BOE HV650QUB-F70 TCON issue - VGH AVDD HAVDD no voltage - caps seem ok

[cagri]

I have an Arcelik TV with BOE HV650QUB-F70 TCON board, but I think there's an issue with/around PMIC.
PMIC: iML8940

There is backlight and sound, but no picture. I watched a YouTube video and turned it off, half an hour later it was dead.

Input 12v, fuse ok
DVDD1V2 = 1.2v
DVDD1V8 = 1.8v
DVDD3V3 = 3.3v
VGL = -7v
**VGH = -0.3v
**VCOM0, AVDD, HAVDD = 0v
SWBK1 = 3.3v
SW1 = 12v

VGH to GND resistance is 500kohm as expected

Readings are same after I disconnected the two cables from TCON to panel

As far as I could, and quickly check,
No capacitors are shorted, only one capacitor has no short side to GND (capacitance reading is fine though)
Inductors' resistances seem okay
Diodes seem okay
Resistors seem okay

VGH etc. points each are short to at least one of PMIC pins, and VGL is correct so I don't think it's a faulty PCB connection from PMIC.
LD1117AG-AD regulator gnd iirc -0.6v, vin 3.3v, vout 1.8v, R1 (was in datasheet example) is 280ohm, R2 is 137ohm. vout matches the expectation

I couldn't see any shorts or faulty components, except maybe PMIC is faulty. I'm not very experienced in electronics and I wasn't able to find much details for that PMIC unfortunately.
But, VGL voltage is correct and thermal image shows PMIC has some heat. as I'm unsure how it works, I'm thinking maybe a resistor or capacitor for PMIC input values is faulty. I checked a lot of times (while they were still soldered, except diodes) and it seems to be fine.

I'm attaching TCON datasheet, some pictures of it, and thermal images.
In thermal image you can see processor is "hot", regulator is "hot", the bottom inductor is a bit hot. PMIC and inductor in middle is just a bit hot. So I'm thinking the issue is around the inductor/PMIC area as I expected more heat there.
(note that "hot" = 40 C)

Is there anything else I can troubleshoot or try? I wanted to check the transistors but my multimeter doesn't have transistor mode and I'm unsure what should the values be so I couldn't.

I've wasted so much time on this, it's not about the TV anymore, it's gotten personal lol

I apologize if I forgot or mistyped anything since I've been working on this for 12 straight hours, and thanks so much in advance

[nomoresonys]

Re: BOE HV650QUB-F70 TCON issue - VGH AVDD HAVDD no voltage - caps seem ok

"only one capacitor has no short side to GND" If you are sure that one is a capacitor then I think this is part of the problem, can not recall a cap not having connection to ground and the board be functional. What do you get on the ohm scale for that cap? also test it in ohm with meter lead on both ends of cap, also look the cap over very closely some times you will see a hairline crack on bad ones but a cap not reading correctly can point to a problem other than that cap.

[cagri]

Re: BOE HV650QUB-F70 TCON issue - VGH AVDD HAVDD no voltage - caps seem ok

"only one capacitor has no short side to GND" If you are sure that one is a capacitor then I think this is part of the problem, can not recall a cap not having connection to ground and the board be functional. What do you get on the ohm scale for that cap? also test it in ohm with meter lead on both ends of cap, also look the cap over very closely some times you will see a hairline crack on bad ones but a cap not reading correctly can point to a problem other than that cap.

hi, thanks for your reply
i desoldered it and it reads 516 nF
on the board from ground to one end it's 1m-ish, other end 0.8m-ish, capacitor resistance reading changes between 2m ohm to 300kohm
I've also noticed there are a bunch of tiny similar capacitors near the processor and they don't have a short to GND as well, there's a few hundred kohms resistance to GND.

[cagri]

Re: BOE HV650QUB-F70 TCON issue - VGH AVDD HAVDD no voltage - caps seem ok

hey guys, I fixed it by baking tcon card in the oven! it works now! I've ordered a replacement tcon since i don't think it'll work for too long.

[nomoresonys]

Re: BOE HV650QUB-F70 TCON issue - VGH AVDD HAVDD no voltage - caps seem ok

Good work, yes the oven reflows usually don't last very long.