panel flex before you go any further ,because if the flex is damaged the tv will be a write off
do this by removing the top buffer board
Also check the top buffer chip or shorts
If you have a shorted chip you will need to replace the ysus ,both buffers ,and this will be uneconomical
If interested i have one of these sets working with sound ,but with faulty buffer boards
how to test buffer boards
https://www.youtube.com/watch?v=51SZsfH60EY

[chrismurphy]

Re: LG50 PA6500 Plasma no pic/sound

do you have any power to both ysus and zsus boards ?
Check the fuse on the LHS ysus board and the fuse on the RHS xsus board ,both these are small yellow fuses marked fuse.

[Anh116]

Re: LG50 PA6500 Plasma no pic/sound

Hi Chris, Thanks for the reply.

I've had a look at all the flexes going into the buffer board and they all seem good. I've also tested the buffer boards for shorts by running a meter probe along the connectors and checking for any shorts to ground. The Y-sus does make alot of noise when it is powered up though. Is this normal?

[Anh116]

Re: LG50 PA6500 Plasma no pic/sound

I've tested with a meter that there is power to the z-sus and y-sus boards via the plugs.
I'll double check the fuses.

[Hamie]

Re: LG50 PA6500 Plasma no pic/sound

On your control board

Ie: this one.




Put a wire jumper between the two holes marked ext auto gen.

Here:



Unplug the LVDS cable to main board.

Plug in the TV and if you get test patterns on screen you have a faulty mainboard.

[Anh116]

Re: LG50 PA6500 Plasma no pic/sound

Hi,

I connected the two holes you mention with a jumper cable but got nothing on the screen.

I have also tested the fuses on the y-sys and z-sys boards along with the PSU board and all the fuses seem ok. The voltages are recorded below.

Y-sus. 16.4v
Z-sus. 55v
PSU top 140v
PSU bottom 240v

Are these the correct readings?

[newtothis]

Re: LG50 PA6500 Plasma no pic/sound

Hi,

I connected the two holes you mention with a jumper cable but got nothing on the screen.

I have also tested the fuses on the y-sys and z-sys boards along with the PSU board and all the fuses seem ok. The voltages are recorded below.

Y-sus. 16.4v
Z-sus. 55v
PSU top 140v
PSU bottom 240v

Are these the correct readings?

Firstly before looking at your voltages, You did remove the LDVS cable when you jumpered the control board right?

[chrismurphy]

Re: LG50 PA6500 Plasma no pic/sound

Y-sus 15v ok but check Va should be 205v
check the voltage at the 8 pin plug right/top pin 8 as shown on the board
Your VA z-sus looks ok

[Anh116]

Re: LG50 PA6500 Plasma no pic/sound

Hi,

I jumpered the holes with the ribbon cable to the main board unplugged. Was this the correct one? I got no picture.

[Anh116]

Re: LG50 PA6500 Plasma no pic/sound

I'll double check the vs going to the ysus at pin 8. I'm sure I checked and it's ok. Will let you know.

[vinceroger69]

Re: LG50 PA6500 Plasma no pic/sound

please can you post a picture of the back of your tv showing all the boards etc we can highlite what to disconnect etc and test

[Anh116]

Re: LG50 PA6500 Plasma no pic/sound

Picture of the back of set.