Insignia NS-50DR620NA18 w/ large vertical lines & no picture

[srs]

I'm not sure what to do next and came here since y'all helped me fix a 50" plasma TV back in 2014, which is still working!

A friend gave me an Insignia NS-50DR620NA18 50" TV that suddenly developed large vertical lines on it. He said he had no idea what might have caused it and has replaced it with a larger TV. He was going to throw it away.

I did not notice any bulged or leaking caps on any board, the voltages produced by the power supply match the voltage that the pins are marked. The backlight leds are working. I have tried cleaning the ribbon cables on the T-CON board with isopropyl alchohol with no changes. I noticed that the mainboard seems to be working as the display changes (more red) when I push the Netflix button on the remote.

I have swapped the T-CON board as well as the mainboard with no changes to failure mode. I tried unpluging the ribbon cables from the T-CON board to the tab bonding board one at a time and the vertical lines stay with the side that is still plugged in, the other side has no picture.

I've lightly pushed on the tab bonding board flex cables and saw no changes in the picture.

Let me know if you would like more/better/different pictures and I will get them for you.

Thanks in advance.

[nomoresonys]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

Looks like you have done a good job testing things, not a lot left, maybe test the little mlc caps on the panel driver boards for shorts or very low ohms.

[srs]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

I'm not certain what caps I'm looking for or the values I should expect to see. I have attached some pics of the tab boards, can you give me some guidance on what I'm looking for? Thanks.

[nomoresonys]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

Those little brown ceramic caps, they have the designator next to them, the ones starting with C are capacitors.

[nomoresonys]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

The big copper pad on the end should be ground for each board, put neg. probe on it, pos. probe on either side of cap one side should show continuity to ground the other should not, can also put a probe on each end of cap and see if it shows a short, can also test in ohm mode with test lead on each end of cap see if it tests very low. These tests done with tv UNPLUGGED from power of course.

[lotas]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

Replace these resistors with 10 Ohm and remove these protective diode assemblies and everything will be fine.
And in vain they bought both the motherboard and t-con.
It's been the exact same problem for a while now. https://www.badcaps.net/forum/showthread.php?t=118195

[srs]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

I unplugged the panel boards from the T-CON and tested all of the caps. Most were over 100kohms, some many megohms, one on each board was 770 ohms - same cap on each board. Does that sound right?

Lotas, thanks for this info. I haven't seen this info yet so I really appreciate you sharing it. I'll have to search for replacement 10 ohm resistors on dead laptops or something and give this a try. No caffeine for me that morning…

Should I put the extra mainboard and T-CON boards on the classifieds here or just put them back on eBay?

[lotas]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

To begin with, carefully remove the diode assemblies (even all 4 pieces are possible), without damaging the board or cables, then look for resistors.

[srs]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

I removed the 2 diodes that you marked in the pictures and it is working correctly now.

Thanks so much for your help!

[lotas]

Re: Insignia NS-50DR620NA18 w/ large vertical lines & no picture

Thanks so much for your help!

Please!