Questions about Power Mac 6100 Maintenance and Preservation

[DistantStar001]

Alright. So recently I got a few (new to me) vintage Macs. A Performa 6205CD (see my previous post to see how well that's going), a Beige G3 Desktop, and a PowerMac 6100 DOS compatible. All were, more or less, in decent cosmetic shape, but in testing, only the 6100 gave any real signs of life. Basically, it Bonged! Right away too. So, for now, there doesn't seem to be any issues with it.

I'm not too worried about the G3, as I only bought it for its case (I had another, the guts of which now live in the case of the new one). As for the 6205… well… that's being covered in another post (and I'm trying not to think about it right now).

The 6100, on the other hand, is from what I can tell, a far more… desirable? important? I don't know what the right word is. For me, the point is that it appears to be working and completely intact. And I'd like to keep it that way! (Although, I won't know the full extent of its functionality until the video adaptor arrives. To say nothing of the unobtanium that is the DOS Y-adaptor). Still, before I do anything rash, like recapping the PSU or motherboard, I want to get some advice on the best maintenance for these. I know this is a mid-90s era Mac so leaking Capacitors aren't out of the question, but this may very between models. So how reliable is the 6100's motherboard? What about the PSU? How about the plastics? From what I understand, the fact that both the case tabs are intact constitutes something of a minor miracle. So how can I keep them that way? Should I be taking a 'if it ain't broke' approach? Or should I be more proactive?

Side note: YES! I did remove the P-RAM battery. It was the first thing I did. The thing was dead, but thankfully, it hadn't leaked or exploded.

 

[Juror22]

So how reliable is the 6100's motherboard? What about the PSU? How about the plastics?

The motherboard, like all of its ilk needs to be recapped. The "if it ain't broke" advice doesn't apply since you can't tell until it is too late that caps are bad and have damaged something. I've recapped both of my boards (and my video card) and they are solid.
I have a couple of the PSU's and they seem to be fine (I haven't re-capped mine, but they seem to be better than the LC ones) and I monitor their activity periodically.
I have an opinion about the plastics, but there are others with an opposite opinion, so take it, or leave it.
1) I retr0brite mine, apply UV protectant and maintain them in a air-conditioned environment. No basements, attics or storage units.
2) I take them apart and put them together as little as possible - those clips are poorly designed for longevity and the interior support pieces are worse.
3) I keep spare parts (when possible). It's better to have them and not need them than the other way around.

Everything that is unobtanium comes out of hiding sooner or later, you just need to be patient and wait for your moment.

 

[killvore]

First off - congratulations! These are great machines that are a lot of fun to work with.

In order to preserve the tabs at the back, I would recommend dremeling off the little plastic hook that locks it on to the lower case. Yes it's destructive but it means you will not snap the tabs. If you insist on keeping them, hit it with a hair dryer for a bit before opening to soften the plastics. Here's a shot of inside the top lid so you can see the part I removed.



The 601 should be repasted under the heat sink. Be careful when removing the heat sink, don't put pressure on the middle! I recommend taking the logic board out, pressing down near the corner on the band that secures it, and then using your other hand to release the latch from the opposite side (see photo for where I suggest pressing). You can then unlatch the heat sink on all sides and remove it safely!

Also, it gets pretty hot so you can fit a 40mm fan directly inside the heatsink, it fits perfectly! I've added a picture of one of mine where I also added a copper heat sink to a chip that gets really hot (mine is overclocked to 80MHz)

These machines do need a PRAM battery to boot properly, so you will either need one or a CR2032 adapter to get it fired up.

 

[KennyPowers]

While it is expensive, I guess it's less expensive than the original octopus cable: https://www.ebay.com/itm/225696044975

I'm not affiliated in any way with that seller or product...just making you aware of it

Also, you *can* boot a 6100 without a PRAM battery installed. Push the power button, wait for the machine to chime, then rapidly toggle the power button off and then back on again. It should chime a second time and then boot.

 

[ArbysTPossum]

Heatsinks and fans. If the chip gets hot enough to steal your fingerprint, put a heatsink on it. If the case has stagnant airflow, put a fan in it. A lot of old computers have terrible heat management.

 

[bobcat]

- As mentioned, repaste the CPU
- I had one with a dead power supply, but was able to get it working again with a recap
- You definitively should recap the motherboard
- Be careful with the plastic! Note: you can 3D print new drive sleds and feet if needed
- Replace the hard drive with a BlueSCSI

 

[DistantStar001]

Alright! So I finally got an HDI-45 adapter (as well as a working but VERRY TEMPORARY battery) and was able to give it a proper power test. I disconnected the hard drive, and connected it to one of my LCD displays (I also removed the DOS card as I'm unable to test it right now, and just wanted to see if this thing boots). Once I got the settings right, it game up with the expected floppy/question mark icon. Satisfied that the board was at least working, I reconnected the SCSI cable and tried it with the drive. The drive is actually good (another not so minor miracle, considering it's a mid-90s Quantum). In any case, the computer booted to system 7.5.3 and appears to have been only lightly used.

The whole test lasted less than two minutes, and YES! I can see why so many of you suggested redoing the thermal paste and adding a fan to the CPU. My only question is where can I hook it up for power?

As for the capacitors… I must admit, I'm a little nervous after my last recap on my 6205 (apparently) went wrong. But I will be doing it anyway, as I'm guessing recapping a working board will be both easier and safer than waiting to do it once the caps have leaked all over.

I'm definitely going to have to do something about those plastic tabs. They're slightly bent up. It looks as if the case was never closed properly, and over time, the plastics simply settled into a raised position. Not the worst cosmetic flaw, but I think sanding down the latches will help not only in eventually repositioning them, but also relieve the mechanical strain when the case is closed. I'll probably use sand paper as my dremel skills are not what they used to be.

Also, NO I will NOT be storing this with the battery inside. Having gotten a better look inside, I'm not sure there's enough room for a proper coin cell holder, but an adaptor for the current holder should work fine.

Thanks all so much for the advice!