The Apple Files

Thanks to some pictures of the MacBook heatsink on Flickr, the cause of random shutdowns in the 13″ MacBooks is now clearer! As previously thought, it is indeed an insulation issue. Here’s a close up of a melted heat sensor cable:

The area where the cable insulation melts actually houses a pair of cables and it is suspected that this is where the short circuit triggering a shut down occurs (when those two cables make electrical contact).

Also of interest is the changes that seem to have been made in the heat sink design as part of the fix. The newer heatsink, bearing part number 607-0142 features a piece of kapton tape in between the sensor cable pair. Kapton Tape is a polyimide film that is resistant to temperatures as high as 400°C (about 750°F).

The old and new heat sinks

The fix also includes a piece of sponge that prevents the cable pair’s snap-in connectors from becoming disconnected from the main board.

The Sponge

The Sponge in Place

I must say those pictures have given me a big confidence boost in my MacBook’s repair. Even more so when looking at my repair sheet and seeing the same part number (607-0142) for the heat sink as in the above photo.

Apple should really have explained this problem and fix to all owners of MacBooks with Random Shut Downs instead of stating the obvious by saying “If your MacBook is shutting down intermittently, please contact AppleCare for service.”

The pictures in this post were taken from thatsiebguy’s and youd0ntkn0wwhoiam’s Flickr photos. For larger copies of the photos accompanied by notes please visit the two users’ Flickr pages.

Update: thatsiebguy points out that the problem may not a short circuit but rather heat related alterations in the thermistor (heat sensor) signal. See the full post for more details.