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There are two ways to diagnose computer problems on Macs. One way is by using Apple’s own diagnostic tools like the Apple Hardware Test AHT or the Apple Service Diagnostic ASD. These tools are good for basic diagnostic tests and for verifying the repair. The tools that I recommend are more for a system stress test, and from my experience, AHT and ASD do not stress the system enough.
For everything that can be run from Mac OS, I recommend you to install a separate Mac OS on the flash drive. This is convenient because it is not necessary to take out the hard drive. On some models, the hard drive is buried deep inside the laptop.
The flash drive or external hard disk is a great tool that can make the diagnostics easy. On our installation we can install all the usual programs, for example, programs to test the hard drive and look for bad sectors like the Drive Genius or CPU Test. We can also retrieve all the data from not booting the Mac and so on.
A very significant number of faults happen because of laptop graphics defects. This is true for ATI and nVidia graphics. There is no tool that can test and show that the BGA soldering is faulty. For PC’s, there are a few tools that can show a developing fault. But, they are not always accurate and if the system does not boot up at all, we can assume that it is a faulty BGA on a Graphics card or south bridge. AHT and ASD can reveal a part of such a fault, but not one hundred percent. This is especially true when the graphics part has a fault that is not permanent.
Once, we had a MacBook Pro still under warranty, which was overheating and crashing randomly with a kernel panic.
Figure 1: Kernel panic on a MacBook Pro
I ran ASD and it revealed a graphics fault as shown below.
Figure 2: ASD showing graphics fault.
At the Apple genius bar, they told me that this was normal and I shouldn’t leave the laptop on the bed and let it overheat. I had no other option but to install Windows on it and run a system stress test. Other laptops pass the test, so why doesn’t MacBook?
Figure 3: My favorite OCCT running on Mac.
After about 20 minutes, it restarted and then crashed again with kernel panic. I need to mention here that it showed many different symptoms including:
• stopping on a kernel load
• stopping on the booter
• nine beeps (three short, three long and three short) after powering on
• crashing on chime
• one beep after it powered on
• three beeps after it powered on
After the Macbook was returned to the Apple store, they replaced the motherboard.
I will now jump to the hard disk diagnostics. On a Mac, Disk Genius can be used. If we need to know more about the hard disk’s health, we need to take it out and connect it to a Windows PC or use the Windows installation on the Mac. I use GSmartControl for this purpose and it retrieves S.M.A.R.T. data.
Figure 4: Hard drive diagnostics with GSmartControl.
GSmartControl allows me to retrieve data from the hard drive that is inside the computer and from an external connection. It also allows me to make the decision about the hard drive health much faster than with HDTune or using the laptop EFI warnings.
The only two tools that do not run on Mac’s are MemTest and UBCD4WIN. MemTest is very handy as a memory test and we can check the Mac memory on other computers, or we can use ASD and AHT.
Computer Repair Lessons Continued: 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
Me holding a laptop hard drive
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