Reviving a Non-Responsive 7300/200

I am happy to report that the Happy Macs lab is once more fully operational, after a move of 100’s of miles from its old home to its new home. Of the 28 or so computers that were moved, there was only one “casualty” – my cherished Power Macintosh 7300/200.

PowerMac 7300-200 Image

It would be fair to say that over the last few years, I have lavished many months’ worth of time on it. It has been an essential test bed for almost every new concept, card or technology that I have dug into. It has been heavily upgraded, has a leading edge set of applications installed and has been so reliable that I use it to host an internal Gopher server that the rest of the lab accesses as need be.

Consequently, I was more than just a little distressed when I unpacked it, assembled it and pressed the Power button, only to be greeted by… well, nothing! OK, not quite nothing. The power light came on and the two hard disks spun up, but that was it. There was no startup chime, no video, no response to keyboard start up shortcuts and in general, no signs of intelligent life at all. Even though I packed every computer myself, and moved all of the boxes personally, the process of moving is a physically challenging one for an older machine given the inevitable bumps and bruises along the way. Had my prized 7300/200 suffered fatal damage?

At first, I was concerned, but hopeful. The boxes had been in storage for six months during the move. Perhaps the motherboard battery had expired in that time. I replaced it with a fresh one. No joy. Moving does involve inevitable physical jolts to the boxes. Had a card dislodged from its slot? I checked every card, including the removable CPU card. Everything was snug in its slot. Still no signs of intelligent life. Speaking of intelligence, in the computer world intelligence comes from the CPU. I have an upgraded 500 MHz G3 card slotted into the 7300’s CPU slot. Perhaps it had died in the transfer? I gently extracted it from its slot and replaced it with the original 200 MHz CPU card. The machine remained stubbornly silent. No chimes, no video, no life.

Sonnet 500 MHz G3

At this point I moved from “concerned” to more like “worried”. With physical bumps and bruises comes the possibility that a delicate solder joint somewhere had snapped, in which case it was simply all over (I lack both the skill and the equipment to detect and repair this sort of damage). I also considered the possibility that a cantankerous capacitor had blown somewhere, and spent no small amount of time examining the motherboard and the plug in cards for the telltale signs of cap damage. Again, this was without reward.

OK, clearly “inspiration” was not going solve this issue, so I moved on to “perspiration”. Keeping the case open, I began methodically removing every plug in card (video, IDE and USB) one at a time, and every memory module, until the machine was essentially stripped to its essence.

Power Macintosh 7300 Open

Still it gave no indication that there was any life left in it. Finally, I was left with only the plug in CPU card, which I had already ruled out as the source of the problem in my early “inspiration” testing. Still, the CPU card was all that was left, and if I was going to have admit that this machine was dead, I was going to (re)try this first.

I know that you know what happened next, because the perversity of inanimate objects almost predicts it! I replaced the 500 MHz G3 with the original 200 MHz 604e, powered up for what I thought would be the last time, and was greeted with a robust startup chime! I hardly believed my ears! The machine proceeded to execute the boot process, although it quickly ran into trouble due to a critical shortage of RAM. Ultimately, a minimal version of Mac OS 9.1 managed to project itself onto the display and there was life!

So… I had lost the 500 MHz G3 CPU after all! Well… not so fast. I am nothing if not methodical, and so now I extracted the 200 MHz CPU and replaced it once more with the (by now very suspect) 500 MHz CPU and applied power once more. Once more the machine chimed vigorously and booted into a minimal Mac OS 9.1. This is NOT what I expected, but it was very welcome indeed. I powered down and repeated to be sure that this was a sustainable result. It was.

After that, I slowly, methodically began replacing everything that I had pulled out of the machine. The RAM was first, and with a full complement of RAM came a full boot of Mac OS 9.1. The video card was next, then the IDE card, restoring access to the second hard disk and finally, the USB card. When it was all said and done, I had simply removed everything and replaced it all. I had of course reseated everything in the process, vs. just checking that everything was snugly in its slot, but nothing more.

Reseating the CPU seemed to be the breakthrough point, but I had done that much earlier to no effect. I really have no idea exactly what caused the original failure, nor do I have any real idea how what I did resolved it. However, it IS resolved, and the machine has been starting up reliably ever since.

The moral of this story? Be patient, be methodical and try everything at least twice! The machine is not dead until you give up on it!

 

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