Archive for November, 2004

A quiet iMac DV

November 28th, 2004 — Wordman

A couple of years ago, as fallout from a layoff, I found myself with a pair of 400 MHz iMac DV machines (“grape” and “blueberry”, for those keeping score). One of these sits under my desk, running software that will likely be illegal soon. The other has been deployed in the kitchen (more on that in a later entry).

As this model was discontinued in mid 2000, these machines were starting to show their age. They had a number of problems that I vowed to handle when I got around to it. I happened to get around to it late in 2004, but only after spending a great deal of time tracking some information down. This post intends to distill this information into one place for those looking to do similar things. (I found many such people asking for help, and not getting answers). The problems to solve were these:

  1. Intermittent video problems
  2. Intermittent boot problems
  3. Inability to turn off the internal monitor and use only the external VGA connection.
  4. Limited disk space
  5. Noise

It turns out that the first two problems are related. Earlier iMacs had a number of problems with their firmware and analog video boards conspiring in ways that manifest in random naughtiness. I’d seen several variations of the behavior on these two machines. Sometimes the internal monitor would not work at all. Sometimes it would display only very faintly or all in green. Sometimes a reboot would get past the boot chime and then die. The blueberry machine provided the drive to fix these machines when it started exhibiting the latter behavior all of the time. The grape machine could boot, but seemed locked in “dim display” mode.

After far too long searching for fixes to this problem, I happened across a link to an incredible troubleshooting page for this exact problem. Why this didn’t show up first (or even in the first few pages) in a Google search, I don’t know. Hopefully it does by now. In any case, this explained the problem and provided some great things to try.

According to this page, these problems result from old firmware, and the trick is to get the machine to boot long enough to upgrade it. This presented me with a problem. Supposedly, you cannot run OS X on this model unless the firmware has been upgraded to the latest version, the same version that fixes the problems. Having run OS X on these machines since the 10.0 beta, I assumed I had the correct version, but still had the problem. The machine I could still boot showed the latest 4.1.9 firmware version, but still had the dim display.

Thinking I was probably in for disappointment, I tried the troubleshooting tips with the blueberry machine anyway. I had what the page called “symptom S4”. I found that the older version of the page was a little easier to follow, but neither it nor the current version actually solved my problem. I ran through the firmware page up to and including the “intermediate” section, without improvement (though it turned out I had to replace the battery, so that probably helped some). Not thrilled about exposing myself to high voltage, I tried a few other things before moving into the “advanced” section.

I was under the impression that the extra power draw from the hard-drive spinning up was overwhelming the power supply. To test this, I pulled the power of the hard drive (the white plug with red, black and yellow wires coming out of it) and tried booting from an OS 9.1 CD. This worked fine (though, of course, no hard drive mounted).

I shut the machine down and, just for fun, reconnected the hard-drive power. And what do you know, the thing rebooted just fine. It may be that having booting it in 9.1 or, perhaps, just the change in hardware configuration managed to reset the PMU or something. Not sure. In any case, if you have nimble fingers, you can actually do this through the RAM access slot without taking the machine apart.

Once I got the machine to boot, lo and behold, it’s firmware version shows as 4.1.7. How I got OS X on this box in the first place, I do not know. Such a thing is supposedly “impossible”. Upgrading it to 4.1.9, however, turned out to be easier said than done. This is because the 4.1.9 updater only runs when booted into OS 9 from a writable volume. Since I didn’t run classic on this box (didn’t want to spend the disk space) and booting from a CD wouldn’t work (not a writable volume), I didn’t have a writable OS 9 boot disk. Further, something in the OS 9 install CD just refused to recognize the machine’s disk as one that could handle OS 9. After trying a whole bunch of weird Firewire setups, my problem suddenly resolved itself when the OS 9 installer started working for no evident reason. I have no idea why this happened but, once done, the firmware upgrade worked fine, and did solve the boot problem.

This left the dim display on the grape machine. It had the correct firmware, but still had the problem. Changing the contrast and brightness didn’t help. On a forum, I spotted a solution so obvious I can’t believe it took me so long to try it. All I had to do was go into the Display preference panel, go to the Color section and hit the Calibrate button. This process ended up resetting the display just fine.

So, two problems (including the biggest one) down, three to go. I still have found no solution for turning off the internal monitor while leaving the external port active. I suspect that I might be able just to cut the power to it, but haven’t found the schematics for it. If you know how, let me know. I’m fairly certain that there is no purely software way to do this.

The last two problems also turned out to be related. The iMac DV has no internal fan, so nearly all of the noise it generates comes from its hard drive. If you haven’t had the pleasure, the sound isn’t a typical computer hum, but more of a whine. It’s the type of sound that still thrums in your ears once it stops. So, finding a high(er) capacity, quiet hard drive seemed the obvious solution.

It turns out, this was less than obvious. In the first place, finding what kind of drives the iMac DV could support was a bit of an exercise in futility. Unlike most Macs before it, the iMac used IDE drives, not SCSI. All the information I could find was found in crumbs in forums, mostly unconfirmed rumors:

  • Rumor 1: Drives faster than 5,400RPM overheat the iMac DV. I’m not sure if this is true, but I believe it. The 4,200RPM drive that shipped with it ran the machine hot enough, with no internal fan. So, this set a spindle limit, which turned out to limit the drive selection significantly, as most higher capacity drives are faster than this.
  • Rumor 2: Drives larger than 128GB cannot be read iMac DV. I suspect this is just plain wrong, but saw it mentioned more than once. This seems like it would be more of an OS limitation, so might have been true once. I seriously doubt it is true now. I turned out to be moot in my case, because drives larger than 128GB went over my price target.
  • Rumor 3: The OS must reside on the first 4GB of a disk for the iMac DV. This is almost certainly false, considering that a) even the old, loud drive was a 10GB in a single partition and b) it doesn’t make any sense. I ignored this rumor, so far with no ill effects.

So, I was looking for a 5,400RPM IDE drive of 128MB or less. And it had to be quiet, which led to the next problem: what’s quiet for a drive and how do you find out? After some looking, I found Hardware Central, which not only lists the sound output of hard-drives in decibels, but has excellent search filtering as well. Sifting through the various choices was more annoying than it needed to be, but I settled on the 120 GB Maxtor DiamondMax 16. At the time, Tiger Direct sold these for the lowest price, around $70.

I bought one for each machine. They installed easily (well, as easily as a drive can be installed into an iMac), work great and are nearly inaudible. They do run a bit hotter than the old drives, but so far, so good.