running without a fan- Mac SE FDHD

[wgoodf]

my fan is noisy!

i am sure that it is no noisier than anyone else's fan, but recently its been bugging me.

has anyone ever ran their SE without the fan?

i assume it would be more flaky than usual.

really i want the machine used more than it is, i want it standing as a telnet terminal, but the fan annoys so!

 

[joshc]

Just replace the fan with a quieter one, then. Running an SE without a fan is not advised.

 

[wgoodf]

hello wacky - its been a while.

anyway from that you mean just pull it out and stick another one in?

seems simple enough - any provisions or traps i need be aware off?

 

[tomlee59]

Running without a fan is possible, but as you will then have the rough equivalent of a Plus, it's not a great idea.

I believe JDW did some research on suitable fan replacements. Try searching through the MLA archives to see if his posts have that information. Or perhaps he might be prevailed upon to repost this information (assuming that my memory is correct).

 

[Mac128]

Running without a fan is possible, but as you will then have the rough equivalent of a Plus, it's not a great idea.

Meaning, the SE has significantly more robust power supply than the Plus and can therefore endure more heat. However, the Plus does NOT have a hard drive. The full height drives used in the SE FDHD would significantly increase the heat in the case, well over that inside a Plus, as well as block a lot of the front vents in the SE which might otherwise provide reasonable ventilation.

If you were to remove the hard drive and run the SE for a limited amount of time between cool-downs, in an adequately air-conditioned room away from other heat sources, like lamps and external hard drives, and ensure good air-flow around unobstructed vents, it might be safe to run the SE this way. However, it would most certainly increase the strain on the components and thus shorten their life.

 

[LCGuy]

I'd be looking at installing a quieter fan. The Elina Fan was used in a lot of Macs from that era (I have both an LCII and an LCIII with them, they're pretty easy to find), and is very quiet. I think a few people on here have also used Silenx fans, and have commented on them being much more quiet than any of the OEM fans used in the old Macs.

 

[joshc]

hello wacky - its been a while.
anyway from that you mean just pull it out and stick another one in?

seems simple enough - any provisions or traps i need be aware off?

I bought a Silenx 60mm fan to replace the old Elina fan. You have to cut off the 3rd wire and then solder the other two, either to the existing black/yellow wires, or directly into the analog board - either way is fine. I haven't actually done the hack yet, the fan has been mounted in the bracket for a month or two but I still haven't soldered it. I know it will work because fellow member JDW did the same thing and it worked fine with his SE/30. As others have stated, the extra heat from the enclosed PSU and hard drive mean that a fan is really necessary in an SE.

 

[wgoodf]

thanks for the info guys - silenx it is then.

saying all of that - i wonder how a duel floppy SE would fair without a fan - they had them too after all.

anyway -thanks again

 

[joshc]

Well part of the problem is the enclosed PSU. Before the SE, the PSU was exposed on the analog board. But with the SE, Apple used a Sony PSU unit which has its own case and PCB, separate from the analog board. So the extra airflow is really needed, IMO, to help cool the enclosed PSU. Good luck with the Silenx fan.

 

[Mac128]

Well part of the problem is the enclosed PSU. So the extra airflow is really needed, IMO, to help cool the enclosed PSU.

This is an interesting quandary.

First I would say to wgoodf that the second floppy disk would contribute to similar airflow problems as the hard disk, though without generating the additional heat. If I were to even consider running an SE without a fan, I would most likely remove everything I could from the interior, including both floppy drives and run the SE with an external floppy and/or disk drive, which sort of defeats the purpose.

Second, the Apple III was often claimed to have failed due to heat related issues caused by the PSU enclosed Aluminum chassis. However, Manock proved there was adequate heat dissipation and the primary culprit turned out to be a major logic board "fineline" technology design problem. Interestingly enough, a similar solution was implemented in the Macintosh: a heat-sink was installed along the top of the original analogue boards to achieve the same effect, but was quickly removed as it had the opposite effect of blocking the ventilation on top of the Mac. Theoretically, the metal cased PSU in the SE might actually work more akin to the Apple III's chassis, conveying the PSU's heat to its case to better cool it. The case is well perforated on all sides (though the SE chassis actually obscures the bottom perfs somewhat), and the side panel could be removed to further enhance air flow, assuming it does not better dissipate heat in place. Interestingly enough, the SE's PSU is very similar to that used in the HD20, except that the HD20's is fully enclosed and sits beneath the circuit board and the air intake vents. So, when the fan is in operation, it pulls air across the top of the circuit board only, but does nothing to pull air up from around the base of the PSU, suggesting the case itself is acting as a heat heat sink.

While this is all interesting speculation and conjecture, the SE was designed to operate with a fan, and given the quieter alternatives available (even at the time), it's best to preserve the operational life of this 20+ year old Mac by using it as intended.

 

[joshc]

The components in the SE's PSU are placed very close together, most of the capacitors touching. I would think this makes it more difficult for air to travel through the unit. Another possible problem is the close proximity of the PSU to the CRT, which could potentially block some of the airflow. This is in comparison to the exposed power supply in earlier models where these problems didn't really exist. So without a fan I would be concerned about damaging components in the PSU due to excessive trapped heat.

It might also be important to note that most floppy drives do heat up during operation (although probably more so 5.25" than 3.5" drives). Apple included a fan with the SE to try and avoid any reoccurrence of the heat problems users experienced with previous compact models, and also because of the addition of a built-in hard drive.

 

[Mac128]

So without a fan I would be concerned about damaging components in the PSU due to excessive trapped heat....Apple included a fan with the SE to try and avoid any reoccurrence of the heat problems users experienced with previous compact models, and also because of the addition of a built-in hard drive.

Agreed. No one here is recommending you run an SE without a fan. This is all idle speculation. One of these days I will run some thermal tests to satisfy my curiosity.

In addition to adding the fan, Apple removed ALL of the upper vents otherwise present in the earlier Compacts, including the handle vent which alone was later restored to the Classic. This means in the SE, without a fan the hot air only has one place to go: out of the back middle, or the front. Without a vent in the top of the case, there is definitely going to be some warm trapped air which will have to be relieved by conduction which is not likely to fast enough to prevent severe overheating at the top of the case.

 

[Mac128]

It might also be important to note that most floppy drives do heat up during operation (although probably more so 5.25" than 3.5" drives).

I would say definitely less than a 5.25" drive. One more point to make:

After the SE came out, many users found that their FDD would accumulate dust and gunk causing drive problems. This was due to the fact that the fan draws air directly through the floppy slots. So much so, that Apple eventually offered an optional plastic dust shield for environments where this was a problem (ut's a problem in all environments but do you think Apple was going to admit that?). The shield completely surrounded the top and sides of drive virtually eliminating air-draw through it. It would therefore also cause some heat build-up, but clearly not enough to be of concern (so it is unlikely to significantly increase the heat inside the case either). The Classic eliminated the problem by creating an air scoop which funneled the air directly up from the bottom of the case, and added the vent to the top handle, thereby reducing the draw through the floppy. Later drives of course eventually added a flap to limit the air intake.

Something to keep in mind when you install your new fan.

 

[joshc]

Great point there Mac128 - the plastic dust cover on the later SuperDrives completely slipped my mind.

 

[superpantoufle]

Some more thoughts about the airflow in a SE's case: I built my Macminitosh putting a Mac Mini inside a SE case. And heat is actually the main issue with that setup, with the SE case being nearly hermetic, and the Mini's fan having to do all the job. One way or the other, I would definitely NOT recommend using a SE without a fan more than for a few minutes for testing.

 

[Mac128]

heat is actually the main issue with that setup, with the SE case being nearly hermetic, and the Mini's fan having to do all the job.

I took another look at your setup. It appears that the Mini blocks the entire front vents on the SE as well as most of the inflow from the bottom vents. In theory the bottom vents are the most important vents allowing cooler air from the bottom to flow across the warm logicboard and up toward the heated air inside the case and out the top, particularly where pure convection is concerned. The SE is no more hermetic than the Plus was, except of course for the upper half where heat is surely trapped by the lack of vents. The front/back ventilation (without drives in place) would be far superior to the Plus.

If anything I would expect the SE to actually run cooler than the Plus, because of more efficient electronics. The Mini by comparison is a much hotter CPU. In fact I would argue it generates more heat than the SE logic and analogue boards combined, plus you have an LCD power supply in there as well. I know my MacBook gets unbearably hot on my lap in only a few minutes, compared to my PowerBook 100 which never even felt warm after running for hours. WIth a stripped down SE the main issue is the trapped heat at the top and how quickly that heat can exhaust from the rather large rear vent. If the PSU & logic board are generating most of the heat, I would expect natural convection to allow most of that heat to exit the back, or at least heat generated from those components. The analogue board is essentially in the same configuration for both Macs, so the main issue remains: how quickly will hot air trapped at the top circulate and evacuate, and how fast will that continuous heat take to overcome the SE's natural convective abilities to keep the temperature within rated tolerances. I would love to get my hands on one of those clear SE's to do a smoke test and see the convective airflow ...

Nevertheless, I think we all agree with your conclusion: don't run an SE without a fan!

Some thoughts on your mini, though. If the fan runs often, I would be concerned about the operating environment, especially if the SE is trapping most of that hot air inside the case. Essentially you are operating the mini in an environment that may be outside the mini's rated specs, despite the fan working to cool it. It actually makes me wonder if you shouldn't be running a fan in your SE too!

 

[superpantoufle]

Some thoughts on your mini, though. If the fan runs often, I would be concerned about the operating environment, especially if the SE is trapping most of that hot air inside the case. Essentially you are operating the mini in an environment that may be outside the mini's rated specs, despite the fan working to cool it. It actually makes me wonder if you shouldn't be running a fan in your SE too!

You've got some good points. Actually, after posting this yesterday, I thought I had to re-think soe things about that setup. But maybe here isn't the best place to discuss it. My goal wasn't to go off-topic with wgoodf's question!

 

[joshc]

With wgoodf's questions answered, I think we can safely discuss superpantoufle's Macminitosh. I would actually disassemble the Mac mini and find a way to properly mount the logicboard, hard drive and optical drive inside the SE case in such a way that cooling will no longer be a problem. The Mac mini's case has very little ventilation to start with, and with all the components close together, it certainly doesn't aid airflow. If you did that, you might find cooling becomes less of a problem. You could also get a Molex extension to power an additional fan.

 

[superpantoufle]

Ok, then…

My goal was to keep things simple in the first place. It was just a side project, only for fun. So having the Mini untouched was a must, so I could easily get it off, using it elsewhere, or eventually resell it. At first I ran the Mini with its cover off, thinking it would help. It didn't, and the airflow was much better with the cover on

Now what I should certainly do, whenever I find some time to rework on that project, is put a silent fan on the rear panel's vents. Seems like the easiest step, still letting the Mini untouched. But keep in mind that I only rarely use that machine, mainly as an "Apple TV on steroids". But I never watch TV, anyway…