Power Mac 7100s Deaths

[Mike Richardson]

7100/66 - Battery blew up. Took out the motherboard, ruined case metal. Demanufactured 12/9/2008.

7100/80 - Just won't boot. Tried new: PRAM, ROM, Video Card, PSU.

Near death:

7100/66av - Boots, poor chime, sound, bad caps. Old failing HD.

7100/66 - No chime, boots, no sound, bombs during boot.

The 66av may be repairable with a cap job, maybe the other one as well. The battery one was a total loss for the case, mobo.

 

[Dennis Nedry]

7100/66 - Battery blew up. Took out the motherboard, ruined case metal. Demanufactured 12/9/2008.

I had a battery that blew inside a 6100. The metal case and power supply got all rusted and there was acid and considerable brown crap all over the logic board. But I washed it all off with concentrated isopropyl alcohol and it works just fine. It really got into the built-in motherboard RAM, but I scrubbed all the rust off with q-tips and a toothbrush and the Mac, by every indication, is working fine. The metal is still all rusty but you can't see that from the outside.

 

[trag]

Mike you probably already know this, but many 7100s die or won't work because the heat sink grease on the PPC601 turns to powder and stops doing its job. Then, either the CPU overheats and causes random freezes/corruption, etc. Or (worse) the CPU package cracks. I have a pile of 7100s and 6100 with cracked CPU chips.

 

[Dennis Nedry]

Would it be advisable for me to remove the heatsinks from all of my 6100s and 7100s and apply new grease? I have a lot of them and they all work right now.

 

[Charlieman]

Great post, Trag. I hope you have more time to revisit us, ideally with nifty Mac enhancements ;-)

If there is a failure pattern for the 6100 and 7100, it may apply to the 8100, 7200, 8200 etc, clones and PDS accelerators that use the same package. However, I don't consider lifting the heat sink as a trivial maintenance procedure.

 

[Unknown_K]

I have a daystar PDS 601/66 that quit working, the chip looks like it might be cracked (lines showing under the blue lablel) and the heatsink on the chip is purple. Going to check my others 601 machines before I fire them up again along with my 601/100 PDS card.

 

[trag]

Would it be advisable for me to remove the heatsinks from all of my 6100s and 7100s and apply new grease? I have a lot of them and they all work right now.

If you do so, you must first clean off the old grease. Rubbing alcohol works fine for this. Use the 91% stuff if your local store carries it.

There are two primary cautions to observe. First, do not apply unnecessary downward force to the CPU. It is crackable. Second, do not overapply the new grease. The stuff can be conductive. If it runs off the chip onto the pins around the edge of the chip it can cause shorts and kill your 601. The grease is just filling the imperfections from flatness in the 601 die and the heat sink. It doesn't take much volume to do that.

 

[trag]

Great post, Trag. I hope you have more time to revisit us, ideally with nifty Mac enhancements ;-)

Thank you for the kind words. I have no new enhancements in the chute right now. If I ever find the surface of my bench again, I'll finish up my IIfx RAM--I still have boards and chips sitting there, and I have a bunch of 6880 ATA cards to convert to 6880Ms--although for those latter I think I may have procrastinated so long that the market has evaporated out from under me. Still, I got them pretty cheap.

If there is a failure pattern for the 6100 and 7100, it may apply to the 8100, 7200, 8200 etc, clones and PDS accelerators that use the same package. However, I don't consider lifting the heat sink as a trivial maintenance procedure.

It could apply to any of them, but the 7100 is where i've most commonly seen it. In theory, on a board with a cracked CPU it should be possible to steal a PPC601 from a PM7500/100 daughter card. The biggest problem there is that the PPC601/100 is a 3.3V part and the PPC601/60 - 80 is a 5V part. The supply voltage is easy enough to change (Apple used an adjustable voltage regulator) but I'm not sure the I/O levels are compatible.

 

[Mike Richardson]

Mike you probably already know this, but many 7100s die or won't work because the heat sink grease on the PPC601 turns to powder and stops doing its job. Then, either the CPU overheats and causes random freezes/corruption, etc. Or (worse) the CPU package cracks. I have a pile of 7100s and 6100 with cracked CPU chips.

That's something I will also need to check. A lot of 5260s I had were bombing early in the boot process, and re-pasting the CPU fixed it right up.

It also seems the caps are going on the 7100s.

 

[Hrududu]

My 7100 died a few years back, but it was just the power supply. Its one of only 2 legacy Mac's I've ever had die on me.

 

[madcrow]

Mine didn't really die, it sort of petered out over time. It never worked 100% to begin with (it wouldn't boot any OS newer than 7.6, despite the fact that it should have been fine with everything through at least 8.6) and over time it got finickier and finickier about booting. Eventually it just wouldn't turn on at all, so I took out the SCSI HDD (and maybe the floppy drive, as auto-eject Mac floppy drives can be a PITA to find) and recycled the rest.

 

[Bolle]

I had a 9150 board in my 950 that died when the voltage regulators for the cpu asploded.

 

[trag]

I had a 9150 board in my 950 that died when the voltage regulators for the cpu asploded.

It's fairly easy to steal a replacement from a 7500/100 CPU card. Since there is no CPU card slower than the 601/100 card those cards are usually cheap to free if you can still find any of them laying around.

However, if the regulator took anything else with it when it went, then the fix is not so simple.

I can't remember the exact part number but it's a linear technology part.

 

[Bolle]

it did melt parts around it before it exploded and it took the solder pads with it when releasing its magic }