Sharp Aquos LC-40UG7252E LCD TV burn in?

[Davi.p]

yes jona, since one of the pmic (the RT chips) shuts down then the rest is shut down also and no heat, i send you a pm..

[jonah1024]

then take the screen apart to check downside if there any leak of liquid... its just 40 no risk at all.

This TV was never wet and stayed always inside. I really don’t know why there is corrosion on that inductor and only there 😵

[jonah1024]

yes jona, since one of the pmic (the RT chips) shuts down then the rest is shut down also and no heat, i send you a pm..

So the shut down happens on the ext PSU because there is no current limiting, and the tv PSU is limited so the pmic don’t shut down?

[lotas]

You have a bunch of test points with voltages on your t-con, and that’s where you need to look for faults (resistance and voltage relative to ground...).

[Diah]

This TV was never wet and stayed always inside. I really don't know why there is corrosion on that inductor and only there 😵

Man, i faced same issue on Hisense 40 panel with integrated T-con like yours... if you search here you will find the threat.. little old... first things i did inspect the screen downside.. when i was sure no issue it had... i fixed it with panel firmware.. this issue happened when the panel driver didn't order LCD cells to discharge.. .

[jonah1024]

You have a bunch of test points with voltages on your t-con, and that's where you need to look for faults (resistance and voltage relative to ground...).

Here is an update with the voltages of the circles test points.

VOFF_-11	-13.5 V
VONE	30.15 V
CPV1-6	3.17 V
STV	0.0078V
SEO_OUT	4.96 V
VCC_3.3V	3.3 V
VCC_F_3.3V	3.3V
VCC_A_1.8V	1.8 V
VCC_B_1.8V	1.767 V
HAVDD	7.00 V
HVIN_12V	12.02 V
AVDD	13.98 V
VCC_1.05V	1.014 V
UH	13.5 V
UL	7.8 V

[jonah1024]

[CONT]
Here are the voltage values:

VOFF_-11	-13.5 V
VONE	30.15 V
CPV1-6	3.17 V
STV	0.0078V
SEO_OUT	4.96 V
VCC_3.3V	3.3 V
VCC_F_3.3V	3.3V
VCC_A_1.8V	1.8 V
VCC_B_1.8V	1.767 V
HAVDD	7.00 V
HVIN_12V	12.02 V
AVDD	13.98 V
VCC_1.05V	1.014 V
UH	13.5 V
UL	7.8 V

[Davi.p]

answer to post 38: yes

Avdd voltage is quite low, it's always on the 15-17v range, as i had already suspected

[Davi.p]

on the left of the.corroded coil you have 4 caps, what voltage there is on those?

[lotas]

answer to post 38: yes

Avdd voltage is quite low, it's always on the 15-17v range, as i had already suspected

VDA = Avdd = Vdda = Vsource = 13 to 20 V
VDA is around 14V~20V and this will depend on the design of the T-con board. The VDA voltage is generated by the DC/DC converter circuits. It is used to power the GAMMA circuits and reach the source driver board.

[jonah1024]

Will measure those caps as soon as I get back home from work.

what about HAVDD, is that ok?

[Davi.p]

havdd is avdd / 2.. anyway let tv to cool down, turn on and fast measure avdd, if it lowers with the heat, that coil or the 4 caps has a problem..

[jonah1024]

havdd is avdd / 2.. anyway let tv to cool down, turn on and fast measure avdd, if it lowers with the heat, that coil or the 4 caps has a problem..

The caps measure 1.5V and dropping to 1.16V gradually and stays there .
The upper side of the inductor is wired on one side to this side of the capacitors. The other side measures 1.8V and dropping to 1.48V

The other rightmost identical inductor measures 12V on both sides and the capacitor row below it measures 14V (AVDD) and are stable


PS. I’ve sketched the connection on the picture attatched.

[Davi.p]

Yes, i fogot that corroded L is for a buck regulator, so not for Avdd, the strangeness is that it seem more correct 1,2v than 1,5, that is probably the vcc for main chip

[jonah1024]

what now? 🥹
Sharp replied today and sent me the latest mainboard firmware. I will attempt firmware upgrade again although I doubt that will fix anything.

[EDIT] Yup, nothing changed. I'm on v4.87 from v4.86

[Davi.p]

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..

[Diah]

what now? 🥹
Sharp replied today and sent me the latest mainboard firmware. I will attempt firmware upgrade again although I doubt that will fix anything.

[EDIT] Yup, nothing changed. I'm on v4.87 from v4.86

what kind of theater of repairing panel LOL..
please upload the complete firmware which sharp send you all files include the .txt one

[jonah1024]

what kind of theater of repairing panel LOL..
please upload the complete firmware which sharp send you all files include the .txt one

I doubt this is a firmware issue.

But this is what they've sent me (it’s v4.87): https://we.tl/t-i9nIJ30OSb
I also asked them what could case that color aberration and they said most likely it’s the LCD glass substrate. But why would it randomly return to normal after 2week of not being used?

It’s frustrating cause I can’t find any similar symptom anywhere online.

You Diah said that your Hisense had a similar problem, can you share how the panel looked in your case?

[Davi.p]

Jona, i think you are a little smart enough to understand this is not a mainboard / software issue,
1) panel stand alone = same fault
2) heat related fault

i'm very sad to read almost every day in this , FOR ME, good site with good technicians these fool ideas...
so please ignore those advices.. i think we are close, i suggested recover oxydated components from the beginning, not much been done until now, only the eprom, it's not so risky task if you have hot air, c'mon let's pass to the action.. maybe i go to vacancy next week, i cannot be always online.. bye.. and good luck..

[jonah1024]

Jona, i think you are a little smart enough to understand this is not a mainboard / software issue,
1) panel stand alone = same fault
2) heat related fault

i'm very sad to read almost every day in this , FOR ME, good site with good technicians these fool ideas...
so please ignore those advices.. i think we are close, i suggested recover oxydated components from the beginning, not much been done until now, only the eprom, it's not so risky task if you have hot air, c'mon let's pass to the action.. maybe i go to vacancy next week, i cannot be always online.. bye.. and good luck..

I really appreciate your help and encouragement. 🙂

I will proceed with unsoldering tonight when I get back home from work. Hopefully with a steady hand 😅

Thanks!