MBP 13” Display Glitches - “barcode freeze” - SOLID WORKAROUND FOUND

EXEC SUMMARY:

The trick is to stop the “squeezing” of the case from causing any movement in the RAM bay. You can do this by putting a couple of strategically positioned “standoffs” between the case and the motherboard.

Pictures in line below.

Pict 1: These to plastic pieces are “covers” for Cat-5 wall jacks. I was lucky to have two of them around. There is nothing special about them other than the fact that they are about 3/64” thick and not conductive. Thats a AAA battery in the background to give you an idea of size.

Pict 2: By placing one across the opening to the left of the RAM bay and one across the opening to the right of the RAM bay, the “squeeze” of the aluminum bottom case will not hit the RAM chip or deflect the RAM bay. What is key here is that the plastic pieces are a) very hard and b) resting against FIRM surfaces in the belly of the Mac.

Pict 3: Note the height of these pieces relative to the rest of the components. They don’t stick up much - just enough.

Pict 4: Finally, to make sure they stay in place, throw a little electrical tape over them and put the cover on.

Yes - I know, its undoubtedly an electrical problem caused by some intermittent mechanical failure due to a poor design on Apple’s part. This solution stops the symptom from occurring, it doesn’t do anything else.

If you want the longer story, read on…

BACKGROUND (worth the read I think):

In an earlier post, I described a mechanical solution to the MBP 13” problem of having the display show columns of gridlines from top to bottom, spaced about 2 inches apart the whole way across the screen.

This problem was very reproducible by simple “squeezing” the bottom of the case gently just underneath the lower left portion of the keyboard (the general region from CAPS LOCK key over to the F key and down the SPACE bar). In fact, you don’t have to be too precise with your squeezing to cause the problem.

The problem appears to be harmless outside of the fact that it freezing your machine and requires a reboot.

MY THEORY:

I agree with Xheia https://discussions.apple.com/thread/6481657?answerId=29596089022#29596089022 and others that the bottom RAM chip removal does stop the problem. I experimented by emptying that slot, putting the case on, squeezing multiple times - no crash. Put a RAM in ONLY the bottom slot and it failed instantly on squeezing. Back to RAM in both slots; fails instantly on squeezing.

Then thought that perhaps the original APPLE RAM (2GB chips) would behave differently. So I tried the 3 tests above with those and got the same results.

On the 2011 15” MBP case, Apple welded a couple of aluminum standoffs in strategic places which had the effect of the case not able to be deflected enough to reach the RAM bay. There is no such standoff on my mid-2012 MBP 13”. THIS WAS THE CLUE.

SO, the failure from squeezing the case is caused when the aluminum deflects against the RAM bay. Something about this deflection, which causes the RAM bay to move triggers the failure that seems to be associated with the bottom slot in the RAM bay. I have no idea what that is exactly, but when you keep the RAM bay from moving - or I suppose the RAM from moving in the RAM bay, then you prevent the failure.

SOLUTION:

Is revealed above in the Exec Summary. I’ve squeezed and squeezed and squeezed the case and cannot cause failure. I have TWO 8 GB Crucible memory chips installed. It is working just fine.

NOTE: the downside to having only one RAM chip installed is that the RAM access has poorer performance as the MBP was designed to have RAM in both slots. So an 8GB in one slot will perform worse than 2x 4GB in two slots.

My earlier post is not entirely useful, but if you want to read the tome, its here: https://discussions.apple.com/thread/6481657?answerId=29696916022#29696916022

ASIDE: There was / is a “3 tones” problem where the machine repeatedly sounds 3 death tones instead of trying to start up. That may be associated with this, but for me it went away after sometime shortly after I got the machine to stay up long enough to get Yosemite installed and upgraded to El Capitan. It may go away if you simply reseat your RAM chips.