Panasonic TX-65x700 start problem

[perette]

Hello everyone.

A friend of mine has a Panasonic TX-65x700.

Since yesterday it shows the Following symptoms.
Cold start, black screen, backlight works
Restart, blue and black vertical bands ( always the same scheme), sound OK, no osd (see picture)
Next restart, ok image and sound, stable.

It looks like somethingnneeds to be a bit more heated to run properly.

I was thinking to open the back, and heat with an hair drier one board after another to find the faulty one.

Any idea or favorite place to look at.

Thanks for advices.

Jm

[dskall]

Re: Panasonic TX-65x700 start problem

I would start with power board. Look at caps for bulging tops.

[perette]

Re: Panasonic TX-65x700 start problem

hello dskall

Thanks for the advice, I was planning anyway to make a deep inspection.

I can't fond any doc on the net on this TV set, so I don't know if there is a T-Con or any info on the intenrla design.

It's only a 2 years old TV and I guess that rhere is not a lot of fiedback on weaknesses.

Let(s move this way.
I'l do it this week.

Best regards

JM

[Davi.p]

Re: Panasonic TX-65x700 start problem

Problems with the el. capacitors are the past..It's more probably a bga soldering isuue or a dc-dc converter issue on tcon or frc.. post pictures of back with no cover, and each board except the power one, locate each possible dc dc conv. starting with the linears using datasheet, then warm them before turning on and see the image..

[perette]

Re: Panasonic TX-65x700 start problem

Hi Davi

I'll do it this week. The TV is located at my daughter's house.

Agree that caps are less and less a concern. Having a look does not cost a lot.

Pictures will be taken and I have a way to (cautiously) cool down a component with compressed gas duster.
If it's temperature sensitive, then I may be able to locate the bad guy.

Many thanks

Jean Marc

[Davi.p]

Re: Panasonic TX-65x700 start problem

Sorry my confusion, forget about dc dc converters, they suffer the heat... much probably connectors to the screen, second chance bga issue, third chance el. cap. but i would not bet on it..

[perette]

Re: Panasonic TX-65x700 start problem

hello everybody

I've been able to open the beast.
Here are some pictures.

Rapid inspection did not show any big issue, but, on the back of the power board some soldering are clearly damaged.
especially on components on heatsink.

As the problem seems to be heat related, i guess that this can explain symptoms.

I'll renew all "suspect" soldering and let you know the outcome.

Best regards

JM

[dskall]

Re: Panasonic TX-65x700 start problem

Don't think that is the problem. But resoldering can't hurt. Try warming mainboard and see if start up changes.

[perette]

Re: Panasonic TX-65x700 start problem

Hello

Resoldering did not change the problem.

I've made a vidoe of the starup process with the 3 phases.
https://youtu.be/WmgrGgEntKc

Heating the main board did not changed anything.

What i can tell also, is that if I leave the tv off for 15 min, it will go to the 3 restart phase needed to have it working.
If then I just switch it off and restart, then it works immedialtly.

After some minutes off it goes back to the toubled startup.

I'll make a test with the T-CON (heating) to see if it comes from there.

any other test I can make to try to locate the fault ?

Best regards

JM