Friday, 29 July 2011

No preboot keyboard shortcuts working on White iMac 17" and 21"

We've had both 17" and 21" white iMacs for about 5 years and in that time I've re-imaged them at least 5 times (once a year) using NetBoot (hold down "N" on preboot). But recently I've noticed that these iMacs no longer register any pre-boot shortcuts including reset PRAM ("alt" + "cmd" + "p" + "r"). This means if I have a problem with them (i.e. if the hard disk fails) I won't be able to work any magic on them. Luckily I've not had any trouble yet but in time it'll need sorting out.

I originally assumed it was the last image i'd put on them, or the way in which I'd done it but noticed, but I didn't think that would effect anything pre-boot, like firmware.

I've done a few searches and found mostly mentions of Bluetooth/Wireless keyboards having this issue and one mention of 3rd party keyboards, but no real success finding anyone with this particular problem. I did a few more searches and found this which does sound more promising. The only difference being it does holding down "c" and "alt", but I didn't try these as I just assumed they would work after trying PRAM reset and "cmd" + "s" single user mode. (Never assume anything!)

A person down the bottom says the PRAM battery might have failed, which would make sense as they are over 5 years old and are unplugged for large periods of time (for security measures). The next question: How to replace battery in old white iMacs?

For the time being I shall just have to rely on them working and use the system prefs to alter startup disk.

1 comment:

  1. this is the only place i have seen this prob mentioned. NONE of the pre boot key commands work on my macbook. i can not figure it out. i was just using the preboot keys to fix it a few days ago , now all the sudden none work.

    if you find a fix please post it. thanks bob