Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

[jason123]

Hello,
Help is much appreciated as I don't have any experience with this model TV.

Picked it up and it was smoking in the back when powered.
Open opening the LED Driver board was charred (see last photo.)

I noticed some blown caps on the Power board as well.

Replaced the LED driver board, and bad caps on Power supply.

Voltages on CN301 (upper power supply connector to LED driver board)
X000017 - All 24.39V
GND - 0.001
OD - 0.015
VSNS - 0.009 (does that imply bad backlight or bad LED Driver?)



Voltages on CN201 (Lower power supply connector to main board)
T CON_ON - 0 goes to 0.0019 when powered on
12V TCON - 0 V
+12VS - 12.53 V
GND - 0.001

12V-AU - 12.51 V
PS-ON - 5.08 V
AC-DET 3.8V

On the Power supply connector (CN202) that goes to the TCON, I don't get any 12V for T CON. Should this be always present, or is turned on by the main board with T CON_ON (Pin 15 of CN201 that is currently almost 0V)?

Any ideas where I go next? Not sure why TCON is not getting power. Main board is responsive to remote and push button.
Thanks

[dick_barton]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

On your last photo you have two major burn ups that are highly likely the issue.

https://tinyurl.com/y6phzbpz

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

On your last photo you have two major burn ups that are highly likely the issue.

https://tinyurl.com/y6phzbpz

Yes, the last picture is the LED driver card that was inside the TV when I got it.

That was replaced as you see in the first photo.

[dick_barton]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Missed the fact that it had been replaced.
I would be thinking that since this is the led driver board that perhaps some of the leds have gone faulty and caused the original fault. If that was the case then replacing the driver would not have solved the problem. Perhaps there is feed back that without the backights on, do not tuurn on the Tcon. Just my thoughts.

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

makes sense. I would just hate to tear down the panel only to find the LEDs are fine. Know what I mean? there are way too many unlabeled wires to test the LEDs inside the panel, unless you know of a way to do that?
There were some bulging caps on the main board 24V rail that I replaced as well. Not sure if this could have caused or contributed to the failure.

[dick_barton]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

If you disconnect the main board and power up, some sets automatically bring up the backlights.
If that doesn't work then with the main board reconnected can you measure the voltages going to the leds at switch on.

Appears to be 16 strips each with 12 leds.


https://tinyurl.com/yxteq4c3

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Thanks...to be certain i opened up the panel. Every LED Tested and all are good

[dick_barton]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Are they run as 16 individual strips of 12 leds, if so then 3v leds = 36V minimum per strip or if 6v leds 72v minimum per strip?

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

16 strips total, 12 LED per strip, lit in 3 LED cluster. Each strip has 2 power [+] wires and 4 wires of negative [-], one per cluster.

[dick_barton]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

CN301 Pin12 OD. Is this Panel power (On Display?) and if so that also appears to be off.

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Not sure what these signals are. But it is close to zero volts

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Main board?

[budm]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

The LED driver board communicates to the main board directly through that small connector on the LED driver board that goes to the main board, the power supply board supplies the Voltage to run the LED driver board.
I do not about the topology used in this TV, but some TV backlights will not come on if the T-CON is not running.
What happen if you disconnect that cable between LED driver board and the main board?
BTW, boost converter burnt up like that can be due to shorted LED's or shorted circuit inside the panel.
Right now do you even see the backlights flash on for seconds at all when you turn on the TV?
And what happen if you do not have that LED connector in that section that was burnt out connected?

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Hi Budm
Disconnected the cable between main and LED driver. No backlight or picture
I don't see the backlight flash at all.
I disconnected the far right connector from LED driver to panel LEDs. No Change
I disconnected in addition the middle connector from LED driver board to panel LEDs. no change

[Diah]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

on such fire at led driver boards, you may got burned cable too or sockets on the led strips.. testing LED always not only if they lid on ... the most important the build in ziner diode if its open or short .. also it was good when you took the screen apart to check all cable end to end & soldering the sockets.

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Thanks Diah - Wires are not frail or damaged, the connector also has some black from the smoke, it wipes off easily. The inside of the connector / pins are still bright golden color.
I don't believe the issue is the backlight. Seems to point to the Main board, and I see many of these sets with failed boards. But if anyone has other suggestions, I'm all ears.. I'd hate to buy a main board to find it's something else

[Diah]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Thanks Diah - Wires are not frail or damaged, the connector also has some black from the smoke, it wipes off easily. The inside of the connector / pins are still bright golden color.
I don't believe the issue is the backlight. Seems to point to the Main board, and I see many of these sets with failed boards. But if anyone has other suggestions, I'm all ears.. I'd hate to buy a main board to find it's something else

yes its early to say if Mainboards issue and i don't think so too. let say you are sure 100% the BL are fine and there no LED ziner diode open or short..

MB send Power ON .. this signal will be shared with T-CON 12V on PSU. so disconnect every things from PSU and run it as stand alone . check your voltage.

another way... every things in place ....the cable line of T-CON 12V terminated from the socket on PSU and feed it with 12V AU. check your screen and the BL.

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Just to clarify, you would like me to add a jumper wire from 12V AU (Currently has 12.51 V) to 12V T CON pin on the power supply connector CN201?

Do I leave the "T CON_ON" at 0 V as it is?
What do I do with OD pin (On Display??? Not sure if that's true) on CN301 on Power Supply?

[Diah]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

Just to clarify, you would like me to add a jumper wire from 12V AU (Currently has 12.51 V) to 12V T CON pin on the power supply connector CN201?

Do I leave the "T CON_ON" at 0 V as it is?
What do I do with OD pin (On Display??? Not sure if that's true) on CN301 on Power Supply?

what do you mean with OD pin? t.-con On stay in place.. as others only---->

you must take out only the wire of t-con 12V out from the socket and feed it with 12V AU to avoid any miss load if you have 12V T-CON on PSU defect... AU 12V its read now little higher cause no load at circuit. it will be fine

edit you can feed the wire you took out also with other 12V such pins 8 & 9

[jason123]

Re: Vizio P602UI-B3 No Picture or Sound - No TCON Voltage

what do you mean with OD pin? t.-con On stay in place.. as others only---->

you must take out only the wire of t-con 12V out from the socket and feed it with 12V AU to avoid any miss load if you have 12V T-CON on PSU defect... AU 12V its read now little higher cause no load at circuit. it will be fine

edit you can feed the wire you took out also with other 12V such pins 8 & 9

Ok, what am I expecting? I did what you described. Pulled the "12V TCON" wire from the connector, then fed the pin on CN201 (pin 14) to "12V-AU"
No change except now I'm getting 12 V on the small connector that goes from power supply to TCON
Still no backlight