LG 60PV450 - No picture/have sound

[cutmebr0]

First thing, I've read just about everything about this TV on this forum and it's infamous due to it's ZSUS failures and inability to find replacement for it.
Anyways I got this for $30. Been working on it off and on.

The issue is it will turn on, no video but I have sound.
I can hear buzzing in the back on nearly every board, and all heat syncs get warm.
I have tried doing the image test by jumping the points on the control board with and without LVDS cable plugged in, still couldn't get an image to come up.
I do have a blinking green light on the control board.
I don't even get a faint glow panel.
I've also tried unplugging zsus and the TV acts the same.
However unplugging the ysus results in booting off immediately after plugging power in.
All fuses check good.
I've made sure all ribbon cables are plugged in correctly and not crooked or broken.
I've test my VS, VA and 5v coming from PSU and the other end on both boards, and they test good according to the panel sticker.

So far I have sent the ZSUS off to mygoodiefinder in Paris TX to get fixed. He stated he did the following:

Visually it's hard to say, I would have changed the fuse and 6 PF4633 mosfets plus reworked the solder of the 3 large coils, which is the cause of these boards failing. There are 2 small 27 ohm surface mount 2 mm long resisters near each of the mosfets I change, they can be issue, you can look at them for obvious damage it's hard to see it sometimes so I check them with a meter before I put the mosfets in, maybe that is issue dunno maybe a weakened one let go or checked good and really wasn't, I try to be real fussy with them, usually 2 are bad and obvious ~ robert

I took all boards off of the TV for inspection and the only thing that looks suspicious is the coils on the ysus, a joint look a little cracked. I'm going to fix that today and let you know how that ends up.

I also have the following manuals:
50pv450 Schematics and Exploded View
50PV450 Training Manual
60PZ550 Service Manual

I just need a little help. I have to be missing something simple. I'm sorry if I've left anything out, please let me know if I have.

[dick_barton]

Re: LG 60PV450 - No picture/have sound

Have you checked the fuses F101, F102, F103, F104. What voltage do you have across the points (+Vy & -Vy) and also (+Vsc & -Vsc)

[cutmebr0]

Re: LG 60PV450 - No picture/have sound

Have you checked the fuses F101, F102, F103, F104. What voltage do you have across the points (+Vy & -Vy) and also (+Vsc & -Vsc)

I will check today after lunch. I need to search through the manuals I have and find the test points for (+Vy & -Vy) and (+Vsc & -Vsc). I'm mediocre at best with this lol. Think I got lucky on my previous repairs.

[dick_barton]

Re: LG 60PV450 - No picture/have sound

I will check today after lunch. I need to search through the manuals I have and find the test points for (+Vy & -Vy) and (+Vsc & -Vsc). I'm mediocre at best with this lol. Think I got lucky on my previous repairs.

As shown in the attached photo courtesy Shopjimmy

[cutmebr0]

Re: LG 60PV450 - No picture/have sound

As shown in the attached photo courtesy Shopjimmy

You are amazing. Thank you for that. I'll report back at lunch.

[tw2005]

Re: LG 60PV450 - No picture/have sound

Won't be surprised if it's just the cracked joints on the coils.

Just did my first 60PV250 same boards, was told intermiitent loss of picture with sound. By the time I got it, it would not even do that. Bad coilson the zsus and ysus, ysus had failed transistors likely due to continuing to run it with the faulty joints.

Got lucky and just replaced the bad transistors, reflowed the coils and running fine.

good luck with it.

[cutmebr0]

Re: LG 60PV450 - No picture/have sound

As shown in the attached photo courtesy Shopjimmy

So I went to go test and realized I didn't know how to test that. Do I place prongs on each point or just one? Sorry if that's a stupid question.
I somehow bridged the gap between the heatsink and the test point and scared myself a bit, plus I was watching my kids so I couldn't really focus and decided to wait til my wife is home to try and test it correctly lol.
I did check the fuses and they are good.

[cutmebr0]

Re: LG 60PV450 - No picture/have sound

Won't be surprised if it's just the cracked joints on the coils.

Just did my first 60PV250 same boards, was told intermiitent loss of picture with sound. By the time I got it, it would not even do that. Bad coilson the zsus and ysus, ysus had failed transistors likely due to continuing to run it with the faulty joints.

Got lucky and just replaced the bad transistors, reflowed the coils and running fine.

good luck with it.

So I'm no pro at this, MOSFETS are the transistors you're talking about right? If so I I'll replace those if you think it's worth a shot!

[dick_barton]

Re: LG 60PV450 - No picture/have sound

So I went to go test and realized I didn't know how to test that. Do I place prongs on each point or just one? Sorry if that's a stupid question.
I somehow bridged the gap between the heatsink and the test point and scared myself a bit, plus I was watching my kids so I couldn't really focus and decided to wait til my wife is home to try and test it correctly lol.
I did check the fuses and they are good.

With your meter set to volts >200v place black probe on the "-" point and the red lead on the "+" point. So black on "-Vsc" and red on "+Vsc" and same procedure for Vy

To test mosfets look on Youtube which has plenty of videos on how.

[cutmebr0]

Re: LG 60PV450 - No picture/have sound

With your meter set to volts >200v place black probe on the "-" point and the red lead on the "+" point. So black on "-Vsc" and red on "+Vsc" and same procedure for Vy

To test mosfets look on Youtube which has plenty of videos on how.

Update here:
When testing Vy and Vsc it jumps all around and doesn't stay anywhere near stable. I'll have to take a video of my meter when it bounces back and forth.