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TheWraith 07-17-2013 04:42 PM

Insignia NS-L42Q-10A won't power up
Trying to fix this for a friend who doesn't have the cash to throw at the GEEK squad to get it fixed.

-Red Standby Light on.

-No response when power button is pressed. No change of any kind. Standby light stays red.

-Got it to turn on once when I was probing for voltages with my Oscope and hitting the power button simultaneously. The problems vanished for a short while and it would turn off and on fine, then it went back to not powering on. Duplicated the same scenario and no dice.

What I know/think:
-Contrary to the Geek Squad's diagnosis, the power supply board seems to be in working order, from what I can tell. All voltages present (even before being powered on when tv doesn't work). Backlight comes on when I tie the on/off pin high, so no issues with the backlight or inverters.

-The Power On signal is High(5v) as soon as you plug in the AC, when the tv will not work. This signal, is provided by the main board, and is apparently stuck on at power up when the tv is not functioning. I am almost certain something on the main board is bad.

-Did a quick cap check with an ESR meter. Have a couple 100uF caps on the main board that I'm going to change, but they are not really bad, just at the hairy edge of being ok...(i.e. an ESR of .30-.32 when my meter's chart says .32 max).

I was hopeful that someone here has had experience with a similar issue and could point me in the right direction. I am trying my best to keep the cost of the repair to a minimum. This guy does alot of volunteering and charity work. He helps others, so I want to help him. I was thinking of maybe trying to reflow U401, the main processor, as it is a BGA.


TheWraith 07-20-2013 07:12 AM

Re: Insignia NS-L42Q-10A won't power up
At plugin does the power board 'start-up' momentarily as a test or something?

I changed those few caps to no avail. The processor has a heat sink mounted with thermal adhesive, I was going to try and reflow all of the bga's, but am hesitant to try and remove the heatsink for fear of physical damage. Anyone have any suggestions on this one? I am at a loss, and the main board for this particular model seems to be out of stock alot of places. I don't want to spend a fortune on fixing it... Any help would be appreciated.

capkid 07-20-2013 01:07 PM

Re: Insignia NS-L42Q-10A won't power up
I'm not sure how much you're looking to spend to replace the main board (if that is indeed the point of failure), but Tri-State Module may have it. It looks like there are several different main boards for this TV - not sure if they're interchangeable:

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