Insignia NS-LCD26A will power on for a few minutes then shut off

[timbo10184]

I inherited an old LCD TV from a family member and was hoping to repair it. The previous owner complained that it would turn on but only sound would come out for about 20 minutes, then the video was visible. I have never seen the video myself since the unit will power on with the backlight on but then power off randomly a few minutes layer. Because the power button and ccfl lamps work I figure the power supply and inverter are functioning properly. There are no obvious melted boards or swollen caps visible. I tried reseating all connections but no symptom resolution. I can't even see the on screen display to tell what input its on. Any help or advice would be appreciated. I am able to find replacement t-con boards but the main board is sold out everywhere. Any ideas on where the problem would be?

[budm]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

https://www.badcaps.net/forum/showthread.php?t=39740

[timbo10184]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

Sorry for not getting the pictures in the OP

[CapLeaker]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

turn the tv on and see what you get on the v5v test pad on the t-con (on top of the LVDS to the right). To check the main board for video, you would need to check the LVDS cable with an oscilloscope and change the picture all the time (turning the menu on and off). You could try also to heat the main board up and see if that get you further.

[timbo10184]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

thanks for the reply, I do not have an oscilloscope but do have a multimeter and will try to heat the main board to see if reflowing will do the trick. I'm assuming the main processor is under the heat sink and not to the right of the RF unit.

[timbo10184]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

quick update, powered the TV on and put heat gun on over the heat sink the picture came on almost immediately, seriously in about 5 seconds. Letting the board cool over the next 30 minutes to see if it lasts. I've seen other threads and know this is likely only a temporary fix but at least I know its a main board issue.

[nuala]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

I would change c541 and c525 both 47mfd/50v on the power supply board as this is a problem for intermittent power on.

[timbo10184]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

Well the TV was alive....but after putting everything back together it will now just play audio with a blank screen and backlight on, and will still shut off on its own after a few minutes. I am toying with the idea of replacing the main board which is at least part of the problem and maybe the power supply, but would cost about $60. Does anyone have any input on if its worth that? Its a 2007 TV and a cheap 32 inch led can be had for just $40 more now.

[CapLeaker]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

since the heat gun fixed the problem temporary, look at the capacitors... may be a cheap fix. You should be able to recreate this by heating up the caps. Maybe just do a spot at the time.

[nomoresonys]

Re: Insignia NS-LCD26A will power on for a few minutes then shut off

good idea CapLeaker, might just be bad electrolytic thru hole cap/s on the mainboard.