Sharp Aquos LC-40UG7252E LCD TV burn in?

[Diah]

yours firmware upgrade one... it header to skip over write chip.. you need factory firmware.

[jonah1024]

The logic says the good is at 1,5v, then with the heat resistance rises and voltage drops to a bad value, try unsolder, remove and resolder that coil..

Unsoldered that coil, measured its resistance (<0.4 ohm) then soldered it back. Problem is still there…

[Davi.p]

Have you removed all old solder? I would suspect one or more of those 4 caps.. replacing them all with at least 10uF 10v each, better 50v..

[Davi.p]

We can only suppose that 1,5v is the correct one, since 1,5 is the normal voltage for ddr ram, but no ram is present, main chip usually needs about 1-1,2v, so that 1,5v can be normally 3,3v that is a voltage for COF chips, or 1,8v also for COF, this to tell that COF can be shorted, not completely but unremediable broken..

[jonah1024]

Ok so I unsoldered all the caps and the diode next to the inductor, tested all of them and there is no short. Diode is also ok. I then tried to trace the connection and the caps are directly connected to the VCC 1.05V test pad which measured is about there (~1.02 V).
I've attached a photo with the trace.

Also, The resistance between the caps pad (or in that case the VCC1.05V pad) and ground is about 105 ohms. Is this normal?
Also, VOFF-11V is actually -13V is this normal?

[Davi.p]

you previously said it was at 1,5v when cold, is now the same? was the main ic Samsung heating too much? The vcc_1.05v is connected also to another chip more than the main chip, it would be useful to feed only the 1.05v externally, no other power, and feel the heat on various ic, caps, etc..

[lotas]

Ok so I unsoldered all the caps and the diode next to the inductor, tested all of them and there is no short. Diode is also ok. I then tried to trace the connection and the caps are directly connected to the VCC 1.05V test pad which measured is about there (~1.02 V).
I've attached a photo with the trace.

Also, The resistance between the caps pad (or in that case the VCC1.05V pad) and ground is about 105 ohms. Is this normal?
Also, VOFF-11V is actually -13V is this normal?

Why do you unsolder these components (capacitors, inductor, diode), everything is fine there! 1.05v is the power supply to the processor core and it always has low resistance (it’s not for nothing that such a powerful inductor is used.

[jonah1024]

It's still 1.5V if measured with the ground as chassis, 1.42V if measured with ground on the nearest ground on tcon.
The VCC1.05V pad measures 1.3V at power on and slowly decreases close to 1.05V
Yes, the main Samsung IC heats up as well.

[jonah1024]

Why do you unsolder these components (capacitors, inductor, diode), everything is fine there! 1.05v is the power supply to the processor core and it always has low resistance (it’s not for nothing that such a powerful inductor is used.

I soldered them back, TV is back to square 1.

[Davi.p]

I see you are providing some random measurement values, i suspect your meter battery is not ok..

[jonah1024]

I see you are providing some random measurement values, i suspect your meter battery is not ok..

Hmm what do you mean by random?
I will replace battery as well but all measurements are consistent, are they not?

[Davi.p]

i mean you wrote too much values of the 1.05v rail to be comprehensible

[jonah1024]

i mean you wrote too much values of the 1.05v rail to be comprehensible

I'll try to be less confusing:

• bottom part of Inductor measures 1.8V decreasing to 1.48V stable
• the other part of the inductor (that is also connected to the 4 capacitors) measures 1.43V going down to 1.16V
• this in turn has direct connection with the VCC_1.05V (which measures around 1.3V decreasing to 1.02V)

The voltages differed a bit (by about 0.1V more) If I measured using ground from chassis instead of ground pad on T-con board. That's all

[jonah1024]

New panel symptoms:
It started flickering now.
Main Samsung IC heats up really well as before but freezing it with air can makes the flickering disappear.

I tried doing a better job with the parts I resoldered but those new symptoms are still there.

PS: I noticed that COFS heat up really well too.
Here is video with the new symptom: https://www.youtube.com/watch?v=TvoXVFQhhg0

[Davi.p]

From before the inductor to the main ic load there is a suspicious high v drop, i think that glue around the chip hides a sad secrect and it is not protective

[jonah1024]

That’s sad. I feared you would say that.
This means giving up I guess. 😢

Thank you everyone for the contribution!
I learned a lot even though repair was not successful.

[nomoresonys]

Well if its down to giving up, maybe try a diy reflow, check this thread, some good info about how to and what temperatures to use, and yes I know it might not be the problem but these things can be very tricky and nobody has come up with the perfect answer yet: https://www.badcaps.net/forum/troubl...-no-backlights

[nomoresonys]

I would try a diy reflow on the big chip on the driverboard where it says deno tp3, if no joy, then maybe remove the heatsink of the bga on mainboard and refolw that. Might not be the problem but as someone said before, "I have seen stranger things"

[Diah]

go to this side and ask for firmware early version with panel firmware.

[Davi.p]

is there someone able to reball the main chip? you can give him the tv set for free or some few $