It is our job as a repair shop to find the exact component or components responsible for a computer’s failure. Sometimes, it can seem that a major (and costly) component is responsible for a failure, but we always take the additional steps necessary to conform that a less costly part is not actually to blame.
This is often the case with hard drives, optical drives, and inverters. Before we arrive at a final diagnosis, we test a good interconnect/cable from the suspected module and the main logic board after we see if a simple re-seating fixes the problem. Jon Spaulding, the most senior member of our technical services team, mentioned to me that he’d found several faulty interconnects for unibody MacBook and MacBook Pro in the past few weeks, so he’s now especially careful in diagnosing suspected hard drive failures.
I remember an Xserve that came into the shop a few years ago because its optical drive wasn’t working. The server had been in storage for about a year, and needed a fresh install of Mac OS X server, but the administrator couldn’t perform the installation without a good drive. I’d suggested he put his laptop into “Target Disk Mode“http://support.apple.com/kb/ht1661?locale=en_US and essentially turn it into an external disk drive, but she preferred a fully functioning server complete with optical drive.
We don’t service too many Xserves, so I didn’t have a spare known-good optical drive to swap in for testing, so I went ahead and ordered one up. It didn’t fix the issue, so I marked the drive as dead on arrival, and its replacement arrived the next day. When that didn’t help, I ordered up the interconnect, and the issue was solved. The repair ended up costing about $200 less than I’d originally anticipated.
So, for those of you out there who do self diagnosis on problematic computers, keep cables in mind. Odd as it seems that a simple cable can fail, rest assured that they do!