This Story Posted:
December 2nd
12:53 AM/CST


Tuesday, December 2nd

Top Story
Time Is Not On Your Side: Hardware Problem Hits IR Port?
[12: 53AM] Geoffrey M. Fink and Mike Kruze write us to tell a remarkably strange problem that they have found on PowerMac 6500s and other Macs with built-in IR ports. Their tale is long and detailed and they are seeking information from other users who may have experienced similar problems with these Macs. We are including their message to us in full:


We've seen some bizarre bugs, both in hardware and software, but this one has to be among the strangest ever. We apologize for the length in description, but background is necessary for identification of the problem. Read on.

For nearly a year and a half now, we've been studying a phenomenon known as "Time," a problem that occurred periodically in a lab of 25 Power Mac 6500's at our locale. A user would boot a machine, and after starting up normally--including the execution of any apps in the "Startup Items" folder--experience what would appear to be a completely frozen machine (including mouse functionality). The user would not even be able to use the command+control+power-on sequence to force the machine to restart! And, since the power button on the 6500's is software controlled, the machine couldn't even power off; instead, pulling the plug was the only option of restarting the machine.

Some time after a few users experienced this phenomenon, it was discovered the machines were not actually freezing entirely, but only for extended periods of time (thus, "Time" became the name). When a machine completely finished its startup cycle, the mouse would first rapidly decrease in responsiveness, and then seemingly stop altogether. Interestingly, the machine would only remain in a "frozen" state for a few minutes of time, then carry out a sequence of commands that were given to it while it was frozen, then resume its frozen state. Thus, if a user hit the power button while the machine was frozen, 5-10 minutes later, it would turn off. Same with mouse movement. Or keyboard commands. In addition, when we brought up the debug box (after waiting several minutes for it to appear), initiated by command+power-on, the mouse and keyboard functioned perfectly. When the debug box was closed, the computer froze again.

At first, the problem was thought to be drive corruption; booting off of Norton Utilities and Tech Tool Pro CD's, the machines in question were examined. No serious errors on any of the machines were ever found, not to mention the machines functioned normally when running off the CD's (no freezing). Restarting again off the hard drive following examination yielded no fix; the machines would just freeze again. We also noticed that the computer would still freeze if we disabled extensions during startup.

Some machines were simply left on for a few days, either by accident or otherwise. Eventually, by some oddity, the machines would recover over time, without explanation.

Swapping hard drives between working and dead machines would not even fix the problem--only swapping motherboards. We seriously began to believe 6500's were inherently of poor quality.

But then, a breakthrough occurred a few days ago, after having consulted with another person in the IS department of our lab (who conveniently posted abridged results of our experiments to the Mac Managers list a few days ago): we had experimented with a watch, capable of sending IR remote control commands to common brands of televisions. 6500's--and several other types of Macs--have IR receivers on their front panels, for use with the Apple TV/FM Tuner card (which includes a remote control). The Macs respond to any Sony TV-compatible IR commands; thus, with the watch set to Sony mode, the machines could be remotely controlled to an extent. Volume could be changed or muted, the machines could be powered off (or on!), and the Apple Video Player could even be launched with the TV/Video button. All commands, except for volume changes, are accompanied with a "Click!" from the machine's speaker.

After nearly a year of pondering, we narrowed the freezing problem down to one cause: the power button! Holding down the power button on any Sony TV-compatible remote control for an extended period of time (for instance, holding it down long enough for the machine to turn both off then back on) to a 6500 would essentially disable the machine for weeks at a time.

The cure? Simply shoot the Mac with another Sony command, and presto--the Mac unfreezes and returns to full functionality. Another fix also appears
to work, but only intermittently: three machines independently experimented upon were resurrected by pulling the machine's power plug, and then pressing its power on button. This would theoretically discharge the entire motherboard completely. A fourth machine, however, did not respond to this "cure."

Indeed, this is a serious problem. But is it only with the 6500's? Yes, and no. The experiment was conducted on several other machines: a 6400-series Performa, a 5500-series LC, a 5200-series LC, and a 6200-series Performa. Results were similar, but surprisingly not the same. The 5500 was almost as dramatic as the 6500's: while never entirely freezing, machine response was so poor that the mouse could barely be moved enough to click a button, let alone pull down a menu. The 6400 and 6200 reacted identically: both suffered a slight slow down, enough to make the mouse's animation appear "jerky," almost akin to that of a poor LCD display, or older Windows-based machines. It wasn't smooth like Macs normally are. Otherwise, those machines were OK. The 5200, however, did not seem to suffer any "damage;" upon startup, it continued as before.

All machines tested were instantly cured by sending another IR command.

To throw in yet another variable, versions of system software were also changed, but never cured this mysterious IR-based problem. Some 6500's were running At Ease 5.0, some Mac OS 8.1, some Mac OS 8.0. The 5200 was running At Ease 3.0. The 5500 was running Mac OS 8.1. The Performa 6400 was running System 7.5.5. The Performa 6200 was running Mac OS 8.1. Almost surely the OS version did not affect the problem.

And, keep in mind, this is *NOT* the IrDA port found in, say, some PowerBooks. This is strictly for the IR receiver on the front of a few Macs.

The actual error which occurs is currently unknown. Certainly an explanation is needed. It appears some sort of fairly low-level machine function is "overloaded" or crashing when extended power-off commands are sent, somewhere at the motherboard level, independent of the OS version.

The solution: either 1) ensure you are careful when turning your machine off with a remote control! or, 2) launch the Apple Video Player, go to the preferences dialog box, and make sure that power off's are not allowed via remote control.

In a lab environment like ours, though simply turning off that function via software isn't enough; some users still feel the need to bypass At Ease or in some cases Fool Proof, and re-enable the power off feature. In other cases, such as in the home environment, a user unaware of this problem could accidentally disable his/her machine, and without knowledge of this problem, wind up purchasing a new logic board.

This is a pressing situation that needs to be resolved. If anyone has any further information regarding "Time," has experienced the bug, or knows of an actual fix for it, please contact us immediately. We will happily compile and post any information given to us as needed.

Your patience is greatly appreciated. :-)

Thank you,

Geoffrey M. Fink, Now Click


Mike Kruze

Thanks to Geoff and Mike. They have requested that all mail be sent to [email protected]