Vertical line on iMac after opening it for upgrade

Hi Forums,

I have a 2013 iMac 21.5" that I recently opened to replace the HD with a SSD. I've done this before on another mac without problem. On this machine, the process went smoothly but when I reassembled the system I now have a vertical line on the display. On the bright side the rest of the computer and SSD work fine. On the bad side I have this persistent display issue. The vertical line seems different than what most others report when I google this problem. Most people talk about a defect in some iMacs (due to a bad capacitor) that cause thin 1-pixel wide vertical lines. Mine is different. It looks to be about 20 pixels wide of dark pixels and one center pixel that's lit. The lines run from the top to the bottom of the display. The pixels involved do not display what is asked of them. That is while the rest of the display shows osx and whatever it's supposed to, the involved pixels always show what's in the images below.

See attached photos. Sorry about the quality, it’s hard to photograph.

Since I only replaced the HD I only really touched the two cables that go between the display and the main-board. There are two cables. One that looks like a data cable (with lots of pins) and one that looks like a power cable (with 8 wires).

I tried opening the system and reseating the cables a few times but the line persists. I looked carefully at the pins and cables and they seem fine.

So my questions are 1) any thoughts on what might have happened and ideas on how to fix. 2) am I correct in my assessment of the two display cables? what are each of their functions? It looks like you can buy a replacement cable for the ‘data’ cable (about $30) but the other (8 wire) cable is a bit more tricky. 3) anyone else have this problem after opening an iMac?

Thanks
Ryan

My "guess" is that you inadvertently damaged one of those cables upon disassembly. Probably a good idea to replace both of them.

cables

Thanks chscag. The data cable (which I now know is an LVDS cable) is "easy" to replace and you can get them for about $30, but the other cable is not really replaceable (I don't think). While one end is the end I disconnected/reconnected, the other end splits and goes into the display itself and it doesn't look replaceable.

I'm going to see what others say too.

The LVDS cable or the logic board connector is more likely damaged, but try reseating it first. Make sure the clamp bar is down and in place. Hopefully you tested the iMac before fixing the LCD back in position with new VHB strips.

techiesteve said:

The LVDS cable or the logic board connector is more likely damaged, but try reseating it first. Make sure the clamp bar is down and in place. Hopefully you tested the iMac before fixing the LCD back in position with new VHB strips.

Click to expand...

Thanks techiesteve. Yes, I'm not reapplying the tape until after I get this nailed down. I've tried reseating both cables several times without success and I made sure the clamp bar was down and in place. I looked at both cables and their connectors with a magnifying glass and couldn't see any damage (eg. bent pins or obvious damage). I tried cleaning both by blowing on them (thinking that maybe there was dust somewhere) but no luck. I've ordered a LVDS cable so hopefully the cable just got damaged. The frustrating thing is that nothing obvious happened during the upgrade. That is, I didn't knock, drop, hit, or force anything. Hard to believe the system is so fragile.

I may also try to remove the LVDS cable (from both ends) and then use a continuity tester to see if all the pins go through.

Would any hardware diagnostic programs tell me if the logic board connector is damaged? I assume the logic board connector is one of the ends the LVDS connects to. Is is on the 'computer' side or the 'display' side?

Thanks

I've disconnected a refitted the LVDS cable no end of times at work, never with any problems. I always pull the black plastic tab away and upwards to release the clamp, then disconnect.

Logically the problem should be the LVDS cable, as that was removed during the upgrade, and hopefully it will be. I have seen similar faults to yours caused by the LCD, but based upon what you have done it shouldn't be. Let us know how you get on.

techiesteve said:

Logically the problem should be the LVDS cable, as that was removed during the upgrade, and hopefully it will be. I have seen similar faults to yours caused by the LCD, but based upon what you have done it shouldn't be. Let us know how you get on.

Click to expand...

Thanks Steve. Your logic makes sense. I'll keep my fingers crossed.

I'll post an update later this week (when the cable comes).

Hi guys,
Well, the new LVDS cable came and I replaced it. No luck. Same dead columns with the new cable. I tried reseating the cable a few times and it's the same every time. Any thoughts on what to try next? Should I attempt to replace the LCD? It looks like they're about $240. Is it worth trying this? Note that an externally connected display is fine which makes me think that the onboard graphics card is fine. I figure there are only two possibilities either the LCD unit itself OR the header for the LVDS on the logic board. Any ideas of how to check the LVDS header?
Thanks!

bruinbruin said:

Any ideas of how to check the LVDS header?
Thanks!

Click to expand...

You are now at the stage where you need access to first the LCD, then if that does't resolve the problem the logic board, only substitution will determine what has failed. An AASP or ARS will either have access to those parts, or can order and return if not required. I doubt if you will be able to obtain these parts to fit yourself under the same terms. My gut feeling based upon your picture is that the display is defective, but only substitution will prove it. I've never seen a damaged logic board connector on this model so can't advise what the symptoms would be, but guess they could vary. I have on an older 27" 2010 iMac, a PC repairer was attempting the replace the hard drive and after removing the LCD screws let the LCD fall forward ripping the socket off of the logic board, that was obvious.

Ok, so it sounds like replacing the lcd is the next step. I've found some original displays (new) on ebay for about $240 but I'll also call a local shop to see if they can order. It sounds like you're recommending the local AASP because I may be able to return the part if that's not the problem. I'll let you know what happens. Worst case of course I have to have them repair it entirely. Cheers.

Quick question Steve. So my mac is the Late 2013 3.1 GHz 21.5". According to everymac.com this means the model number is A1418 EMC 2722. Online I can really only find other displays that say 2012, 2013 for A1418 but EMC 2544, 2638. Do you think these are compatible displays? It looks like the difference is the i5 vs i7 processor and that's it. The display specs on the 2544/2638 are the same as on my 2722. From the images they look identical.

see
iMac "Core i7" 3.1 21.5-Inch (Late 2013) Specs (Late 2013, BTO/CTO, iMac14,3, A1418, 2742) @ EveryMac.com

Also, I called a local shop in hopes of buying a part but they said they don't sell the parts but they can repair if I let them do everything. So I'm going to gamble and try it myself. I just need to confirm the part number.

Hi Steve,

So I did order the replacement screen. Hopefully that fixes things. I did take a more careful look at the display and I noticed that on the display in the location corresponding to the dead columns there is a thin layer of padding that looks like it's been moved. It's possible that I did this when I first opened the imac (using the tool provided for breaking the tape seal). It's possible that my tool pushed in on this padding and may have affected something underneath. The 'damage' is extremely slight, barely perceptible but it's in the exact location of the dead columns, so maybe. I tried to carefully see if I could open the display and see what's happened but I had no luck. Anyway I include the attached photo just for curiosity.

Ryan

An AASP is not allowed by Apple to sell spare parts, only to use them in repairs they undertake. If they were repairing your iMac and ordered a display for diagnostics they could return it if it wasn't required.

When I order a display it from Apple it has a part numbers starting with 661-, the descriptions are never as the ones you quoted. Rarely do eBay sellers use or have access to these numbers. In reality the displays from different models of the new style iMac's are the same. Different part numbers have different serial number ranges to tie a display to the iMac's serial number range for warranty purposes. Also, if a display was bought from a non Apple source, and you later wanted it replaced by an AASP or ARS, then the EEE code, the last 3 or 4 digits in the serial number wouldn't match or would be non existent, this then excludes the part from being exchanged.

The Apple devices used to remove the VHB strips are white and have replaceable black thin but sharp cutting wheels. They only cut to a safe depth. The only damage I've ever seen caused by a customer was when they made a right mess of it using a scalpel and cut through the camera flex cable at the top.

I have not forgotten about updating this forum. I ordered the display and the first one came completely cracked. The vendor is sending a replacement. Hopefully I'll have it next week and hopefully the new display will fix the problem. Stay tuned...

Hi Steve (and others). The new display arrived and I installed it (including transferring the heat sensor). The new display works fine. So replacing the display fixed the problem. The moral of the story is that the LCD is extremely delicate (moreso than you would think). Be very careful when removing the LCD and removing the display double-sided tape. Do NOT penetrate too far into the iMac case, just go far enough to remove the tape.

Thanks to everyone for their comments. Hopefully this forum will help someone else in need.

Cheers

Thanks for posting back. Even though I was a computer tech for many years I probably will let the Apple techs handle any repairs that I need for my iMac. I would be a total novice taking my iMac apart and it's too easy to make a costly mistake. Anyway, good luck with your "new" machine and have fun.

Computer Resetting Now, Heat sensor?

Steve (or anyone), I have one more question regarding the LCD replacement. So my new LCD works fine but now my computer is just turning off at random times. It will turn off sometimes while I'm using it OR if I leave it in sleep mode for a few hours, then when I come back the computer is off and requires a full restart. Occasionally I actually have to reset the SMC to get it to come back. I've tried resetting both SMC and PRAM.

I DON'T think it's the new SDD because it the computer was stable with the broken display (and external mirrored monitor). It's possible that something shorted out (not sure how/when that would have happened). I'm also wondering if it's related to the small LCD heat? sensor? So the new display did NOT come with the heat sensor. I removed the sensor from my damaged display and attached it to the new display. It seemed to click in fine and I attempted to reuse the same adhesive and tape from the damaged display on the new display. Are there any tricks to getting this sensor positioned or attached correctly? Could this be the source of my resetting problems? Are these sensors particularly delicate? I'm wondering if maybe the computer is simply turning off because it's not getting a reading from this sensor and thinks that maybe it's overheating (or such).

This is the sensor I'm talking about: 923-0280 - Cable, LCD Sensor, iMac (A1418)

Thanks
Ryan

Computer Resetting Now, Heat sensor?

Steve (or anyone), I have one more question regarding the LCD replacement. So my new LCD works fine but now my computer is just turning off at random times. It will turn off sometimes while I'm using it OR if I leave it in sleep mode for a few hours, then when I come back the computer is off and requires a full restart. Occasionally I actually have to reset the SMC to get it to come back. I've tried resetting both SMC and PRAM.

I DON'T think it's the new SDD because it the computer was stable with the broken display (and external mirrored monitor). It's possible that something shorted out (not sure how/when that would have happened). I'm also wondering if it's related to the small LCD heat? sensor? So the new display did NOT come with the heat sensor. I removed the sensor from my damaged display and attached it to the new display. It seemed to click in fine and I attempted to reuse the same adhesive and tape from the damaged display on the new display. Are there any tricks to getting this sensor positioned or attached correctly? Could this be the source of my resetting problems? Are these sensors particularly delicate? I'm wondering if maybe the computer is simply turning off because it's not getting a reading from this sensor and thinks that maybe it's overheating (or such).

This is the sensor I'm talking about: 923-0280 - Cable, LCD Sensor, iMac (A1418)

Thanks
Ryan