How to fix "vertical lines" on my iMac 27 late 2009

HalelujaH!

FIXED!!!

I got a free 27" IMAC because of this problem! Fix was simple! Boot from MAC osx Snow Leopard CD. Erase and repartition internal hard drive. Install MAC OSX Snow Leopard, then install additional software from folder on install CD. Once install is complete the bars went away!

Presto!

OSX Snow Leopard Install Disk was ordered from Apple for less than $20.00. iMac was donated to local computer recycler that only accepted PCs. So they gave it to me.

Do not upgrade these machines beyond MAVERICKS!

God Bless and God Speed!

Professor out.....TZZZZSSSSSSSSsssssssssssss.

Georg,

I've read that the vertical lines have something to do with the display card not working. My Dh's computer has the same problem and I'm searching the internet to see if there is anyway to be able to replace it. So far I haven't found anything helpful or significant. I don't think it's fixable w/o you having to take it to an Apple store. Probably done like that on purpose. If I were able to find a way to be able to fix it, I know I could probably do it, since I've replaced the hard drive on one of my older iMac's. -Katia

Hello everyone,

since i hadnt gotten a reply soon enough, ive taken this iMac in to my supplier and tested it with a bunch of known-good-parts.

I've swapped the LCD (twice), V-sync Cable, Inverter Board, LVDS cable, even all of these items.

The vertical wavy noisy lines remained visible.

After logically assessing that this cannot be the video-card (digital video artifacts or any other typical GPU related issue generally looks totally different, plus this has a sort of 'analogue-ish' look to it: the lines are like an old CRT-screen that has gone bad, or an old TV that's got bad reception on the coax cable) Ive concluded that it must be the Logicboard, and probably the LVDS connector on the board.

I am pretty darn sure i havent ripped the cable out of the connector when opening up the iMac (i've opened up imacs at least a million times before and know what to watch out for) however, maybe this specific connector had already been played with before and gotten a little sensitive..

just thought i'd let you guys know; i know how darn frustrating it can be to google something that is practically un-google-able (you have to be sort of general in the searchbox, yet specific enough not to get all kinds of bogus results like ads, manuals for decades-old macs, or bulls**t websites) and come up with zero results after spending hours on it.

People need to follow up their questions on here more, and post more in general.

im all for sharing the knowledge, let's keep it up!

oh by the way, in the end, my customer didnt mind the defect and said that she would never even have noticed if i hadnt told her about it.. funny

Have you tried resetting the P-RAM? Try holding down Command-Option-P-R during power up.

Hi there, i've seen this several times on different iMac's (all 27 inch models).

It seems it only happens on the models with a v-sync flatcable. The later models with a "normal" connector and separate wires seems not to be affected.

At the moment i have an iMac with the same vertical lines with the additional problem that the whole screen goes black after a few days. When i pust the power button 2 times (standby and out of standby) the screen appears again. The external monitor is not affected and keeps playing when the internal scheen goes black.

Already did a reflow of the GPU and changed the inverter board but no difference.

Guys I have you ever thought about putting the crappy tape they had placed over the lvds connector !?!

:)

I have the same problem with macbook pro early 2008 15,4 inch 2.5 c2d , the thing is from the OSx !! when i boot from 10.6 , it does that ( vertical shadows from the bottom of the screen about 1 inch thick with 1 inch space between them) when i boot from 10.8.5 , works perfectly !!

And i have to mention that i've tried to install the updates for 10.6 , they are downloaded , but the machine NEVER reboots , it stays frozen , so i have to shut it down from the power button !!!

I have a late 2009 imac with a ATI Radeon HD 4850 and had a similar problem last year. I have it connected to an external monitor and the vertical purple lines appeared on both screens confirming a GPU problem.

The OS only booted in safe mode (pressing shift on start up) not in normal mode.

One of my local Apple dealers sent the iMac to an independent repair shop who reseated the GPU (without replacing it). Overheating can cause the GPU to warp and no longer connect properly to the main board.

There are instructions here on iFixit if you feel up to trying yourself. Make sure you also clean the fans and ventilation ports for obvious reasons.

With an quad core 2.8Ghz i7 it's still a very respectable machine which can run the latest OS and software in 2017 so I've been trying to extend it's life as long as possible.

24" 2009 iMac... EUREKA!!!!

This is a long time since the first post but I found your comments really helpful... thank you.

I previously had the HD renewed, a new fan put in etc. put vertical lines persisted. I ended up buying a new one - from Apple - which I realise now I didn't need to.

After months of fiddling, there is NOTHING wrong with my original Mac. I stripped everything off it and restored to factory settings. I then rebooted (CTRL OPT P R) and (after an overnight reload) hey presto! I'm back to Sierra OS with no lines/distortion. It's been running for 6 hours now and no problems.

It is blatantly an Apple intentional problem or 'fix' just to get us all to ditch our perfectly good Apple products so they can make a bit more money off the faithful! Disgraceful.

I’m suffering with vertical lines, but no hint of an image. Just put dab in optical drive sata imac 21.5 2009. Vsync cable might be damaged but this looks like a more serious problem than just that? Any ideas folks?

Hi folks i have been given one of these iMac’s by a customer, and although there is lines on this, its rather annoying, also i have an adapter that is plugged to a VGA cable to my external monitor but nothing showing up, is there some sort of buttons or process on the keyboard i need to do and press, or should i just sell it up, as scrap. Got a 1TB SSD Drive inside this and i can see images on screen if i drag the mouse in a folder i can move it to the top of my screen and i can see it, but its rather useless right now..thank you i appreciate any help that there may be out there….

I am pretty sure that the source of the problem is the controller board on the back of the lcd panel. It probably degrades with the heat produced by the gpu and cpu. I read pretty much all there is to read on the internet about that problem so my guess is that our lcd panels are fine but if we swapped just the controller board from a known working screen that has no lines, it would work perfectly. If i am right, finding a completely trashed imac on ebay just to use the controller board could be a cheap fix. I found the datasheet of the screen on google by searching for LM270WQ1-SDA2 (iMac Late 2009 i7 2.8). Sadly i am in no way able to understand and pinpoint what could be wrong by reading this but an electronics engineer or technician probably could. It could be a matter of replacing some surface mount capacitors who knows?