LM270WQ1 SD F1 - iMac 27in A1419 LCD

[Kosti]

Hey Team

I have a display problem and I am trying to isolate the issue on the MAC and suspect its a T-CON board issue

The screen seems to light up but only with blue vertical lines however connecting an external monitor via DP shows up perfectly

The panel is made by LG and has the following details LM270WQ1 SD F1

To buy a replacement is almost the cost of a new MAC and shipping to AUS kills any options along with huge risks of a damage screen once it arrives, so I'm hoping I can narrow it down to a component failure

Below are some shitty pictures I took with my iphone

Panel Display








T-Con Board






I am hoping someone can point me in the right direction to begin the troubleshooting of this panel as I have a sneaking suspicion that the issue is probably relating to the timing board and possibly an IC Regulator or maybe even a few CAPS

With my limited skills, I have briefly touched around the ribbon cables and this made no difference to the image, although these feel very hot to touch the chip in the middle of these ribbon cables. I've also cleaned the LVDS cable a few times and re-seated this with no change to the image.

No other component on the T-Con board feels too warm to touch so I am wondering if anyone has had success in repairing such a LG panel as I find it hard to believe the actual LCD is fried

I have seen some you tube videos of "experts" changing these ribbon cables, with some success however these are Chinese made vidz with no comms or explanations

https://www.youtube.com/watch?v=t36YT7-5GTY

Hoping for guidance and assistance
Thanking you all in advance
PEACE
Kosti

[Elss]

Re: LM270WQ1 SD F1 - iMac 27in A1419 LCD

Hi Kosti

I have the exact same issue and I was wondering if you ever solved your issue?
I have found some similar images online and they all point to an LCD replacement. I have a late 2012 iMac.



Please let me know as I am worried about buying a new LCD for $375 USD and then finding it does not work cause its the graphics card or other

thanks
Elss

[cmg]

Re: LM270WQ1 SD F1 - iMac 27in A1419 LCD

Its almost the same panel as in the HP ZR2740W monitors i have. Mine is LM270WQ1-SDDA. *Perhaps* some chance you could swap the TCON from one of these if you find a broken one on eBay. They are pretty poorly made (not what i was expecting from HP) so you may well see one.

I needed to get spare backlight LEDs and had a real job trying to do so. I dont think you'll be able to buy the TCON unless someone has one from a broken LCD on eBay.

Just because the pic is fine on the external monitor doesnt mean the problem is not in the circuit sending the signal to this panel (i.e. in the Mac).

How about:
- clean the connectors very carefully with contact cleaner or IPA and reseat them
- try freezer spray on the ICs, both on the TCON and those which the ribbon cable connects to in the Mac. To do this - run it up and watch the screen - see if it comes good when you freeze one IC at a time

[Kosti]

Re: LM270WQ1 SD F1 - iMac 27in A1419 LCD

I have not had much success and the TCON board seems like a big job for the hobbyist, and so I will just end up buying an aftermarket screen and selling this POS imac once the screen is replaced.

Never again will I touch these over priced lemons!