LG 60PZ750-UG Powers Off

[cgpastirik]

Hello everyone,
I am stumped, this television started turning itself off after about 20 minutes. I suspect something is overheating though I can't seem to find where. I can turn it back on but then it will shut down again. The caps appear normal no blistering or leakage. I suspect that the issue I am having maybe on the y or z sus board but have no idea what to check or measure. There are some pots on each board y/z but i haven't messed with them.
Anyone that may be able to help I appreciate it it greatly,

Thanks in advance

[Hamie]

Re: LG 60PZ750-UG Powers Off

pictures?

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Pictures attached.
If more detail is needed let me know, Thanks

[Hamie]

Re: LG 60PZ750-UG Powers Off

Read post #12 in this thread.

https://www.badcaps.net/forum/showthread.php?t=50808

Do the test pattern jumper on your model the board should be the same as it's pretty much the same tv.

Run test patterns, let us know if the fault still occurs.

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Thanks for the help, it ran the test patterns for about 10 - 15 minutes and then shut off

[Hamie]

Re: LG 60PZ750-UG Powers Off

Ok to completely rule out the mainboard
Disconnect the cable that connected the power supply to the mainboard and with a piece of wire connect 5vstby to RL-ON

Like this:



Now plug in the tv, the tv will start automatically and start to cycle through test patterns.
Does the fault still occur?

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

30+ minutes without shutting down. I will let it continue. If this turns out to be on the mainboard, is it a simple component R&R?

[Hamie]

Re: LG 60PZ750-UG Powers Off

Just let it run.
Need to be absolutely positive.


Possibly cracked solder under the CPU, Or corrupt data EEPROM.
The mainboard sends the signal RL-ON to the power supply. If it stops sending then the tv will shut down.

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Thanks Hamie, well it has been running the test pattern overnight without issue. I await your next step.

Thanks

[Alastair E]

Re: LG 60PZ750-UG Powers Off

Sounds to me, The Mainboard's faulty....

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Thanks Alastair E, That is what I had been thinking but not sure if the path has another check. Can I force an EEPROM load? I can pull the board and put it under a scope at work looking for cold solder, if it is a bga issue I will just browse the web for a replacement board...

Hoping there is another step/issue from Hamie though, I am about ease and "lets try this" hahahah

Thanks for the help

[Hamie]

Re: LG 60PZ750-UG Powers Off

Try heating and parts of the board with a heat gun or hair dryer.
If heating a certain area shuts the tv down instantly then use freeze spray and see if freezing it keeps it on.

Main boards are difficult to trouble shoot as there are no schematics.
Some parts are preprogrammed so even if you do know what's causing the fault you would need to programme a blank IC before installing it.

Download the latest firmware.

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Thank you,
On the firmware I have the latest installed, I thought I could just reinstall from a USB drive, but it tells me no update needed. Can I force the reinstall?
Thanks

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Alright new (used) power supply, brand new through Sears main board.... TV still shuts down after warming up. Any Idea where to go next? about 300.00 in at this point still cheaper than a new equivalent.

Thanks for help in advance

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Alright new (used) power supply, brand new through Sears main board.... TV still shuts down after warming up. Any Idea where to go next? about 300.00 in at this point still cheaper than a new equivalent.

Thanks for help in advance

Anyone? I have run out of idea..
Thank you

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

not to rain on anyone's parade, but after going through the schematic, this is beginning to look more like a YSUS issue. .

If any one is familiar with an adjustment, replacement or other please chime in. I will update as I figure out more.

Also I located a Service manual for this model with very nice schematics. PDF format should anyone need it.

Thanks



Experience: 20+ year Electrical Engineering Technician

[tom66]

Re: LG 60PZ750-UG Powers Off

If the set ran overnight with the test patterns on it's not the Y-sus or other boards, as the test patterns are pretty much a full on stress test...
There is a very small chance the power board is causing this if the low voltage rails are not well regulated, check if they are stable while the set runs.
Also try the heating idea starting around CPUs - not impossible you got a bad board

[cgpastirik]

Re: LG 60PZ750-UG Powers Off

Thanks Tom, I will have to work that out tomorrow, I will let you know. And yes I agree now having gone in feet first with this think, I have ruled out the YSUS contrary to my last post.....

What role does the ZSUS play in this puzzle?