LG 60Pv450 help!

[nasium]

Hi all…..new member here and I need help with sound only on my LG 60PV450. First thing I did was check all the voltages on the power supply and they all checked out good. Then I checked out all the fuses and the FS104 2A 125v fuse was blown on the Y-sus. I have good soldering skills but decided to order a new one on Ebay. Before installing it I checked all the fuses and they were all ok.
After installing the new Y-sus board, I turned on the TV and nothing but sound and the FS104 fuse burned out again. Back to square one.
Learned quite a bit from Tom66 and others, I have attached some pictures with voltage values.
Va 55v
Vs 202v
Vy 180v on Y-sus
Vsc 19.5v on Y-sus
Vzb 8.4v on Z-sus
Zbias 1.8v on Z-sus ribbon cable
Sus-up 198v on Z-sus ribbon cable
Pin 1,2 of Z-sus ribbon cable should be 18V and it's 0
Pin 1,2 of Y-sus ribbon cable should 15v and it's 0.
I tried jumping the logic board cable and pulling the ribbon cable without anything displayed.
Any help would be much appreciated!

[audiofreak19]

Re: LG 60Pv450 help!

Probably an issue with one of the buffer boards

[tom66]

Re: LG 60Pv450 help!

Would agree with buffers being a possibility, to test it you can remove the buffers and see if Vsc returns to approx 150V.

[nasium]

Re: LG 60Pv450 help!

So I disconnected the buffer boards and the vsc voltage started at 90v and slowly worked up to 152 volts. Not sure why the vy voltage is -180 negative even though the probes are on the + and - respectively.

[tom66]

Re: LG 60Pv450 help!

-Vy is supposed to test negative, so that is OK. You have a bad buffer board. You can try the TV with only one board at a time you may get half a picture on the screen.

This set should run with a picture if the top is out but bottom is still installed.

[nasium]

Re: LG 60Pv450 help!

Sounds good.......I'll give that a try tonight. Are those normal voltages for the Z-sus board? Or are they also affected by the bad buffer board.

[tom66]

Re: LG 60Pv450 help!

Hmm, that Zbias is low too. Try with the buffer out, perhaps the control board is detecting an error and turning that off.

[nasium]

Re: LG 60Pv450 help!

With top buffer board connected the vsc 167 volts. Decided to check the vzb on the zsus and got 5v. No half picture with this setup :-(

With the bottom buffer board connected the vsc voltage was a solid 20.4 volts. Checked the vzb on the zsus with this setup and it was a solid 6.7 volts. No half picture with this setup.

The -Vy never changed with either scenario solid -180v.

Reminder the fs104 fuse is blown with all this testing on the ysus.

Many thanks!

[nasium]

Re: LG 60Pv450 help!

Working on the zbus for low voltage problem... I detached the buffer board. In the process of screwing down the board I noticed a little spark as I screwed in the bottom middle screw and then then a pop sound and a spark came from the top left heat sink. Going to need to get a Zbus.

[tom66]

Re: LG 60Pv450 help!

I think you have Y-sus and Z-sus faults...

[Alastair E]

Re: LG 60Pv450 help!

Working on the zbus for low voltage problem... I detached the buffer board. In the process of screwing down the board I noticed a little spark as I screwed in the bottom middle screw and then then a pop sound and a spark came from the top left heat sink. Going to need to get a Zbus.

Were you doing this --With the set powered up...?

Should Never disconnect/reconnect/remove/replace/ Anything--Including mounting-screws--With the set powered up!

When doing any removal/replacement--Unplug from mains, and Leave for 5 minutes before doing anything at all. This time allows charged up caps to dissipate and prevent any possible issues....

As it stands, sounds like you need to replace Both 'Sus boards' and the buffers!

[nasium]

Re: LG 60Pv450 help!

Were you doing this --With the set powered up...?

Should Never disconnect/reconnect/remove/replace/ Anything--Including mounting-screws--With the set powered up!

When doing any removal/replacement--Unplug from mains, and Leave for 5 minutes before doing anything at all. This time allows charged up caps to dissipate and prevent any possible issues....

As it stands, sounds like you need to replace Both 'Sus boards' and the buffers!

Yeah it was powered down but I should have waited the 5 minutes as you say.

[nasium]

Re: LG 60Pv450 help!

I think you have Y-sus and Z-sus faults...

What are your thoughts on the buffer boards with the voltage results I got?

Many thanks?