OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

[miksi]

Hello everybody. I have this 40" LED TV:

JTC LED TV 840CTS
Model #: DVB-PS14007HCAS

Mainboard: CV9202H-NPW
Powersupply: CVB42001
Panel: Samsung LSC400HM06
TCON: Y13_MB7S60TS4LV0.3

But the screen stays black when turned on. Power LED, backlight LEDs and sound works. The mainboard successfully feeds 12v input voltage to the TCON if TV is powered on. But according to the various testpoints on the TCON board, it seems the TCON is unable to produce the other required voltages for the panel.

The attached image shows the TCON board on which i marked interesting testpoints in red. When TV is powered on, these testpoints measure:

VIN_12v = 12v
HVIN_12v = 0
VONE = 0.25v
VOFFE = 0.25v
VSS = 0.56v
VCC_1.8v = 0.01v
VCC_1.15v = 0
VCC_3.3v = 0.75v
AVDD = 0
HAVDD = 0

I also put cyan dots on the picture where I could measure continuity to VIN_12v (even while turned off).

To me it seems ICD1 (SM4154) does get 12v input and is supposed to produce all those other voltages - except 1.8v which will be created by little regulator ICD3 (RT9164A) i guess - but just does not do it.


Can you help me somehow? I am somewhat clueless.

Bye bye!



P.S. To view full image pls use the pdf. I had to export the image as PDF because of the attachment limit, sorry!

[dick_barton]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

The SM4154 does indeed appear to be a volage regulator but I cannot find any information on it other than it is available to purchase from China.

[budm]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

one of those integrated T-CON, I would check the resistance between the two legs of the MLCC (Multi Layer Ceramic Capacitor, the Tan color rectangular caps)) to see if any of them are shorted.

[miksi]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

one of those integrated T-CON, I would check the resistance between the two legs of the MLCC (Multi Layer Ceramic Capacitor, the Tan color rectangular caps)) to see if any of them are shorted.

I measured the resistance of all caps on the TCON (in circuit) and got results ranging between mega-Ohms and zero Ohms. I guess the next step is to unsolder the cap measuring 0 Ohms and test out-circuit. I attached a picture showing the CT27 cap measuring 0 Ohm in circuit and a weird region of unnamed cap-like components to its right where several measure 220 Ohms and 0 Ohms as well. Some are of slight darker color, maybe intentional "bridges" or something like that?

[budm]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Well I think you are on the right path since it the cap should not show 0 Ohms, so it is the cap or the parts that the caps are connected in parallel with is bad.

[ReeceyBurger123]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Ahh more Samsung cheap junk panels failing ! I would probably say one of the tab bond drivers is shorted, but you should check them caps out of circuit.

[miksi]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

I unsoldered the CT27 cap, both its pads still short to ground. weird stuff (for me).
Here is a animated GIF image to show the backside of the area.

[anoop218]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

@miksi did you find any solution for the problem

i have the same t-con board and half my screen is working .

[anoop218]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

any solution or were you able to Revive your tv

[miksi]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Hi, no it is still sitting on my bench xD
But if half you screen is working at least there is hope, i guess! Sounds to me like just a loose connection of one flatflex etc.

[Davi.p]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Hi, i have a Panasonic with a similar issue, in your board QD1 on the left is a transistor switch that feeds power to SM4154 & the switching dc-dc stages, when you plug AC cord probably you get a flash of some tensions where you have measured 0v or near 0v in your post1 list. This is because there's a short somewhere and SM4154 switches itself off by QD1, you have to test first the power diodes in circuit, if them are ok you can feed external power to each output stage (without AC cord in) like a 12v to the AVDD before the diode, 12v to the VON before the diode, -5v to the VOFF output, 1,8v - 1,15v - 3,3v to the respective to see if something gets smoke so you know the shorted part, if no smoke or too high warm SM4154 has probably to be changed.

[vinceroger69]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

@miksi did you find any solution for the problem

i have the same t-con board and half my screen is working .

if half your screen is working you may have a shorted smd capacitor on the panel pcb on the side that is not working so maybe test all the smd capacitors on the bad side of the lcd panel

[Davi.p]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

I was referring to miksi, for anoop the first to check for me is the tab bond extern to the faulty side.

[anoop218]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

I was referring to miksi, for anoop the first to check for me is the tab bond extern to the faulty side.

thank you davi

yes measurred some voltages on the board and i can see all the voltages there mentioned by miksi

i think the cof ic is faulty or do you have some other suggestion

[anoop218]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

please have a look at the attachment

[Davi.p]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

When i say "for anoop the first to check for me is the tab bond extern to the faulty side." i mean you have to touch the outer flat cable to the panel and see if the image rebuilds, your last photo is unuseful if you don't show which is the correct video source.

[inkub]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Hi.

Please read SPI FLASH 25Q64.

BR

[anoop218]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Hi.

Please read SPI FLASH 25Q64.

BR

what do you mean , how to do it

[ayhan yılmaz]

help JTC LED TV 840CTS 25Q32 flash dump

JTC LED TV
jtc main bort: cv9202h-b39
panel :ls400hm06a 1353y01332
eprom flash:25Q32
lol 25Q32 eproom flash cast me this tv flash necessary help:ıslık:

[lordmario40]

Re: OEM TV: black screen, backlight OK, sound OK, no voltages on TCON

Hello my name is Stanciu Marius I am from Romania ... Electronics being a hobby for me, I have a Thomson 40FU3255 tv.
With T-CON: Y13_MB7S60TS4LV0.3
CD8 Short circuit
CD7 ok 10 uF
CD6 ok 10 uF
So an over voltage problem on this T-CON
I hope to repair it ... a nice day to have ... All good in Romania!
Facebook Stanciu Marius