A Crazy Question - do I need a fan? (CC)

[TweedyF]

I was watching an old episode of the Computer Chronicles today in which Charlie Oppenheimer (Mac product manager) points to the fan inside the SE and says, "this is required for any machine with an internal hard drive." Well, like many of us, I've replaced the internal hard drive in (in this case) my Color Classic with a SCSI2SD, so there's no hard drive that needs cooling. And that fan is so damn loud. Which got me wondering, do I need it?

 

Obviously I know the smart thing to do is to leave it in, or at most replace it with a quieter fan. But I wonder if anyone's done any actual research on temperature tolerance of post-Plus compact Macs? How would they do with the fan disconnected?

[360alaska]

In that case he is most likely talking about black and white compact macs. In a color crt mac the voltages involved are much higher, the answer is yes. But with that being said you can probably replace the fan with one that is both of higher cfm and quieter.

[ymk]

I have been running a fanless, clear case SE with a MacSD 24/7 without problems.  The PSU PCB is not enclosed for visual and cooling reasons.  It pulls 28 Watts from the wall and the hottest point I can measure with IR is 51C around the flyback transformer.

 

However, I'm not sure if the @maceffects case passes IR.

 

My Classic, which also has no hard drive pulls 30W, but has a slow 80mm fan to keep it cool.

[360alaska]

Comparing a Mac SE to a Color Classic is not a good idea for a variety of reasons.

[techknight]

not to mention you need to cool that flyback transformer. They arnt getting any younger, and also replacements are not getting any easier to find. 

[joshc]

8 hours ago, techknight said:

not to mention you need to cool that flyback transformer. They arnt getting any younger, and also replacements are not getting any easier to find. 

 

100%. This is the reason to have a fan in any Mac with a built-in CRT.

[techknight]

2 minutes ago, joshc said:

 

100%. This is the reason to have a fan in any Mac with a built-in CRT.

 

Exactly. and itll get to a point where replacement parts are just not available. So once the CRT gets weak and dies, or flyback fails, you part it out and move onto the next one. 

 

Its currently happening with the vintage/antique TV collecting world. CRTs are nearly unobtanium and so are flybacks. all CRT rebuilders have shut down as well. 

 

A good Color 21FJP22 CRT goes for $300 on up alone.... the 7JP4 electrostatic tube is nearly impossible to find now. 

Edited November 3, 2020 by techknight

[joshc]

Yep. I tend to run my compact Macs at ~50% brightness to maintain the CRT components a little longer, it probably doesn't help massively but anything we can do at this point is good as these parts are not easy to replace now, less so in 10 years, and so on...

[Chopsticks]

yeah 100% need the internal fan in the color classic, that analogue/psu board has a lot of high current devices on it that generate lots of heat. as will all electronics that live stressful lives (such are CRT driving circuitry and switch PSU's from way back) the cooler you can keep the ambient temps around those components the longer they will live. for example while you can get caps that are rated at 85C and 105C even if the temps around say are only 50-60C the 105C caps will long outlast the 85C ones. those max ratings are just that, max ratings and overtime the more stress they incur the shorter their life span. do note that goes for other components too, was just using caps as an example 

[Crutch]

I took some highly unscientific measurements of my SE/30 (with accelerator) a while back, measured with a thermistor attached to the little cage directly over the flyback, with the case back off for easier measurement but resting an old copy of Macworld across the top of the CRT to simulate airflow restriction somewhat.  With a fairly standard fan (I forgot which, but maybe a Noctua) vs. no fan, after 20 minutes the temperature difference was about 130°F vs. 100°F.  I’m sure it gets much hotter with the case on and with longer use.  I love quietness but would never run an old Mac beyond the Plus level for long without a fan.

[TweedyF]

Thanks everyone!! I don’t think I would have done it, but I’m very glad I asked 

[Elfen]

I've seen/owned skinny/fat Macs with DIY fan kits in them to keep their analog boards cool. So I would recommend one.

 

The Logic board draws little power compared to the analog board. 90% of all B/W 68K Mac problems start there.

[maceffects]

I strongly discourage the use of fanless AIO 68k Macs.  I even using a SystemSaver on my 128k. Speaking as someone who tried to manufacture new flyback transformers for the 128k-SE/30 the cost is insane.  Therefore, we shouldn’t be expecting replacements.  As a result, we need to keep our current flyback transformers cool. That’s really the main reason for cooling these things. My fans ran twice the CFM as the original fans, so they never get hot. But the originals do a good job overall, unless you have accelerators. You just need to have air flow to keep the flyback as close to room temperature as possible. 

Edited November 5, 2020 by maceffects