Many stories of glass+LCD falling off after resealing (to upgrade to SSD, add RAM, stand hinge repair) I guess mostly the heavier 27" glass+LCD.
Having done 3x 21.5 and 1x 27". I can see several problems.
ifixit direction suggest to tilt the screen after sticking on the double sided tape on the bottom edge (to connect LCD + backlight + clean glass in front of camera) This is a poor procedure due to several reasons
A much better way is
Was able to get almost completely flush on top and 2 side edges doing this method
Some people say easier to tape bottom edge on the glass first. This might be challenging if iMac has a microphone port on the bottom edge. Tape has a cut out that needs to align over the hole (pic doesn't show iMac with mic hole but shows tape cut out)
Peeling off the dark blue tape around the mic hole cutout was very much harder to peel off. Will need to inspect that area more carefully next time to see how to better peel off. Imaging trying to do this difficult peel tiling the glass and pivoting on the bottom edge.
Poor Taping Surface
Tilting up to release the bottom edge tape (per ifixit and many people's effort) will likely leave much glue residue on the bottom edge to clean (not the mention the chance to crack the glass especially on the 27" with so much larger glass) Only tilting up to loosen the bottom gap slightly follow by cutting it ( link )
Peel off the cut tape slowly and watch if shiny glue residue gets left behind. Try change peeling angles to reduce amount of residue left behind for leaning.
Prime tape sticking surfaces. Got this from AliExpress. Maybe not the real thing but surface primer desirable.
Careful and not tape shut the breathing ports along the 2 edges. ifixit suggest to hold tape down on 1 end with spudger. Refrain from pulling and stretching the tape tight and straight to lay it down flat. It will stretch the tape which adds to the stress on the sticky surfaces. Potentially seal the breathing ports. Better go slowly and few inches at a time. Again, 2nd pair of hands quite helpful.
Roller and some hot air along the taped edges is probably helpful. Not too much pressure on the roller to crack the glass. Not too hot air to warp the LCD diffuser sheets.
Addition Security
Can use 30lb fishing line and make a safety. Loop around the fan stud and stick against the metal LCD frame (use surface primer also) Note it needs to be stuck high enough to clean the fan or glass+LCD will not close. Pic shows doubled the fishing line and probably just a little too short.
Having done 3x 21.5 and 1x 27". I can see several problems.
- Glass+LED weight not resting on bottom frame edge per ifixit directions
- Poor quality double sided tape. I buy premium quality from mobilesentrix (pro repair shop parts distributor, need business license to buy)
- Poor surface preparation
ifixit direction suggest to tilt the screen after sticking on the double sided tape on the bottom edge (to connect LCD + backlight + clean glass in front of camera) This is a poor procedure due to several reasons
- Peeling the tape can be very difficult. I've had cases where I needed to tilt the screen nearly 90 degress to peel the tape. Some tape also very difficult to peel around the microphone cutout area.
- After peeling and tiling back. It is quite common for the bottom of the glass+LCD to float above the resting edge. This means the entire weight of the glass+LCD assembly is secured by the double sided tape rather than also resting on the chassis and therefore less stress on the tape.
A much better way is
- Fully connect the iMac LCD+backight + testing first.
- Pivot on the top edge and peel the bottom edge tape first. Followed by peeling other edges with < 1/2" gap lifting up on the top edge to peel the remaining sticky tape protective cover.
Was able to get almost completely flush on top and 2 side edges doing this method
- Still had < 0.5mm gap on the left lower corner. I guess with double sided tape, one side is going to catch first and very difficult to get perfect. Another pair of hands would be very helpful to lower the bottom edge super slow and double checking alignment. Ideally hold screen only 2-3mm above the tape and check both corners for alignment. Magnifying eye wear very helpful.
- Next time I might consider paint mixing stick to help lower the bottom edge more gradually and precisely.
- This pic is for a 21.5" 27" is much heavier and challenging. 27" is large enough that the center of bottom edge might be lower than the corners just from weight.
- Suction cup could lose suction quickly. Again, 2nd pair hands quite helpful.
Some people say easier to tape bottom edge on the glass first. This might be challenging if iMac has a microphone port on the bottom edge. Tape has a cut out that needs to align over the hole (pic doesn't show iMac with mic hole but shows tape cut out)
Peeling off the dark blue tape around the mic hole cutout was very much harder to peel off. Will need to inspect that area more carefully next time to see how to better peel off. Imaging trying to do this difficult peel tiling the glass and pivoting on the bottom edge.
Poor Taping Surface
Tilting up to release the bottom edge tape (per ifixit and many people's effort) will likely leave much glue residue on the bottom edge to clean (not the mention the chance to crack the glass especially on the 27" with so much larger glass) Only tilting up to loosen the bottom gap slightly follow by cutting it ( link )
Peel off the cut tape slowly and watch if shiny glue residue gets left behind. Try change peeling angles to reduce amount of residue left behind for leaning.
Prime tape sticking surfaces. Got this from AliExpress. Maybe not the real thing but surface primer desirable.
Careful and not tape shut the breathing ports along the 2 edges. ifixit suggest to hold tape down on 1 end with spudger. Refrain from pulling and stretching the tape tight and straight to lay it down flat. It will stretch the tape which adds to the stress on the sticky surfaces. Potentially seal the breathing ports. Better go slowly and few inches at a time. Again, 2nd pair of hands quite helpful.
Roller and some hot air along the taped edges is probably helpful. Not too much pressure on the roller to crack the glass. Not too hot air to warp the LCD diffuser sheets.
Addition Security
Can use 30lb fishing line and make a safety. Loop around the fan stud and stick against the metal LCD frame (use surface primer also) Note it needs to be stuck high enough to clean the fan or glass+LCD will not close. Pic shows doubled the fishing line and probably just a little too short.
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