Visio D55U-D1

[jostewcrew]

Hey all, have a visio d55u-d1 i have been working on. I'm officially asking for help at this point as i am out of ideas.

Symptom: Black screen, no backlights. Sound (cant verify atm)

was watching a show, picture cut out, still heard sound....shut down and cant see or hear anything now. forgot which input was on so can no longer verify sound remains although it did before starting to troubleshoot.

I swapped the main board and the led driver board so far...nothing. does anybody have a service manual for this model?

if not, can someone hold my hand through the entire troubleshooting process? im looking to learn and gain knowledge of this brand of tv repair. i have all tools required to troubleshoot and repair when issue is found. i appreciate any consideration on helping me learn. just tell me what to do and perhaps guide me to the answer to retain better.

[jostewcrew]

Re: Visio D55U-D1

Hey all, have a visio d55u-d1 i have been working on. I'm officially asking for help at this point as i am out of ideas.

Symptom: Black screen, no backlights. Sound (cant verify atm)

was watching a show, picture cut out, still heard sound....shut down and cant see or hear anything now. forgot which input was on so can no longer verify sound remains although it did before starting to troubleshoot.

I swapped the main board and the led driver board so far...nothing. does anybody have a service manual for this model?

if not, can someone hold my hand through the entire troubleshooting process? im looking to learn and gain knowledge of this brand of tv repair. i have all tools required to troubleshoot and repair when issue is found. i appreciate any consideration on helping me learn. just tell me what to do and perhaps guide me to the answer to retain better.

For those that are interested, i have troubleshot some and researched...that is why i have replaced the boards that i did. i would like to start from scratch, however, my troubleshooting has lead me back to where the power supply is outputting what it says on the screen print, the mainboard is showing logic as it is turning on the tv and kicking in the high voltage to the power supply and the led driver board. the tcon board is not getting proper voltages. 0.032v when set is on. the cap at the lvds going to the tcon is also .032v when unit is on. this is the new mainboard as well. this is why im scratching my head as i dont know whats pulling it down.

[neilc6]

Re: Visio D55U-D1

With no backlights, you need to verify the mainboard is outputting a BL_ON (sometimes labelled ON/OFF) signal to turn on the backlights. Not sure if this model has BGA failures like the M series.

[nomoresonys]

Re: Visio D55U-D1

If you haven't already, shine a flashlight at the screen, hit menu see if you see the menu or any text on the screen.

[nomoresonys]

Re: Visio D55U-D1

Try unhooking the tcon to panel ribbons, see if you have same voltages for tcon as you have now, can also try unhooking the wifi module see if tv starts up, maybe check the tcon fuse.

[jostewcrew]

Re: Visio D55U-D1

neilc6: the powerboard has on/off that goes to the main board. from the main board it goes to the led driver board. with the set off...the on/off is .014v. when powered on, the on/off is .110v

nomoresonys: did flashlight test...no image. the voltage on the tcon fuse, both sides is .032v. same when the ribbon cables is connected or disconnected. the caps on the main board near the lvds feeding the tcon is also .034v. unplugging the wifi module does not seem to have any affect.

[neilc6]

Re: Visio D55U-D1

neilc6: the powerboard has on/off that goes to the main board. from the main board it goes to the led driver board. with the set off...the on/off is .014v. when powered on, the on/off is .110v

Both your main boards are bad. 0.1V is not a logic high level You can try heating up the processor with a hair dryer before plugging in.

Baking the boards is not a permanent fix though it may work for awhile.

https://www.badcaps.net/forum/showthread.php?t=76708

[nomoresonys]

Re: Visio D55U-D1

Don't know what tests you have done, test number 3 below is a good place to start:

[jostewcrew]

Re: Visio D55U-D1

neilc6: ty for confirming the mainboard. i was suspecting that i recieved a bad new arrival. i had a testboard that would hook up and turn the backlights on with no good image, but it had the unit on at least. but i wasnt 100 percent. i will move in on troubleshooting the main. anyhelp with troubleshooting this board will be appreciated.

on a note for knowledge:

can you explain where that 3.3 on/off is supposed to originate? pb or mb? is it a logic function from mb that enables pb function? any insight is appreciated.

[nomoresonys]

Re: Visio D55U-D1

Mb.

[jostewcrew]

Re: Visio D55U-D1

nomoresonys: ty for your insight as well.

i will troubleshoot the main board compared to the other boards i have and surely i could pinpoint what is not functioning. i will post back with findings. ty all

[budm]

Re: Visio D55U-D1

Can we see good clear pictures of the whole backside of the TV showing how all the boards are connected together?
https://www.shopjimmy.com/catalogsea...=Vizio+D55U-D1
More likely that the BL-ON (ON/OFF) and Dim signals are not routed through the power supply board to the LED driver board, more likely that the BL-ON and Dim control are done directly between main board and the LED driver board. The power supply board is only supplying the running Voltage for the LED driver board.
Try heating with hair dryer as nelic suggested.

[jostewcrew]

Re: Visio D55U-D1

thanks budm: appreciate the effort you were about to partake in... got it narrowed down to the main board once again....with my troubleshooting and the help from everyone here, i am now looking at the main board. the remaining issue now, since the blon originates from the main board...is to find out what in circuit is failing bringing down the mainboard blon to .114 and stopping the 12 v out to the tcon. im all ears and ability if you have any ideas good sir.

the board is : 756TXFCB0QK0240

[budm]

Re: Visio D55U-D1

Read my updated post 12.

[neilc6]

Re: Visio D55U-D1

Those signals come directly from the main processor through the BGA connections. The lead free solder balls crack over time with temperature cycling so they lose connectivity. Proper repair is to reball.

[jostewcrew]

Re: Visio D55U-D1

neilc6: with your insight, i applied some flux and heated the processor manually with a 250c 3 min to 300c 3 min, 350c 3 min profile via my hot air station. this made no difference. im still learning so these temps may not have been sufficient to have any affect?

budm: thank you for the extra confidence backing up neilc6s' suggestion. hard to take one mans word sometimes so that helped.

any suggestions on a better profiling for reflow or perhaps a source of a pin out that i can verify the chip isnt functioning?

[neilc6]

Re: Visio D55U-D1

deleted

[jostewcrew]

Re: Visio D55U-D1

thanks all for the assistance. got a new main board in and sure enough, fires right up. sent the "new" main board back for exchange for this one. it happens right? thanks for the confirmations and assistance.